Vaccine Info

Influenza Vaccines

Authored by
Staff
Last reviewed
April 10, 2021

Influenza vaccines, known as flu shots, protect people against the influenza viruses that research indicates will be most common during the upcoming season. Most importantly, influenza vaccines do not cause the seasonal flu since they are made with either killed or weakened viruses, says the U.S. CDC.

Seasonal flu vaccines fight infection by inducing antibodies that target the HA head. This region varies season to season, which is why flu vaccines must be updated each year, says the U.S. NIH.

The most common flu shot for the 2020-2021 influenza season in the Northern Hemisphere are quadrivalent vaccines that protect people against four viruses: influenza A (H1N1) virus, influenza A (H3N2) virus, and two influenza B viruses said the CDC on August 21, 2020.

Most people over 6-months of age are encouraged to get vaccinated every flu season since influenza infections can create severe consequences. The U.S. CDC’s Advisory Committee on Immunization Practices has made this recommendation since the 2010-11 influenza season.

Two influenza vaccine types are widely available: inactivated influenza vaccines (IIV) and live attenuated influenza vaccines (LAIV), says the WHO. Two new influenza vaccines have been licensed for use in people aged 65 years and older for the 2020-2021 flu season: a quadrivalent high-dose influenza vaccine and a quadrivalent adjuvanted influenza vaccine. Previously, high-dose and adjuvanted influenza vaccines were only available in trivalent formulations.

Quadrivalent Influenza Vaccines - 2020-2021

6 months and older:

Afluria is an inactivated quadrivalent influenza vaccine indicated for active immunization against influenza disease caused by influenza virus subtypes A and type B.

Fluarix is prepared from influenza viruses propagated in embryonated chicken eggs.

Flulaval is a quadrivalent, split-virion, inactivated influenza virus vaccine prepared from virus propagated in the allantoic cavity of embryonated hens’ eggs.

Fluzone Quadrivalent is an inactivated vaccine indicated for the prevention of influenza disease caused by influenza A subtype viruses and type B viruses

2-49 years of age:

FluMist is an Intranasal vaccine that is a live quadrivalent vaccine formulated to contain four vaccine virus strains.

Flucelvax is a cell culture-based flu vaccine to help offer protection against 4 flu virus strains 

18-64 years of age:

Flublok is made without the use of eggs. Therefore, it is not subject to the mutations that are sometimes introduced into the vaccine during egg adaptation that can cause the traditional vaccines to be ineffective.

65 years and older:

Fluad consists of an inactivated, quadrivalent influenza virus antigen produced in eggs and an oil-in-water emulsion adjuvant, MF59C.1.

Fluzone High-Dose contains 4 times the antigen of standard-dose inactivated influenza vaccines.

Trivalent Influenza Vaccine - 2020-2021

65 years and older:

Fluad consists of an inactivated, trivalent influenza virus antigen produced in eggs and an oil-in-water emulsion adjuvant, MF59C.1.

Influenza Vaccine Candidates

Existing flu vaccines contain weakened or inactivated influenza viruses with a mix of hemagglutinins (HAs), the proteins that stud their surfaces. These vaccines primarily aim to trigger antibody responses against HA’s top part or head. Genetic changes in flu viruses rarely alter most of the head. But a small amount of the head does reassort, or mutate, frequently, which allows new viral strains to dodge any immune memory and forces flu vaccine makers to prepare new formulations each year, with updated HAs, wrote Jon Cohen, a staff writer for Science.

Flu-v Influenza Vaccine is a synthetic universal flu vaccine candidate offering long-lasting protection across a broad influenza spectrum.

MVA-M1+NP vaccine candidate consists of MVA, a replication-deficient pox viral vector safely tested in thousands of patients, to generate a strong immune reaction against Matrix 1 (M1) Nucleoprotein (NP) influenza antigens. 

NasoVAX is a recombinant intranasal vaccine that is being developed for both seasonal and pandemic use.

Redeeflu is a nasal vaccine candidate utilizing a proprietary M2 deleted, single replication influenza virus.

Zoonotic Influenza News

Please visit the latest Avian and Swine Influenza News.

2021–2022 Influenza Season Vaccine Composition

The World Health Organization recommended the Northern Hemisphere 2021–2022 influenza vaccine composition. The US Food and Drug Administration’s Vaccines and Related Biological Products Advisory Committee subsequently made the influenza vaccine composition recommendation for the 2021-2022 flu season in the USA. The detailed information is published on this webpage

Influenza Vaccine News

April 9, 2021 - The U.S. CDC published Key Updates for Week #13, ending April 3, 2021, including 'nation-wide, 1.0% of patient visits reported were due to Influenza-like-Illness (ILI). This ILI percentage is below the national baseline of 2.6%, and the current hospitalization rate is one-eighth the rate at this time compared to the 2011-12 flu season. This is much lower than average for this point in the season and lower than rates for any season since routine data collection began in 2005.

April 2, 2021 - The U.S. CDC Key Updates for Week #12, ending March 27, 2021, conclude by stating, 'Seasonal influenza activity in the USA remains lower than usual for this time of year.' However, there has been (1)  influenza-associated pediatric death occurring during the 2020-2021 flu season reported to CDC.

March 30, 2021 - The European Medicines Agency issued recommendations for the influenza virus strains that vaccine manufacturers should include in vaccines to prevent seasonal influenza from autumn 2021.

March 29, 2021 - The WHO published Influenza update #390, which stated 'despite continued or even increased testing for influenza in some countries, global influenza activity remained at lower levels than expected for this time of the year. Worldwide, influenza B detections accounted for the majority of the very low numbers of detections reported.'

March 27, 2021 - A study conducted in France published in The Lancet concluded 'Among patients admitted to hospital with community-acquired pneumonia who met clinical stability criteria, discontinuing β-lactam treatment after 3 days was non-inferior to 8 days of treatment. These findings could allow a substantial reduction of antibiotic consumption.'

March 26, 2021 - The U.S. CDC reported today between October 1, 2020, and March 20, 2021, FluSurv-Net sites in 14 states reported 210 laboratory-confirmed influenza hospitalizations for an overall cumulative hospitalization rate of 0.7 per 100,000 population. This is much lower than average for this point in the season and lower than rates for any season since routine data collection began in 2005. Hospitalization rates stratified by age will be presented once case counts increase to a level that produces stable rates by age.

March 24, 2021 - Researchers at the University of Washington School of Medicine announced they had developed experimental flu shots that protect animals from a wide variety of seasonal and pandemic influenza strains. If proven safe and effective, these next-generation influenza vaccines may replace current seasonal options by protecting against many more strains that current vaccines do not adequately cover. A study appears in the March 24 edition of the journal Nature.

March 19, 2021 - The Australian Technical Advisory Group on Immunisation released advice for immunization providers in its Statement on the administration of seasonal influenza vaccines in 2021. This year both flu and COVID-19 vaccines will be available in Australia. It is important to plan vaccination timing to give the best protection against both of these potentially serious diseases.

March 19, 2021 - The U.S. CDC reported, 'Between October 1, 2020, and March 13, 2021, FluSurv-NET sites in 14 states reported 203 laboratory-confirmed influenza hospitalizations for an overall cumulative hospitalization rate of 0.7 per 100,000 population. This is much lower than average for this point in the season and lower than rates for any season since routine data collection began in 2005, including the low severity 2011-12 season. The current rate is about one-fourth the rate seen at this time during the 2011-12 season.'

March 18, 2021 -  A paper published in the Journal of General Internal Medicine, physician-researchers at Beth Israel Deaconess Medical Center assessed the relative impact of COVID-19 on patients hospitalized with the viral infection in March and April 2020 versus patients hospitalized with influenza during the last five flu seasons at the medical center. Overall, the team demonstrated that COVID-19 cases resulted in significantly more weekly hospitalizations, more use of mechanical ventilation, and higher mortality rates than influenza.

March 15, 2021 - The WHO published Influenza update - #389, based on data up to February 28, 2021. 'The current influenza surveillance data should be interpreted with caution as the ongoing COVID-19 pandemic has influenced to varying extents health-seeking behaviors, staffing/routines in sentinel sites, as well as testing priorities and capacities in Member States. Globally, despite continued or even increased testing for influenza in some countries, influenza activity remained at lower levels than expected for this time of the year.'

March 12, 2021 - The Weekly U.S. Influenza Surveillance Report for Week #9, published by the U.S. CDC: 'Seasonal influenza activity in the United States remains lower than usual for this time of year.'

March 12, 2021 - The ECDC reported the influenza epidemic in the European Region has usually reached its peak by this point in the year, but despite widespread and regular testing for influenza viruses reported influenza activity remains at a very low level, likely due to the impact of the various public health and social measures implemented to reduce transmission of SARS-CoV-2. Of 1,026 specimens tested for influenza viruses in week 09/2021, three were positive from patients presenting symptoms to sentinel primary healthcare sites. No hospitalized laboratory-confirmed influenza cases were reported in week 09/2021.

March 8, 2021 - Health Canada reported no evidence of community circulation of influenza this flu season despite continued testing above seasonal levels. Influenza activity has remained below the threshold required to declare the start of the 2020-21 influenza season. No laboratory-confirmed outbreaks of influenza have been reported to date this season.

March 8, 2021 - Certain patients have an increased risk of influenza infections and poor serologic response to standard influenza vaccination. A new study found tandem high-dose influenza vaccination leads to more robust and more durable seroprotection in high-risk patients.

March 5, 2021 - The U.S. CDC's Weekly U.S. Influenza Surveillance Report for week #8 says, 'Seasonal influenza activity in the United States remains lower than usual for this time of year.' Nationwide during week #8, 0.9% of patient visits reported were due to Influenza-like Illness (ILI). This percentage is below the national baseline of 2.6% and represents approximately a 10% decrease week-over-week.

March 4, 2021 - Seqirus announced that the U.S. Food and Drug Administration had approved FLUCELVAX® QUADRIVALENT, the company’s cell-based quadrivalent influenza vaccine, for an expanded age indication for people two years of age and older.

March 3, 2021 - RESEARCH ARTICLE INFLUENZA: Broad neutralization of H1 and H3 viruses by adjuvanted influenza HA stem vaccines in nonhuman primates. Antibodies elicited by these headless HA stabilized-stem vaccines neutralized diverse H1 and H3 influenza viruses. They shared a mode of recognition analogous to human bnAbs, suggesting that these vaccines have the potential to confer broadly protective immunity against diverse viruses responsible for seasonal and pandemic influenza infections in humans.

March 1, 2021 - The WHO reported despite continued or even increased testing for influenza in some countries, influenza activity remained at lower levels than expected for this time of the year. In the northern hemisphere's temperate zone, influenza activity remained below baseline, though sporadic detections of influenza A and B viruses continued to be reported in some countries.

March 1, 2021 - PLOS reported 'the global burden of influenza-associated lower respiratory tract infections and hospitalizations among adults: A systematic review and meta-analysis. In this meta-analysis, the researchers estimated influenza viruses are associated with over 5 million hospitalizations worldwide per year. Together, the available data demonstrate the importance of influenza viruses as a cause of severe disease and hospitalizations in younger and older adults worldwide.'

February 26, 2021 - The U.S. CDC reported Key Updates for Week 7, ending February 20, 2021. Seasonal influenza activity in the United States remains lower than usual for this time of year.

February 26, 2021 - The WHO issued recommended composition of influenza virus vaccines for use in the 2021 - 2022 northern hemisphere influenza season.

February 26, 2021 - The National IHR Focal Point for the Russian Federation recently notified the WHO of the detection of avian influenza A(H5N8) in seven human clinical specimens. These are the first reported detection of avian influenza A(H5N8) in humans. According to the latest notifications from the World Organization for Animal Health, Afghanistan became the latest country to report highly pathogenic H5N8 avian influenza in poultry.

February 24, 2021 - Russian authorities reported the detection of influenza A(H5N8) virus infection in seven poultry workers in an outbreak of highly pathogenic avian influenza (HPAI) A(H5N8) virus on a poultry farm in the south of Russia. All seven human cases were reported to be mild or asymptomatic. HPAI A(H5N8) viruses circulated in European bird populations since 2014, causing large outbreaks and affected several million birds and poultry.

February 22, 2021 - MAJOR ARTICLE: Impact of the Influenza Vaccine on COVID-19 Infection Rates and Severity. The odds of testing positive for COVID-19 were reduced in patients who received an influenza vaccine compared to those who did not by 24%.

February 19, 2021 - The U.S. CDC reported 'Nationwide during week #6, 1.1% of patient visits reported were due to Influenza-like Illness. This percentage is below the national baseline of 2.6%. Between October 2020 and February 13, 2021, FluSurv-Net sites in 14 states reported 173 laboratory-confirmed influenza hospitalizations for an overall cumulative hospitalization rate of 0.6 per 100,000 population. This is much lower than average for this point in the season and lower than rates for any season since routine data collection began in 2005. Furthermore, just (1) influenza-associated pediatric fatality occurring during the 2020-2021 season has been reported to CDC.

February 17, 2021 - Twice annually, the WHO organizes consultations with an advisory group of experts to analyze influenza virus surveillance data generated by the WHO Global Influenza Surveillance and Response System (GISRS) and issues recommendations on the composition of the influenza vaccines for the following influenza season. These recommendations are used by the national vaccine regulatory agencies and the pharmaceutical companies to develop, produce and license influenza vaccines.

February 15, 2021 - The WHO Influenza Update N° 387, based on data up to January 31, 2021, reported that despite continued or even increased testing for influenza in some countries, influenza activity remained at lower levels than expected this time of the year. In the northern hemisphere's temperate zone, influenza activity remained below baseline, though sporadic detections of influenza A and B viruses were reported in some countries. In the southern hemisphere's temperate zone, influenza activity was reported at an interseasonal level. Worldwide, influenza B detections accounted for most of the meager numbers of detections reported.

February 12, 2021 - The US Centers for Disease Control and Prevention reported during week #5, about 1.1% of patient visits reported were due to Influenza-like Illness (ILI). This percentage is well below the national baseline of 2.6%.

February 10, 2021 - According to a study published by the Canadian Medical Association Journal (CMAJ), during the first wave of the pandemic, admission to hospital for COVID-19 was associated with significantly greater mortality, ICU use, and hospital length of stay than influenza. This study found that the risk of death from COVID-19 was 3.5 times higher than from influenza.

February 9, 2021 - Study published by The Lancet: Prevention of influenza during mismatched seasons in older adults with an MF59-adjuvanted quadrivalent influenza vaccine: a randomized, controlled, multicentre, phase 3 efficacy study. Summary: The prespecified criterion for showing the efficacy of aQIV in older adults was not met during the influenza seasons with high amounts of vaccine strain mismatch. Vaccine efficacy was higher against influenza cases associated with higher fever, representing a more clinically significant disease.

February 9, 2021 - The findings of a systematic review and meta-analysis published by The JAMA Network suggest that given the similarity in immunogenicity between the reduced dose intradermal and full dose intramuscular influenza vaccine, the low-dose intradermal vaccine could be a reasonable alternative to standard-dose intramuscular vaccination. It will be important to determine if this dose-sparing finding holds across age groups and for newer vaccines, particularly when recent high-dose formulations have demonstrated improved immunogenicity in older adults in whom immune responses have historically struggled.

February 8, 2021 - GAVI article: How COVID-19 is altering cold and flu seasons. Pandemic restrictions and wider use of flu vaccines may have explained 2020’s record low cases of seasonal flu, but what will the picture look like in tropical countries with year-round flu?

February 5, 2021 - The U.S. CDC published Key Updates for Week 4, ending January 30, 2021. The CDC says 'seasonal influenza activity in the United States remains lower than usual for this time of year.' Nationwide during week 4, 1.1% of patient visits reported were due to ILI. This percentage is below the national baseline of 2.6%.

February 3, 2021 - BioCryst Pharmaceuticals, Inc. announced that the U.S. Food and Drug Administration (FDA) had approved a supplemental new drug application for RAPIVAB® (peramivir injection), expanding the patient population of RAPIVAB for the treatment of acute uncomplicated influenza to include patients six months and older who have been symptomatic for no more than two days. Before this FDA approval, RAPIVAB had been indicated for patients two years and older.

February 2, 2021 - Study: A replication-competent adenovirus-vectored influenza vaccine induces durable systemic and mucosal immunity. Intranasal influenza vaccine spurred strong immune response in the Phase 1 study and reported the U.S. NIH.

February 1, 2021 - The WHO reported despite continued or even increased testing for influenza in some countries, influenza activity remained at lower levels than expected for this time of the year. In the northern hemisphere's temperate zone, influenza activity remained below baseline, though sporadic detections of influenza A and B viruses were reported in some countries. In the southern hemisphere's temperate zone, influenza activity was reported at an inter-seasonal level.

January 29, 2021 - Key insights from Week #3 were published by the U.S. CDC. Nationwide during week 3, 1.3% of patient visits reported were due to Influenza-like Illness. This percentage is below the national baseline of 2.6%.

January 23, 2021 - Study: Clinical and Economic Outcomes Associated with Cell-Based Quadrivalent Influenza Vaccine vs. Standard-Dose Egg-Based Quadrivalent Influenza Vaccines during the 2018–19 Influenza Season in the United States. Among the overall cohort, QIVc had higher adjusted rVEs against hospitalizations/ER visits related to influenza, all-cause hospitalizations, and hospitalizations/ER visits associated with any respiratory event than QIVe-SD. The adjusted annualized all-cause total costs were higher for QIVe-SD compared to QIVc ((+$461); p < 0.05).

January 22, 2021 - The U.S. CDC reported for week #2 of the 2021 flu season, 1.4% of patient visits reported through ILINet were due to Influenza-like Illness (ILI). This percentage is below the national baseline of 2.6%. During week #2, compared with week #1, the ILI visits rate decreased for five regions (Regions 2, 3, 4, 6, 9) and remained stable (change of ≤ 0.1%) in the remaining five regions. And a total of 136 laboratory-confirmed influenza-associated hospitalizations occurring between October 1, 2020, and January 16, 2021. This is lower than average for this point in the season and comparable to the overall rate seen during the 2011-12 flu season.

January 19, 2021 - Researchers observed decreased effectiveness of influenza vaccine with increasing time since vaccination for prevention of influenza A(H3N2), influenza A(H1N1)pdm09, and influenza B (Yamagata)-associated hospitalizations among adults. The maximum vaccine effectiveness (VE) was observed shortly after vaccination, followed by an absolute decline in VE of about 8 to 9% per month post-vaccination.

January 18, 2021 - The WHO reported, 'Globally, despite continued or even increased testing for influenza in some countries, influenza activity remained at lower levels than expected for this time of the year. In the northern hemisphere's temperate zone, influenza activity remained below interseasonal levels, though sporadic detections of influenza A and B viruses were reported in some countries. And in the temperate zone of the southern hemisphere, influenza activity was reported at an interseasonal level. Furthermore, various hygiene and physical distancing measures implemented by the Member States to reduce SARS-CoV-2 virus transmission have likely played a role in reducing influenza virus transmission.'

January 15, 2021 - The U.S.CDC reported 'nationwide during week #1, (1.7%) of patient visits reported through ILINet were due to Influenza-like Illness. This percentage is below the national baseline of 2.6%. A total of 129 laboratory-confirmed influenza-associated hospitalizations between October 1, 2020, and January 9, 2021, were reported by FluSurv-NET sites. This number is lower than average for this point in the season and comparable to counts seen at this point during the 2011-12 season. One influenza-associated pediatric death occurring during the 2020-2021 season has been reported to CDC.

January 15, 2021 - The Massachusetts Department of Public Health is removing the vaccination requirement which applied to all children over the age of 6 months attending Massachusetts child care, pre-school, kindergarten, K-12, or college due to the “mild” flu season and the fledgling efforts to administer the COVID-19 vaccine.

January 14, 2021 - JAMA Network Original Investigation - Safety, Reactogenicity, and Health-Related Quality of Life After Trivalent Adjuvanted vs. Trivalent High-Dose Inactivated Influenza Vaccines in Older Adults. In a randomized clinical trial of 757 older adults (378 receiving aIIV3 and 379 receiving HD-IIV3), the proportion of participants with moderate-to-severe injection-site pain was not higher after aIIV3 than HD-IIV3. No vaccine-related serious adverse events occurred, and postvaccination health-related quality of life was similar between aIIV3 and IIV3-HD groups. These findings suggest that a safety standpoint, aIIV3 or HD-IIV3, is an acceptable option to prevent influenza in older adults.

January 12, 2021 - Over 80% of those aged 65 and over in England have received the flu vaccine so far this year, the highest uptake ever achieved, reported the NHS. Flu vaccine uptake rates are higher than last season for all other eligible groups. This includes an uptake rate of 51.5% in clinical at-risk groups (aged under 65 years), which is the highest achieved in the last seven seasons.

January 12, 2021 - JAMA Network article: Broad, Durable Antibody Response in Universal Flu Vaccine Trial.

January 9, 2021 - A study published in the International Journal of Infectious Diseases found early administration of Oseltamivir (Tamiflu) is associated with a reduction in 30-day readmissions and composite-outcome of 30-day readmissions and mortality in adult hospitalized influenza patients when compared to delayed/no-treatment.

January 8, 2021 - Nationwide in the USA, during week #53, the U.S. CDC reported 1.6% of patient visits reported through ILINet were due to ILI. This percentage is below the national baseline of 2.6%. A total of 118 laboratory-confirmed influenza-associated hospitalizations between October 1, 2020, and January 2, 2021, were reported by FluSurv-NET sites. This number is lower than average for this point in the season and comparable to counts seen at this point during the 2011-12 season.

December 7, 2020 - The journal Nature publishes an article: A chimeric hemagglutinin-based universal influenza virus vaccine approach induces broad and long-lasting immunity in a randomized, placebo-controlled phase I trial.

January 6, 2021 - ORIGINAL ARTICLE: The Flu Vaccination May Have a Protective Effect on the Course of COVID-19 in the Pediatric Population: When Does Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) Meet Influenza?

January 6, 2021 - 'There hasn’t been a single recorded influenza case this winter. The Israel Center for Disease Control (ICDC) announced, signaling to doctors that their worst fear for this season isn’t panning out. The ICDC said Israelis took flu shots at almost double the normal rate this year, but the number still left 80% of people unvaccinated,' reported the Times of Israel.

January 5, 2021 - Clinical Infectious Diseases reported the cell-derived inactivated quadrivalent (four-strain) influenza vaccine (ccIIV4) was 7.6% more effective than its egg-derived counterpart (eIIV4) during the 2018-19 US flu season. These results support ccIIV4 as a potentially more effective public health measure against influenza than an egg-based equivalent.

January 5, 2021 - Study: Implementation of state laws requiring hospitals to offer influenza vaccination to their employees was associated with a 2.5% reduction in monthly pneumonia and influenza mortality rate (−0.16 deaths per 100 000 persons [95% CI, −0.29 to −0.02]; P = 0.022) during the years when the vaccine was well matched to the circulating strains. The most significant effects occurred among elderly persons and during peak influenza months.

January 4, 2021 - The WHO published Influenza Update N° 384 based on data up to December 20, 2020, which says During the COVID-19 pandemic, WHO encourages countries to continue routine influenza surveillance, test samples from influenza surveillance sites for influenza and SARS-CoV-2 viruses where resources are available and report epidemiological and laboratory information promptly to established regional and global platforms. In the countries of North America, influenza activity indicators, including the percent of tests positive for influenza and influenza-like illness (ILI) activity, were at very low levels, despite testing at usual or increased levels. In the United States of America, the percentage of deaths attributed to pneumonia, influenza, or COVID-19 remained above the epidemic threshold for pneumonia and influenza mortality established from historical data.

January 4, 2021 - The U.S. CDC published the Weekly U.S. Influenza Surveillance Report. 'Seasonal influenza activity in the United States remains lower than usual for this time of year,' stated this CDC report. The number of positive specimens tested for influenza was (0.2%).

December 29, 2020 - The U.S. CDC's Frequently Asked Influenza Questions for the 2020-2021 Season were updated.

December 28, 2020 - The U.S. CDC's weekly influenza report as of December 19, 2020, found that only 1.5% of patient visits reported were due to Influenza-like Illness (ILI), which is below the national baseline of 2.6% for week #51. Flu activity is unusually low at this time but may increase in the coming months, said the CDC.

December 21, 2020 - The WHO reported despite continued or even increased testing for influenza in some countries, influenza activity remained at lower levels than expected for this time of the year. For example, in the Northern Hemisphere's temperate zone, influenza activity remained below interseasonal levels. However, sporadic detections of influenza A and B viruses were reported in some countries.

December 18, 2020 - The U.S. CDC's weekly report stated, 'Seasonal influenza activity in the USA remains lower than usual for this time of year. Nationwide during week #50, about 1.6% of patient visits reported through ILINet were due to Influenza-like Illness. This percentage is below the national baseline of 2.6%.

December 11, 2020 - The U.S. CDC reported 'nationwide during week #49, 1.6% of patient visits reported through ILINet were due to ILI. This percentage is below the national baseline of 2.6%. Based on NCHS mortality surveillance data available on December 10, 2020, 14.3% of the deaths occurring during the week ending December 5, 2020 (week 49) were due to pneumonia, influenza, and COVID-19 (PIC). This PIC percentage is above the epidemic threshold of 6.5% for week 49.'

December 9, 2020 - The World Health Organization's latest report discloses (4) zoonotic influenza cases that have already been publicly reported between October 24, 2020, and December 9, 2020.

December 7, 2020 - The WHO reported, 'Globally, despite continued or even increased testing for influenza in some countries, influenza activity remained at lower levels than expected for this time of the year. In the northern hemisphere's temperate zone, influenza activity remained below inter-seasonal levels, though sporadic detections of influenza A and B viruses were reported in some countries. And in the temperate zones of the southern hemisphere, influenza activity was reported at an inter-seasonal level.

December 7, 2020 - Study: A chimeric hemagglutinin-based universal influenza virus vaccine approach induces broad and long-lasting immunity in a randomized, placebo-controlled phase I trial. The results suggest that chimeric hemagglutinins can be developed as universal vaccines that protect broadly against influenza viruses.

December 7, 2020 - Seqirus announced data from a systematic review and meta-analysis confirming the benefit of an MF59®-adjuvanted trivalent seasonal influenza vaccine (aTIV) for adults 65 years and older. Results indicate that relative vaccine effectiveness favored aTIV over non-adjuvanted standard dose quadrivalent and trivalent influenza vaccines in averting influenza-related medical encounters. The MF59 adjuvant is designed to enhance the immune response by increasing the magnitude and persistence of antibody response and creating more diverse cross-reactive antibodies. This may be important when there is a mismatch between the virus strains included in the vaccine and the strains circulating in the community.

December 4, 2020 - Study published in the JAMA: 'In patients with high-risk cardiovascular disease, such as recent myocardial infarction or hospitalization for heart failure, the high-dose trivalent inactivated influenza vaccine, compared with standard-dose quadrivalent inactivated influenza vaccine, did not significantly reduce all-cause mortality or cardiopulmonary hospitalizations. Influenza vaccination remains strongly recommended in this population.'

November 30, 2020 - The U.S. CDC reported the number of specimens testing positive for influenza during week #47 was (0.2%). Nationwide during week 47, 1.6% of patient visits reported through ILINet were due to Influenza-like Illness. This percentage is below the national baseline of 2.6%. No influenza-associated pediatric deaths occurring during the 2020-2021 season have been reported.

November 23, 2020 - The WHO GISRS laboratories tested more than 1,086,381 specimens during that time period. A total of 100 samples were positive for influenza viruses, of which 63 (63%) were typed as influenza A and 37 (37%) as influenza B. Of the sub-typed influenza A viruses, 7 (11.3%) were influenza A(H1N1)pdm09, and 55 (88.7%) were influenza A(H3N2). Of the characterized B viruses, 1 (6.7%) belonged to the B-Yamagata lineage and 14 (93.3%) to the B-Victoria lineage.

November 20, 2020 - Key Updates for Week #46, ending November 14, 2020, published by the U.S. CDC. Nationwide during week #46, 1.5% of patient visits reported through ILINet were due to ILI. This percentage is below the national baseline of 2.6%.

November 9, 2020 - The WHO Report #380 indicated that 140 specimens were positive for influenza viruses, of which 80 (57.1%) were typed as influenza A and 60 (42.9%) as influenza B. Of the sub-typed influenza A viruses, 2 (5.4%) were influenza A(H1N1)pdm09, and 35 (94.6%) were influenza A(H3N2). Of the characterized B viruses, 1 (6.7%) belonged to the B-Yamagata lineage and 14 (93.3%) to the B-Victoria lineage.

November 6, 2020 - In the USA, during week #44, 1.3% of patient visits reported through the U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) were due to influenza-like illness (ILI). This percentage is below the national baseline of 2.6%, reported the U.S. CDC. Based on mortality surveillance data available on November 5, 2020, 8.1% of the deaths occurring during the week ending October 31, 2020, were due to pneumonia, influenza, and COVID-19 (PIC). This PIC percentage is above the epidemic threshold of 6.0% for week #44.

October 29, 2020 - Women had a 0·7–0·9% risk of influenza per month of pregnancy during the influenza season, and antenatal influenza was associated with an increased risk for some adverse pregnancy outcomes. These findings support antenatal influenza vaccination's added value to improve perinatal outcomes.

October 28, 2020 - Kaiser Permanente dentists near Portland, Oregon, will soon begin a pilot program where patients over the age of 12 can receive an annual flu shot during their dental appointment. Oregon dentists are authorized to administer vaccines based on House Bill 2220.

October 26, 2020 - National Influenza Centres and other national influenza laboratories from 69 countries, areas, or territories reported data to FluNet for the time period from 28 September 2020 to 11 October 2020.

October 26, 2020 - South Korean authorities have said they found no direct link between the deaths and the vaccines against flu, which kills at least 3,000 South Koreans each year. “Do trust the health authorities’ conclusion...reached after a review with experts,” President Moon Jae-in said. “There is a need to expand the influenza vaccination this year not only to prevent the flu but also to ward off concurrent infection and spread of flu and COVID-19."

October 21, 2020 - Seqirus announced evidence indicating that an MF59®-adjuvanted trivalent seasonal influenza vaccine was more effective than standard, non-adjuvanted quadrivalent influenza vaccines in reducing influenza-related medical encounters in adults 65 years and older with at least one underlying health condition.

October 21, 2020 - Vir Biotechnology announced the presentation of preclinical and Phase 1 data demonstrating the broad neutralizing ability, high-level effector function, extended half-life, and tolerability of the VIR-2482 vaccine candidate in the prevention of influenza A, which will be presented at IDWeek 2020.

October 16, 2020 - The U.S. CDC confirmed during week #41 that only 1.2% of patient visits in the USA reported through the U.S. Outpatient Influenza-like Illness Surveillance Network were due to influenza-like illness.

October 13, 2020 - Study published by The Lancet: Efficacy, immunogenicity, and safety of a plant-derived, quadrivalent, virus-like particle influenza vaccine in adults (18–64 years) and older adults (≥65 years): two multicentre, randomized phase 3 trials. These efficacy studies are the first large-scale studies of any plant-derived human vaccine. Together, they show that the plant-derived QVLP vaccine can provide substantial protection against respiratory illness and influenza-like illness caused by influenza viruses in adults. QVLP vaccine was well tolerated, and no significant safety signal arose in participants who received the QVLP vaccine across the two studies.

October 8, 2020 - A recent study identified that cardiovascular events' seasonality might be associated with seasonality in Influenza‐Like‐Illness, though VE did not modify this relationship.

October 8, 2020 - Walgreens survey: Nearly three-fourths of U.S. adults plan on getting a flu shot this season, but a survey suggests misconceptions could keep the other fourth from getting vaccinated.

October 7, 2020 - Universal flu shot study published in Cell: Defining and Manipulating B Cell Immunodominance Hierarchies to Elicit Broadly Neutralizing Antibody Responses against Influenza Virus.

October 6, 2020 - The Massachusetts Department of Public Health (DPH) announced it had revised the influenza vaccination requirements for staff at nursing homes, rest homes, assisted living residences, adult day health programs, and out-of-hospital dialysis units. The DPH order eliminates staff's option to opt-out of getting a flu vaccine, with exemptions only for medical or religious reasons.

October 5, 2020 - A study found the 2018–2019 influenza vaccine reduced pediatric influenza A-associated hospitalizations and ED visits by 40% to 60%, even though the circulation of a drifted A(H3N2) clade.

October 5, 2020 - The ECDC published a systematic review of flu vaccine effectiveness studies. The evidence base for the efficacy and effectiveness of more recent and enhanced influenza vaccines is limited. Based on reviewed evidence, it is probable that these vaccines provide greater protection than no vaccination.

October 2, 2020 - CDC data aggregated during Week #39 found just 1.0% of patient visits reported through the U.S. Outpatient Influenza-like Illness Surveillance Network were due to influenza-like illness, which is well below the national baseline of 2.4%.

October 2, 2020 - Based on death certificate data, the U.S. CDC reported the percentage of deaths attributed to pneumonia, influenza, or COVID-19 for week #39 is 6.4%. This is currently lower than the rate during week 38 (9.5%).

October 1, 2020 - The American Academy of PediatricsPolicy Statement: Recommendations for Prevention and Control of Influenza in Children, 2020–2021.

October 1, 2020 - National Survey: Attitudes about Influenza, Pneumococcal Disease, and COVID-19.

September 29, 2020 - Study: Relative effectiveness of high dose versus standard-dose influenza vaccines in older adult outpatients over four seasons, 2015–16 to 2018–19. Among adults ≥65 years of age, recipients of standard and high dose influenza vaccines differed significantly in their characteristics. After adjusting for these differences, the high-dose vaccine offered more protection against A/H3N2 and borderline significant protection against all influenza A requiring outpatient care during the 2015–2018 influenza seasons.

September 25, 2020 - The World Health Organization (WHO) influenza vaccine advisors announced the strains to include vaccines for the Southern Hemisphere's 2021 season. When compared with the current season's vaccines, the group's recommendation swaps out both the 2009 H1N1 strains and the H3N2 influenza strains for egg-based vaccines, switching from the A/South Australia/34/2019-like virus to an A/Hong Kong/2671/2019-like virus.

September 25, 2020 - US CDC Weekly U.S. Influenza Surveillance Report: 2019-2020 Influenza Season Week 38, ending September 19, 2020.

September 23, 2020 - China's first domestically made live attenuated nasal spray flu vaccine was used for the first time in Xi'an, Shaanxi province, reported China's National Medical Products Administration.

September 22, 2020 - Study: Vaccine effectiveness against laboratory-confirmed influenza in Europe – Results from the DRIVE network during season 2018/19. The population-based cohort study included 274,077 vaccinated and 494,337 unvaccinated person-years; two vaccine brands were reported. Brand-specific IVE was estimated for Fluenz Tetra (36% [95%CI 24–45]) for ages 2-6y, Vaxigrip Tetra (54% [43–62]) for ages 6 months to 6y, and Vaxigrip Tetra (30% [25–35]) for ages 65 + y.

September 21, 2020 - WHO SAGE Seasonal Influenza Vaccination Recommendations during the COVID-19 Pandemic.

September 18, 2020 - The CDC's 2019-2020 Influenza Season Week #37, with data ending on September 12, 2020. Following the widespread adoption of community mitigation measures to reduce transmission of SARS-CoV-2, the virus that causes COVID-19, the percentage of U.S. respiratory specimens submitted for influenza testing that tested positive decreased from >20% to 2.3% and has remained at historically low interseasonal levels (0.2% versus 1–2%). Data from Southern Hemisphere countries also indicate little influenza activity, said the CDC.

September 16, 2020 - The publication of real-world evidence (RWE) on the company's cell-based quadrivalent influenza vaccine (QIVc) in the peer-reviewed medical journal Vaccine. This study's results indicate that QIVc was more effective than the standard, egg-based quadrivalent vaccine in preventing influenza-related hospitalizations/ER visits, all-cause hospitalizations, and hospitalizations/ER visits related to serious respiratory events.

September 11, 2020 - Scott Hensley, Ph.D., an associate professor of microbiology at the Perelman School of Medicine in Pennsylvania, shows high levels of non-neutralizing antibodies in middle-aged adults have contributed to the continued persistence of H3N2 viruses in the human population.

September 11, 2020 - The U.S. CDC 2019-2020 Influenza Season Week #36, ending September 5, 2020.

September 8, 2020 - The American Academy of Pediatrics, in its policy statement, “Recommendations for Prevention and Control of Influenza in Children, 2020–2021,” offers the option of a flu shot or nasal spray flu vaccine this season.

September 2, 2020 - The Janssen Pharmaceutical Companies announced that it had made a strategic decision to discontinue the development of pimodivir, an investigational antiviral treatment for influenza A infection.

September 1, 2020 - A large cohort study published by the Annals of Internal Medicine found no association between maternal influenza A(H1N1)pdm09 vaccination during pregnancy and risk for autism spectrum disorder in the offspring.

August 31, 2020 - ​The WHO published update number 375, based on August 16, 2020.

August 31, 2020 - Researchers have developed an approach to assess whether a vaccine activates the kind of immune cells needed for long-lasting immunity against new influenza strains. These results indicate that humans' influenza virus vaccination can elicit a GC reaction to which B cell clones targeting novel epitopes are more likely to be recruited, thereby broadening the spectrum of vaccine-induced protective antibodies against this rapidly mutating pathogen.

August 31, 2020 - Flu Vaccine Linked to Reduced CV Mortality in Adults With Diabetes. Although both diabetes and influenza are associated with increased risk of AMI and stroke, few studies have explored the relationship between influenza vaccinations and cardiovascular outcomes in individuals with diabetes, the authors wrote.

August 28, 2020 - U.S. CDC published Week #34 influenza report.

August 25, 2020 - A Cross-sectional Study: Acute Cardiovascular Events Associated With Influenza in Hospitalized Adults. In this population-based study of adults hospitalized with influenza, almost 12% of patients had an acute cardiovascular event.

August 25, 2020 - PAHO's Regional Update, Influenza. Epidemiological Week #33.

August 21, 2020 - Study: Equine influenza is a significant respiratory disease of horses that is largely controlled by vaccination in some equine populations. Virus-neutralizing antibodies, the mainstay of the protective immune response, are problematic in assaying for equine influenza virus, as most strains do not replicate efficiently in cell culture. 

August 21, 2020 - Next Generation Influenza Vaccines: Looking into the Crystal Ball. 

August 20, 2020 - U.S. CDC report: Prevention and Control of Seasonal Influenza with Vaccines: Recommendations of the Advisory Committee on Immunization Practices — the United States, 2020–21 Influenza Season. This report focuses on recommendations for using vaccines to prevent and control seasonal influenza during the 2020–21 season in the United States. A summary of the advice and a link to the most recent Background Document containing additional information is available.

August 19, 2020 - Massachusetts State public health officials announced that influenza immunization would be required for all 6 months of age or more aged attending Massachusetts child care, pre-school, kindergarten, K-12, and colleges and universities during 2021.

August 18, 2020 - A city-wide flu shot intervention was associated with increased influenza vaccination coverage, decreased illness-specific school absences among students, and lower influenza transmission community-wide, suggesting that the intervention may have produced herd effects.

August 17, 2020 - The WHO reported the Southern Hemisphere's flu season runs from May through October each year, but the season hasn't started yet. Sporadic influenza outbreaks have been detected in the Caribbean, Central America, and tropical parts of South America and Africa. Of about 205,000 flu specimens tested in the last half of July, only 40 were positive for flu, and half were influenza A, and half were influenza B. Of the subtyped influenza A viruses, 75% were H3N2.

August 14, 2020 - A new study published in JAMA concluded saying 'Despite the rapid pace of progress in the areas of SARS-CoV-2 diagnostics, treatment, and vaccine development, the population remains vulnerable to concurrent influenza and COVID-19 epidemics.'

August 13, 2020 - The first shipment of FLUMIST® QUADRIVALENT doses in the USA for the Northern Hemisphere's 2020-2021 influenza season. In response to the SARS-CoV-2 pandemic, AstraZeneca has increased FluMist doses by over 25% more than previously planned, a majority of which are expected to be available by the end of September 2020.

August 12, 2020 - Study: Trends in Childhood Influenza Vaccination Coverage, United States, 2012-2019. Influenza vaccination coverage among children appears to have plateaued. Only about half of the children in the United States were vaccinated against influenza. Improvements in the measurement of influenza vaccination and development and review of strategies to increase childhood influenza vaccination coverage are needed.

August 10, 2020 - The Alzheimer’s Association indicates possible connections between influenza and pneumonia vaccinations to reduce or delay cognitive decline. Both studies were previewed at AAIC before peer-reviewed journal publication.

August 10, 2020 - Original Article: Herpesvirus of turkey-vectored avian influenza vaccine offers cross-protection against antigenically drifted H5Nx highly pathogenic avian influenza virus strains.

August 9, 2020 - During 2020, most reported laboratory-confirmed influenza cases in Australia were influenza A (87.3%).

August 9, 2020 - The University of California announced requirements for flu shots for students, faculty, and staff.

August 7, 2020 - The U.S. CDC reported a total of 187 influenza-associated pediatric fatalities during the 2019-2020 flu season had been reported to CDC.

August 7, 2020 - Study: Evaluating the Relative Vaccine Effectiveness of Adjuvanted Trivalent Influenza Vaccine Compared to High-Dose Trivalent and Other Egg-Based Influenza Vaccines among Older Adults in the US during the 2017–2018 Influenza Season. For influenza-related hospitalizations/ER visits, aTIV was associated with a significantly higher rVE than QIVe-SD and TIVe-SD and was comparable to TIV-HD. aTIV was also associated with a significantly higher rVE than TIVe-SD against hospitalizations/ER visits related to pneumonia and asthma/COPD/bronchial events. aTIV and TIV-HD were associated with comparable annualized all-cause and influenza-related costs. Adjusted analyses demonstrated a significant benefit of aTIV against influenza- and respiratory-related events compared to the other egg-based vaccines.

August 7, 2020 - Researchers at Kanazawa University report in Nano Letters a high-speed atomic force microscopy study on a biological event that occurs when a flu virus enters and infects its host cell. The real-time visualization of influenza A hemagglutinin has enhanced the understanding of HA's fusogenic transition and its interactions with host endosomes.

August 6, 2020 - A new study concludes that opening clinics dedicated specifically to treating influenza can limit the number of people infected and help flatten the curve' or reduce the peak prevalence rate. While the work focused on influenza, the findings are relevant for policymakers seeking ways to reduce the ongoing COVID-19 pandemic impacts.

August 3, 2020 - The WHO reported influenza activity was reported at lower levels than expected for this time of the year. For example, in the Southern Hemisphere's temperate zones, the influenza season has not commenced. In the Northern Hemisphere's temperate zone, influenza activity remained at interseasonal levels.

July 30, 2020 - Seqirus announced it has begun shipping its portfolio of seasonal influenza vaccines to customers in the U.S. for the 2020/21 influenza season. Seqirus is well-positioned to supply up to 60 million vaccine doses for the U.S. market.

July 28, 2020 - GSK announced it started shipping more than 50 million quadrivalent influenza vaccine doses to US healthcare providers and pharmacies for the 2020-21 flu season. This data indicates a 9% increase from the last flu season.

July 27, 2020 - At the virtual American Heart Association’s Basic Cardiovascular Sciences 2020 Scientific Session, recent research found adults age 50+ who did get a flu shot had better outcomes in the year following vaccination, with a 28% lower risk of heart attack, a 73% lower risk of death, and an 85% lower risk of cardiac arrest.

July 23, 2020 - A study published by the NEJM: Baloxavir Marboxil for Prophylaxis against Influenza in Household Contacts.

July 9, 2020 - An analysis published by the NEJM showed that children 2 to 5 years old with birthdays in September through December were more likely to receive influenza vaccination and less likely to have influenza than those with birthdays earlier in the year before a vaccine is available.

July 9, 2020 - A recent study found that among adults, obesity is associated with susceptibility to H1N1pdm infection and with symptoms associated with H1N1pdm infection, but not with exposure to H3N2 infection or associated symptoms.

July 9, 2020 - Factors that influence vaccination decision-making among pregnant women: A systematic review and meta-analysis. Consistent with the extensive body of evidence on this topic, and HCP recommendation for routine vaccinations (seasonal influenza and pertussis vaccination) was a decisive factor influencing maternal vaccine acceptance that is associated with ten-times greater odds of being vaccinated over those who did not receive an HCP recommendation (pertussis OR 10.33, 95% CI 5.49–19.43; seasonal influenza OR 12.02, 95% CI 6.80–21.44).

July 2, 2020 - the U.S. FDA issued an emergency use authorization for the 3rd diagnostic test to detect and differentiate the viruses that cause flu and COVID-19 in individuals suspected of COVID-19 disease. The FDA has previously issued authorizations to BioFire Diagnostics LLC and QIAGEN GmbH for their tests, which include many other respiratory organisms in addition to the viruses that cause flu and COVID-19.

February 21, 2020 -  According to the CDC Morbidity and Mortality Weekly Report, the current influenza vaccine has been 45% effective overall against 2019-2020 seasonal influenza A and B viruses.

November 25, 2019 - Study: Forecasting type-specific seasonal influenza after 26 weeks in the United States using influenza activities in other countries. This study forecasts the 2018–2019 seasonal influenza after 26 weeks in the U.S. using the 2018 seasonal influenza in Australia and Chile. The correlation between the seasonal influenza patterns in the U.S., Australia, and Chile could be used to forecast the following seasonal influenza pattern, which can help to determine influenza vaccine strategy approximately six months ahead in the U.S. Our prediction model allows us to estimate peak timing, peak intensity, and type-specific influenza activities for next season at 40th week.

Universal Influenza Vaccine Research

A key focus of influenza research programs is developing a universal flu vaccine that provides robust, long-lasting protection against multiple flu subtypes, rather than a select few. Such a vaccine would eliminate the need to update and administer the seasonal flu vaccine each year. It could protect against newly emerging flu strains, potentially including those that could cause a flu pandemic.

Influenza Medicines

Several medications, such as Tamiflu or Xofluza (Baloxavir Marboxil), can reduce the seasonal flu's severity and duration. Still, they're most effective in the first 48 hours after experiencing influenza symptoms. Access to these medicines requires a healthcare provider's prescription.

    Influenza FAQs

    Note: This page's content is aggregated from the US CDC, the WHO, pharmaceutical manufacturers, university studies, and the Precision Vaccinations news network. This content is reviewed by healthcare professionals, such as Dr. Robert Carlson.