Vaccine Info

Influenza Vaccines 2023

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Last reviewed
May 26, 2023

Flu Shots May 26, 2023 - What's New

Influenza vaccines, known as flu shots, protect people against viruses that research indicates will be the most common each year. However, every flu season is different, and each influenza virus can affect people differently, says the U.S. Centers for Disease Control and Prevention (CDC). Nevertheless, numerous studies show that influenza vaccination reduces the odds of intensive care unit admission and enables reduced hospital admissions. Most importantly, influenza vaccines do not cause seasonal flu since they are made with either killed or weakened viruses.

In addition, the World Health Organization (WHO) published its recommended composition of influenza virus trivalent and quadrivalent vaccines for use in the 2023-2024 southern hemisphere influenza season. And the WHO announced on April 26, 2023, its Preparedness and Resilience for Emerging Threats Initiative offering guidance on integrated planning for responding to respiratory pathogens such as influenza.

On May 23, 2023, the U.S. Food and Drug Administration (FDA) approved Xacduro, a new treatment for hospital-acquired bacterial pneumonia (HABP) and ventilator-associated bacterial pneumonia (VABP) caused by susceptible strains of bacteria called Acinetobacter baumannii-calcoaceticus complex, for adults 18 years of age and older.

Influenza Vaccines May 2023

Influenza vaccines are manufactured differently, and preparations have various indications as licensed by the FDA. All flu shots for the 2022-2023 season in the U.S. are quadrivalent, most will be thimerosal-free or thimerosal-reduced vaccine (93%), and about 20% will be egg-free. As of March 4, 2023, the CDC reported that about 173.37 million influenza vaccines had been distributed in the U.S. during the 2022-2023 flu season. 

On June 22, 2022, the CDC's ACIP reviewed the following presentations: Summary and Proposed Recommendations for the 2022-23 Influenza Season and Influenza Vaccines for Persons Aged ≥65 Years, by Lisa Grohskopf, MD, MPH. The ACIP based its recommendation on an evidence review suggesting higher dose flu vaccines (Fluzone High-Dose vaccine and Flublok recombinant vaccine) or adjuvanted flu vaccine (Fluad vaccine) are more effective than standard doses of unadjuvanted influenza vaccines for this age group. 

Insight Partners published the latest research report on May 22, 2023, estimating the global flu shot market CAGR of 7.4% from 2022 to 2028.

Flu Shot Effectiveness 2022-2023

Lisa Grohskopf, MD, MPH Influenza Division National Center for Immunization and Respiratory Diseases, presented to the U.S. FDA vaccine committee Preliminary 2022-23 Influenza Vaccine Effectiveness Estimates on March 7, 2023, which concluded, Influenza vaccination provided substantial protection against inpatient, emergency department, and outpatient illness among all ages. In addition, a CDC analysis published on February 22, 2023, and an MMWR on February 24, 2023, stated that 2022-2023 influenza vaccine preliminary effectiveness was about 71% protective of pediatric patients and 54% of adults against related hospitalization. And influenza vaccination Coverage rates (2021-22) are posted by the CDC.

In Canada, the 2022/23 influenza vaccine reduced the risk of medically attended illness by about 50%, higher than in Europe (29%) during the last flu season. And in September 2022, Australia reported preliminary estimates from sentinel hospitals that flu shot effectiveness appears at the lower end of the moderate vaccine effectiveness (40-60%) range.

The U.S. CDC ACIP meeting on October 20, 2022, reviewed the Comparison of Influenza Vaccine Effectiveness against outpatient and inpatient illness in the 2021–22 season; provided low to non-significant protection (36%) against predominant influenza A/H3N2 illness of varying severity slide #18. Previously, Lisa Grohskopf, with the CDC's Influenza Division, presented highlights regarding the current flu season during the ACIP meeting on June 22, 2022. Preliminary results for the 2021–22 flu season indicate influenza vaccination reduced acute respiratory illness due to influenza A(H3N2) virus by 35% (95% CI: 19‒47) based on data through April 30, 2022.

A recent study's finding reinforces the benefit of flu shots reducing illnesses even when circulating influenza viruses have drifted.

Quadrivalent Influenza Vaccines

Six months and older:

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

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

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

Fluzone Quadrivalent is an inactivated vaccine that prevents influenza disease caused by influenza A subtype viruses and type B viruses.

Two-49 years of age:

FluMist is an Intranasal, live quadrivalent vaccine containing four vaccine virus strains.

Flucelvax is a cell culture-based flu vaccine to help protect against four flu virus strains. 

Eighteen years and older:

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. In addition, Flublok contains three times the antigen of standard-dose inactivated influenza vaccines.

Sixty-five 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 four times the antigen of standard-dose inactivated influenza vaccines.

Influenza Vaccine China

AdimFlu-S (QIS) is a quadrivalent split inactivated vaccine containing hemagglutinin from four influenza virus strains (A and B). The China National Medical Products Administration approved Clover Biopharmaceuticals, Ltd.'s AdimFlu-S in January 2022 for individuals three years older.

COVID-Influenza Combination Vaccines

Novavax COVID-Influenza Combination vaccine candidate, anti-S IgG, and neutralization responses achieved levels seen in the Phase 3 trial with Novavax's prototype vaccine, with HAI responses generally consistent with Fluad® and Fluzone HD®.

Moderna's combination respiratory vaccine candidate (mRNA-1230) targets SARS-CoV-2, influenza, and RSV.

Pfizer and BioNTech announced the start of a Phase 1 trial to examine their combined influenza and COVID-19 candidate vaccine. This vaccine combines Pfizer's quadrivalent modRNA-based influenza vaccine candidate, qIR, and Pfizer and BioNTech's Omicron-adapted bivalent COVID-19 BNT162b2.

Dr. Katelyn Jetelina, MPH Ph.D., wrote on April 25, 2023, that there might be an increased risk of stroke if you get flu and COVID-19 vaccines simultaneously. The CDC ACIP reviewed this risk on April 19, 2023.

Influenza Vaccine Candidates

DelveInsight's influenza report indicates over 110 influenza vaccines are under development:

U.S. National Institute of Allergy and Infectious Diseases' universal influenza vaccine candidate H1ssF-3928 mRNA-LNP is conducting phase 1 research.

Pfizer's quadrivalent modRNA influenza vaccine candidate qIRV (22/23) encodes strains for the Northern Hemisphere 2022-23 cell culture- or recombinant-based influenza vaccines. It has launched a phase 3 clinical study with approximately 25,000 healthy U.S. adults.

CSL sa-mRNA bicistronic influenza vaccine candidates produced a potent, cross-reactive immune response against pandemic and seasonal influenza strains A(H5N1) and A(H1N1). In addition, the mRNA platform recently reported results from a significant Phase III vaccine study, meeting its primary and secondary endpoints of infection prevention and severe disease with a favorable safety and tolerability profile.

CureVac's seasonal influenza second-generation mRNA vaccine candidate, CVSQIV, was developed with GSK. The differentiated multivalent vaccine candidate features multiple non-chemically modified mRNA constructs to induce immune responses against relevant targets of four different influenza strains. An Extended Preliminary Phase 1 Data from Joint COVID-19 and Flu mRNA Vaccine Development Programs, and on May 8, 2023, the phase 1 study launched.

Flu-v Influenza Vaccine is a synthetic universal flu vaccine candidate that offers protection across a broad influenza spectrum forcing 1+NP forcing vaccine candidate consisting of MVA, a replication-deficient pox viral vector safely tested in thousands of patients, generate a robust immune reaction against Matrix 1 Nucleoprotein influenza antigens. 

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

Redeeflu (M2SR) is a nasal vaccine candidate utilizing a proprietary M2 deleted, single replication influenza virus.

NanoFlu is a quadrivalent recombinant hemagglutinin (H.A.) protein nanoparticle influenza vaccine produced by Novavax in its SF9 insect cell baculovirus system. NanoFlu uses H.A. amino acid protein sequences similar to the recommended wild-type circulating virus H.A. sequences. In addition, NanoFlu contains Novavax's patented saponin-based Matrix-M™ adjuvant.

CD388 (drug-Fc conjugate) is a highly potent, long-acting antiviral immunotherapy designed to deliver universal prevention and treatment of seasonal and pandemic influenza. Cidara Therapeutics intends to initiate a Phase 1 study in healthy volunteers in 2022.

Moderna's seasonal influenza vaccine candidates, mRNA-1020 and mRNA-1030, include eight mRNAs targeting hemagglutinin and neuraminidase at different doses and ratios.

Moderna's mRNA-1010 Quadrivalent Influenza Vaccine candidate encodes for the hemagglutinin protein from four seasonal influenza viruses.

Sinovac Biotech Ltd.'s two-dose inactivated quadrivalent influenza vaccine is conducting a phase 3 study with children in Chile.

Revelation Biosciences Inc. intranasal REVTx-99a is for the preventive treatment of H3N2 influenza (influenza A and B) infection in healthy humans, parainfluenza, rhinovirus, respiratory syncytial virus, and SARS-CoV-2 including its variants.

Cidara Therapeutics CD388 is a highly potent long-acting antiviral immunotherapy designed to deliver universal seasonal and pandemic influenza prevention, conducting a phase 1 study.

Osivax' OVX836 targets the nucleoprotein (NP), a highly conserved internal antigen. Unlike surface antigens, the NP is much less likely to mutate, alleviating the need for annual vaccination updates. The latest results from the Phase 2a dose-optimization study (OVX836-003) found that OVX836 maintained an excellent safety profile at all dose levels and provided protective efficacy in reducing PCR-confirmed influenza-like illnesses by 78%. Topline results from both studies are anticipated in the first half of 2023. 

The U.S. NIH's BPL-1357 is a whole-virus vaccine candidate comprising four non-infectious, chemically inactivated, low-pathogenicity avian flu viruses conducting a phase 1 study.

Emergex Universal Influenza Vaccine candidate is designed to induce CD8+ T cells specific to highly conserved parts of the influenza virus from both the positive and negative sense reading frames. 

Vaxess Technologies, Inc. MIMIX-Flu Vaccine Patch is conducting Phase I Clinical Trial, a first-in-man trial of VX-103.

Influenza Monoclonal Antibody Therapy

Vir Biotechnology, Inc.'s Phase 2 PENINSULA clinical trial evaluates the efficacy, safety, and tolerability of two different doses of VIR-2482 in preventing influenza illness. Designed to be a prophylactic against both seasonal and pandemic influenza A, VIR-2482 has been engineered to have an extended half-life, providing the potential for protection throughout an entire flu season. On December 21, 2022, Vir Bio announced the first participant was dosed in October 2022, and initial trial data are expected in mid-2023.

SAB Biotherapeutics SAB-176 is a fully-human polyclonal antibody candidate being studied for the treatment and post-exposure prophylaxis of pandemic and seasonal influenza in patients at high risk for severe influenza outcomes. On April 13, 2023, SAB announced that the FDA had granted Fast Track designation to SAB-176.

Influenza Vaccine Price

The U.S. CDC confirmed that the Vaccines For Children program is federally funded and provides vaccines and medicines at no cost to children. Internationally, UNICEF offers various vaccine price information. And InstantRx™ is a digital gateway empowering people to find flu shot prices easily. According to Fortune Business Insights, the Global Influenza Vaccine Market size is estimated to reach USD 13.58 Billion by 2029, exhibiting a CAGR of 8.8% between 2022 and 2029.

Flu Shots For Children

Flu vaccination coverage for children (six months to 17 years) as of late April 2022 was about 2% lower than last season (55.3% compared to 57.3%).

Flu Shots For Pregnant Women

Geeta Swamy, MD ACIP, presented on October 20, 2022 - A clinical Trial to compare the safety of Recombinant Influenza Vaccine versus Quadrivalent Inactivated Influenza Vaccine in Pregnancy (NCT03969641).

Flu Shots For Seniors

Sinead Morris, Ph.D., recently presented to the CDC's ACIP: Recommending that enhanced seasonal influenza vaccines in adults aged 65 and older could have wide-ranging impacts on the influenza burden. And Lisa Grohskopf, Influenza Division, CDC, presented: Influenza Vaccines for Older Adults: GRADE Summary. And the JAMA Network reported on August 9, 2022, that adults aged 65 years or older should receive high-dose or adjuvanted seasonal influenza vaccines.

Flu Shots and Alzheimer's Disease

The Journal of Alzheimer's Disease published a Research Article on June 13, 2022, by UTHealth Houston researchers - Risk of Alzheimer's Disease Following Influenza Vaccination: A Claims-Based Cohort Study Using Propensity Score Matching. People who received at least one influenza vaccine were 40% less likely than their non-vaccinated peers to develop Alzheimer's disease over four years. - The RR was 0.60 (95% CI, 0.59–0.61), and ARR was 0.034 (95% CI, 0.033–0.035), corresponding to a number needed to treat 29.4. Conclusion: This study demonstrates that influenza vaccination is associated with reduced AD risk in a nationwide sample of seniors.

Flu Shots and Asthma

The AAP journal Pediatrics published on March 28, 2022, Safety of Live Attenuated Influenza Vaccine in Children With Asthma. Conclusion: LAIV4 was not associated with an increased frequency of asthma exacerbations, an increase in asthma-related symptoms, or a decrease in peak expiratory flow rate compared with IIV4 among children aged 5 to 17 years with asthma. 

Flu Shots and Diabetes

Flu vaccination is essential for people with diabetes because they are at higher risk of developing severe flu complications, says the CDC. About 34% of adults hospitalized with the seasonal flu reported to the CDC had diabetes in recent seasons.

Flu Shots and Pneumonia

Pneumonia can often be prevented following vaccination. As of December 29, 2022, the CDC confirmed among the 2,117 deaths reported last week, 968 listed pneumonia as an underlying or contributing cause of death on the death certificate, 866 had COVID-19, and 283 listed influenza. While current mortality is due primarily to pneumonia and COVID-19, the proportion due to flu is increasing. 

In meta-analyses, influenza vaccination significantly reduces pneumonia- and influenza-related hospitalizations. And on May 31, 2022, a peer-reviewed Original Investigation published by The JAMA Network found that 'Patients with pneumonia admitted to hospitals with high all-cause readmission rates were more likely to develop adverse events during the index hospitalization.'

Flu Shots and Stroke Risk

The peer-review journal Neurology published a Research Article on September 7, 2022 - Influenza Vaccination and Risk of Ischemic Stroke: A Population-Based Case-Control Study. Seniors who received an influenza vaccine were about 12% less likely to have an ischemic stroke (adjusted OR 0.88, 95% CI 0.84-0.92). The study looked at ischemic strokes, caused by a blockage of blood flow to the brain and is the most common type of stroke.

Flu Shots and Heart Failure

The Lancet Global Health published a study: Influenza vaccine to reduce adverse vascular events in patients with heart failure: a multinational, randomized, double-blind, placebo-controlled trial - Major cardiovascular events are an essential contributor to influenza-associated morbidity and mortality - suggests that there is likely a clinical benefit of giving influenza vaccine, given the apparent reduction in pneumonia, a moderate reduction in hospitalizations, and a reduction in cardiovascular events and deaths during periods of peak circulation of influenza.

In this study published by the JAMA Network in April 2022, the receipt of influenza vaccination was associated with a 34% lower risk of major adverse cardiovascular events, and individuals with recent adverse cardiovascular events had a 45% lower risk.

Nasal Flu Shots United Kingdom

The U.K.'s NHS says the nasal spray vaccine offers the best protection for children aged 2 to 17 years. They'll be offered a flu vaccine injection if the nasal spray vaccine is unsuitable. Injected flu vaccines are also safe and effective. If it's their first time vaccinated against the flu, children under nine years old with long-term health conditions will usually be offered a 2nd dose of the flu vaccine four weeks after the 1st dose. 

Flu Shot Side Effects

Influenza vaccines can cause side effects, says the U.S. CDC. However, flu shot side effects are generally mild and dissipate within a few days.

Avian Influenza (Bird Flu) Vaccines 2023

The U.S. government has approved a vaccine for one type of avian influenza (bird flu) virus that protects people from infection and severe disease. However, the CDC says the annual flu shot offers unknown protection against avian influenza. Zoonotic Influenza (Bird Flu) outbreaks (humans, mammals, and avian) news for 2023 is posted at this link.

Influenza Season 2023

The U.S. CDC FluView week #20 report confirmed on May 26, 2023, seasonal flu rates were low nationally last week. However, 154 influenza-associated pediatric fatalities (about one-third were vaccinated) were reported during the 2022-2023 flu season. In addition, the WHO published Influenza Update N° 445 on May 15, 2023, stating influenza detections decreased after a peak in late 2022. And the European CDC reported on April 14, 2023, following a peak at week 51/2022, influenza activity had been decreasing across the Region until week 4/2023 before rising again to around 25% positivity between weeks 6 and 11/2023 and falling again to 15% positivity for week 14/2023. In the U.K., as of April 13, 2023, the Respiratory Datamart reported influenza positivity remained low and stable at 1.4% in week 14 compared with 1.6% in week 13.

Clinical Trials

No clinical trials found