Immunity

Authored by
Staff
Last reviewed
September 25, 2021

COVID-19 Immunity Research:  Natural & Vaccine Conferred

Most people infected with the SARS-CoV-2 betacoronavirus and its mutating variants develop an immune response within the first few weeks after infection. And COVID-19 vaccines deliver various degrees of immunity against the variants.

Immunity to disease results when antibodies are developed in a person's system to that particular disease, says the U.S. CDC. Immunity is defined as either active or passive.

Active immunity occurs when the immune system produces antibodies to the disease. Antibodies can be made in two ways: when an individual is exposed to the disease resulting in natural immunity, or when the individual is vaccinated, typically with a killed or weakened form of the disease, resulting in vaccine-induced immunity.

Passive immunity is through antibody-containing blood products such as immune globulin, which may be given when immediate protection from a specific disease is needed. The significant advantage to passive immunity: protection is immediate, whereas active immunity takes time (usually several weeks) to develop.

Natalie J. Thornburg, Ph.D., Lead respiratory virus immunology, U.S. CDC presented 'Adaptive immunity and SARS-CoV-2' to the Advisory Committee on Immunization Practices meeting on September 22, 2021. This presentation's conclusions are as follows:

1.) There are degrees of protection from different outcomes based on a person's level of immunity. Multiple components of the immune system are required to prevent infection and illness; these components are complex and dynamic. When a vaccinated person becomes infected, they may shed culturable virus, and therefore may be infectious.

2.) Antibodies decrease over time in all age groups; cellular memory is maintained after waning. Neutralizing antibodies likely confer a majority of, but not all, immunity. Cellular responses likely contribute to protection against severe disease through anamnestic response even after antibodies wane.

3.) Older adults – Start with lower neutralization titers than younger adults. Because they start at lower titers, they may be faster to fall below the lower limit of detection. May have less robust cellular memory generation because of immunosenescence and therefore may be more dependent on humoral immunity. Reduced neutralization of variant viruses may confound antibody waning in all age groups.

Children Innate Immunity

Childhood vaccine-mediated cross cellular immunity and immunomodulation might protect against the infections of COVID-19, reported a study published in 2020. And the immunological mechanisms that lead to a lower susceptibility or severity of pediatric patients are not entirely clear. For example, milder symptomatology could be attributed to innate immunity or previous coronavirus infections, while it is not yet fully understood how the differential expression of ACE2 in children could contribute to milder disease.

COVID-19 Herd Immunity

Another debated concept is 'Herd Immunity,' which is the indirect protection from a disease that occurs when a large percentage of a population is protected with antibodies to that particular disease. Herd immunity occurs when a large portion of a community (the herd) becomes immune to a disease, making the spread of disease from person to person unlikely, says the Mayo Clinic.

For example, various studies have shown that herd immunity against measles is about 95%, while the threshold for polio is about 80%, says the WHO

Unfortunately, the goal for SARS-Cov-2 herd immunity percentage is unknown at this time, says various researchers

COVID-19 Herd Immunity Reporting

As of September 16, 2021, the UK's Public Health England reported seroprevalence data indicates that approximately 97% of blood donors aged 17 and over have antibodies to SARS-CoV-2 from either infection or vaccination.

In addition, on September 2, 2021, The Lancet reported a U.S. CDC study based on over 1.4 million blood samples found about 83% of adult Americans already have SARS-CoV-2 immunity from either vaccination or prior infection. 

Hybrid Immunity

An article published by Science on June 25, 2021, concluded by stating, 'Combining two different kinds of vaccines in heterologous prime-boost regimen can elicit substantially stronger immune responses than either modality alone. Hybrid immunity to SARS-CoV-2 appears to be impressively potent. The synergy is primarily observed for the antibody response more than the T cell response after vaccination, although the enhanced antibody response depends on memory T cells. This discordance needs to be better understood.'

Immunity Testing

Antibody or serology tests detect antibodies in the serum (blood) within days to weeks following infection. An antibody test will show whether or not you have developed antibodies to COVID-19 after exposure or vaccination.

Antibody tests for COVID-19 are available through healthcare professionals and laboratories, such as Ulta Labs, that offer a COVID-19 semi-quantitative test for individuals who think they may have had COVID-19 and do not currently have symptoms. However, antibody tests cannot tell if you have an active SARS-CoV-2 virus infection. If you suspect you are infectious, contact your healthcare provider about getting a PCR test. 

According to the U.S. CDC, antibody testing is not currently recommended to determine if you are immune to COVID-19. Antibody testing should also not be used to decide if someone needs to be vaccinated, says the CDC.

SARS-CoV-2 Betacoronavirus Immunity News

September 17, 2021 - The journal Nature published an article that included 'research from immunologist Ali Ellebedy, at Washington University School of Medicine in St Louis, Missouri, helps to explain the vigor of the memory-B-cell response. His group took samples from the lymph nodes of vaccinated individuals and found tiny B-cell finishing schools — called germinal centers — that were churning out ever more potent immune cells as time went on. B cells in these structures randomly mutate their genes to create entirely new sets of antibodies. Those cells that produce the best antibody repertoires eventually win out through an evolutionary process that augments the immune system's ability to fight off Delta and other SARS-CoV-2 variants of concern. Ellebedy and his colleagues initially described the persistence of these germinal centers for 15 weeks post-immunization with an RNA-based jab — longer than anyone had ever seen before with older-technology vaccines for other ailments. Now, the researchers have unpublished data, following the germinal centers for up to six months. 

September 14, 2021 - The Annals of Internal Medicine published an Original Research - Population Immunity Against COVID-19 in the United States. The mean overall population immunity was 62%. Adults aged 65 years or older were estimated to have the highest immunity level at 77.2%. As of 15 July 2021, the U.S. population immunity against COVID-19 may still have been insufficient to contain the outbreaks and safely revert to prepandemic social behavior.

September 10, 2021 - Denmark recognizes natural immunity for students and the Corona Passport, in addition to COVID-19 vaccine-generated immunity.

September 7, 2021 - The journal Nature published an article discussing 'Innate immunity might be the key to why children have fared better with the virus. But the Delta variant poses new unknowns.' The novelty of SARS-CoV-2 leveled the playing field and showed that children are naturally better at controlling viral infections. But, unfortunately, almost all viruses have developed ways of evading the innate immune system, and COVID-19 is no exception to that rule," says Herold. "Right now — knock on wood — the kids are still winning with their innate immunity." 

September 2, 2021 - The JAMA Network published a U.S. CDC study that found 'a repeated cross-sectional study that included over 1 million blood specimens estimated SARS-CoV-2 seroprevalence weighted for differences between the study sample and general population increased from 3.5% in July 2020 to 20.2% for infection-induced antibodies and 83.3% for combined infection- and vaccine-induced antibodies in May 2021.

September 1, 2021 - The NEJM published a study based on data from the University of California San Diego Health (UCSDH) staff. From March to July 31, 2021, a total of 227 UCSDH health care workers tested positive for SARS-CoV-2 by RT-qPCR assay of nasal swabs; 130 of the 227 workers (57.3%) were fully vaccinated. Symptoms were present in 109 of the 130 fully vaccinated workers (83.8%) and 80 of the 90 unvaccinated workers (88.9%). The remaining seven workers were only partially vaccinated. No deaths were reported in either group. mRNA vaccine effectiveness exceeded 90% from March 2021 through June but fell to 65.5% (95% confidence interval, 48.9 to 76.9) in July 2021.

September 1, 2021 - The Journal of Immunology published a peer-reviewed study: Protracted yet Coordinated Differentiation of Long-Lived SARS-CoV-2-Specific CD8+ T Cells during Convalescence - results suggest that following a typical case of mild COVID-19, SARS-CoV-2–specific CD8+ T cells not only persist but continuously differentiate in a coordinated fashion well into convalescence into a state characteristic of long-lived, self-renewing memory.

August 31, 2021 - Local media reported a new study from Kerala, India, shows a single dose of Covishield following a Covid-19 infection gives "hybrid immunity" that is more potent than two vaccinations or infection alone. Those who develop hybrid immunity have such high levels of immunity, said lead investigator Dr. Padmanabha Shenoy.

August 31, 2021 - The journal JAMA Network published a study that stated: This study demonstrated a significantly higher humoral immunogenicity of the SARS-CoV-2 mRNA-1273 vaccine (Moderna) compared with the BNT162b2 vaccine (Pfizer-BioNTech) in infected as well as uninfected participants and across age categories. As such, the height of the humoral response after vaccination, which correlates with neutralizing antibody titers, might be clinically relevant.

August 30, 2021 - The NYT published an article: Does COVID-19 Vaccine Immunity Diminish?

August 29, 2021 - A non-peer-reviewed study found among 4,732 sampled cases, fully vaccinated persons admitted with COVID-19 were older (73 years), more likely to have three or more underlying medical conditions, and were residents of long-term care facilities.

August 26, 2021 - The Lancet published a study conducted in Thailand that concluded the percentages of individuals vaccinated with the inactivated whole-virus CoronaVac vaccine (Sinovac Biotech) with detectable NAbs against current variants of concern were lower in CoronaVac recipients than in the naturally infected cohorts.

August 25, 2021 - Comparing SARS-CoV-2 natural immunity to vaccine-induced immunity: reinfections versus breakthrough infections. This non-peer-reviewed Israeli study demonstrated that natural immunity confers longer-lasting and more robust protection against infection, symptomatic disease, and hospitalization caused by the Delta variant of SARS-CoV-2, compared to the BNT162b2 two-dose vaccine-induced immunity. In addition, individuals who were both previously infected with SARS-CoV-2 and given a single dose of the vaccine gained additional protection against the Delta variant.

August 24, 2021 - A non-peer-reviewed study: Impact of Delta on the viral burden and vaccine effectiveness against new SARS-CoV-2 infections in the UK. Abstract summary - With Delta, infections following two vaccinations had a similar peak viral burden to unvaccinated individuals. SARS-CoV-2 vaccination still reduces new infections, but the effectiveness and attenuation of peak viral burden are reduced with Delta.

August 19, 2021 - Large-scale study of antibody titer decay following BNT162b2 mRNA vaccine or SARS-CoV-2 infection. This non-peer-reviewed Israeli study demonstrates individuals who received the Pfizer-BioNTech mRNA vaccine have different kinetics of antibody levels compared to patients who had been infected with the SARS-CoV-2 virus, with higher initial levels but a much faster exponential decrease in the first group.

July 29, 2021 - Antibody Evolution after SARS-CoV-2 mRNA Vaccination. This non-peer-reviewed study conducted by Rockefeller University concluded that "memory antibodies selected over time by the natural infection have greater potency and breadth than antibodies elicited by vaccination. These results suggest that boosting vaccinated individuals with currently available mRNA vaccines would produce a quantitative increase in plasma neutralizing activity but not the qualitative advantage against variants obtained by vaccinating convalescent individuals."

July 20, 2021 - Longitudinal analysis shows durable and broad immune memory after SARS-CoV-2 infection with persisting antibody responses and memory B and T cells. After receiving institutional review board approvals, two longitudinal COVID-19 cohort studies at Fred Hutchinson Cancer Research Center (Seattle, Washington) and Emory University (Atlanta, Georgia) began.

July 14, 2021 - Single-cell profiling of T and B cell repertoires following SARS-CoV-2 mRNA vaccine. This non-peer-reviewed study was approved by the University of California Irvine Institutional Review Boards. "The establishment of immunity against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has become a central focus of current research efforts. Natural immunity following infection and vaccine-generated immunity provide two different pathways to immunity against the disease. mRNA vaccines have demonstrated significant protection against severe COVID-19 disease."

June 24, 2021 - Naturally enhanced neutralizing breadth against SARS-CoV-2 one year after infection. This study's data published in Nature suggest that immunity in convalescent individuals will be very long-lasting and that convalescent individuals who receive available mRNA vaccines will produce antibodies and memory B cells that should be protected against circulating SARS-CoV-2 variants.

June 19, 2021 - Necessity of COVID-19 vaccination in previously infected individuals. The Cleveland Clinic Health System based in Ohio evaluated the necessity of COVID-19 Vaccines for persons previously infected with SARS-CoV-2. In summary, the cumulative incidence of COVID-19 was examined among 52,238 employees in an American healthcare system. COVID-19 did not occur in anyone over the five months of the study among 2,579 individuals previously infected with COVID-19, including 1,359 who did not take the vaccine. This is a non-peer-reviewed study approved by the Cleveland Clinic Institutional Review Board.

May 24, 2021 - SARS-CoV-2 infection induces long-lived bone marrow plasma cells in humans. This study was lead by Washington University in St. Louis, MO, and published in Nature. "Seventy-seven participants who had recovered from SARS-CoV-2 infection and eleven control individuals without a history of SARS-CoV-2 infection were enrolled. Overall, our results indicate that mild infection with SARS-CoV-2 induces robust antigen-specific, long-lived humoral immune memory in humans."

May 12, 2021 - mRNA vaccine-induced T cells respond identically to SARS-CoV-2 variants of concern but differ in longevity and homing properties depending on prior infection status. "The results from this non-peer-reviewed longitudinal study provide reassurance that vaccine-elicited T cells respond robustly to emerging viral variants, confirm that convalescents may not need a second vaccine dose, and suggest that vaccinated convalescents may have more persistent nasopharynx-homing SARS-CoV-2-specific T cells compared to their infection-naïve counterparts."

May 3, 2021 - Discrete Immune Response Signature to SARS-CoV-2 mRNA Vaccination Versus Infection. "Our study, together with others, underscores the fine balance between antiviral immune responses that achieve clearance of the infection and durable protective immunity and those that lead to inflammation and immunopathology. A better understanding of the immunological features associated with protective immunity, immunopathology, and durability of protective immunological memory will aid not only in better treatments for viral diseases but also facilitate the rapid development of effective vaccines for new and re-emerging viral diseases that threaten public health."

November 5, 2020 - Study published by the journal Virology: T Cell Responses to Coronavirus Infection are Complicated.

October 2, 2020 - A new study led by scientists at La Jolla Institute for Immunology shows that memory helper T cells that recognize common cold coronaviruses also recognize matching sites on SARS-CoV-2, the virus that causes COVID-19.

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