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Last reviewed
December 5, 2021

Immunity Research:  SARS-CoV-2 Infection & COVID-19 Vaccine

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 virus variants.

Immunity to disease results when antibodies are developed in a person's system to that particular disease, says the U.S. CDC. Immunity can be 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. The CDC stated data are presently insufficient to determine an antibody titer threshold that indicates when an individual is protected from infection. The immunity provided by vaccine and prior infection are both high, but not complete 

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.

Super COVID-19 Immunity

People who have previously recovered from COVID-19 have a more robust immune response after being vaccinated than those who have never been infected. Scientists are trying to find out why, wrote an article published by the journal Nature on October 14, 2021. A series of studies that compared antibody responses of infected and vaccinated people led to the establishment of memory B cells that make antibodies that have evolved to become more potent. Still, the researchers suggest this occurs to a greater extent after 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 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. 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.

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.


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.