JCI: Effects of SARS-CoV-2 infection and vaccination on immune memory and boosting strategies

In order to contain the COVID-19 pandemic, high levels of immunity must be achieved globally
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However, it is unclear how long infection- or vaccine-induced immune memory will last

COVID-19 immune infection

With regard to natural infection, studies have shown that despite declining antibody levels, memory B and T cells are detectable within 8 months of recovery in most subjects, although 10-20% of them show weaker immune memory
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Information on the longevity of vaccine-induced immune memory is even more sparse, as immune activity began less than a year ago
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Real-world studies showed that protection against COVID-19 was significantly reduced in all age groups 6 months after a full mRNA vaccination cycle, although protection against severe illness and hospitalization remained high

The data raises the question of whether a dose increase is needed, with many countries now recommending a third dose six months after the second dose
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This paper investigated the immune memory and booster effects after SARS-CoV-2 infection and vaccination
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method:

method: method:

We performed a longitudinal evaluation of SARS-CoV-2 immune memory up to 8 months after mRNA vaccination in uninfected and COVID-19 recovered individuals
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We also assessed the immunological effects of booster injections in two cohorts of individuals

result:

result:

We found that memory cells were still detectable 8 months after vaccination, while antibody levels decreased significantly, especially in uninfected subjects
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Antibody levels decreased significantly, especially in uninfected subjects
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We also found that booster injections were effective in reactivating immune memory for the spike protein in uninfected subjects, but not in those with previous SARS-CoV-2 infection
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In infected subjects, booster injections were effective in reactivating immune memory for the spike protein, but not in those with previous SARS-CoV-2 infection
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Finally, we observed similar decay kinetics of humoral and cellular immunity to SARS-CoV-2 up to 1 year after natural infection in a cohort of unvaccinated individuals
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Figure 1: Anti-Spike Antibodies Decrease Faster After Vaccination in Naïve Individuals than in Subjects Recovering from COVID-19

Figure 3: Naïve individuals and subjects recovering from COVID-19 show similar proportions of Spike-specific B cells 8 months after vaccination

Figure 4: In naïve individuals and recovered COVID-19 patients, the frequency of specific CD4+ T cells was comparable at 1 month after vaccination and remained stable at 8 months after vaccination

Figure 6: Booster vaccination restores humoral and cellular immunity more effectively in naïve individuals than in recovered COVID-19 patients

Figure 7: Antibodies (but not B and CD4+ T cells) declined 1 year after natural infection

in conclusion:

Conclusion: Conclusion:

The short-term persistence of humoral immunity and reduced neutralization capacity against currently circulating SARS-CoV-2 variants may explain reinfection and breakthrough infection
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Long-lived memory B and CD4+ T cells may protect against severe disease development

Booster doses restore optimal immunity against the spike protein in uninfected subjects, while the need for booster doses in vaccinated COVID-19 recovered subjects has not been established

Original link: https://pubmed.

Original link: https://pubmed.

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