Several vaccines against COVID-19 have proven safe and effective in clinical trials. It can be challenging to measure the protection a vaccine provides based on immunological markers. Such a predictor, a “correlate of protection”, could be useful in the development and approval of further vaccines and in the fight against emerging virus variants.
Peter B. Gilbert, Fred Hutchinson Cancer Research Center and University of Washington, Seattle, WA, USA, and colleagues have assessed the levels of neutralizing and binding SARS-CoV-2 antibodies in participants in the phase 3 trial of the Moderna COVID-19 vaccine (mRNA-1273, Spikevax) and determined their correlation with vaccine protection against COVID-19. These markers were measured after the second vaccination and four weeks later. The team confirmed that the higher the antibody level, the greater the protection afforded by the vaccine.
All markers were inversely associated with COVID-19 risk. For any of the studied markers, the estimated COVID-19 risk of the participants was about ten times lower for vaccine recipients with antibodies in the top 10 % of values than in those with a negative or undetectable antibody response. Antibody levels that predict mRNA vaccine efficacy could, thus, be used, e.g., to guide modifications of vaccine regimens when it comes to doses and schedules.
- Immune correlates analysis of the mRNA-1273 COVID-19 vaccine efficacy clinical trial,
Peter B. Gilbert et al.,
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