By measuring antibodies against the SARS-CoV-2 spike protein in participants in an investigation phase 3 of the Moderna COVID-19 vaccination researchers discovered that the higher the level of antibody higher, the higher the level of vaccine’s protection against COVID-19.
The results aid in defining “correlates of protection” – or molecular biomarkers to measure how much immunity is required to fight infection. They also can help determine the appropriateness of COVID-19 mRNA vaccines as well as other COVID-19 vaccines. To reliably predict the level of vaccine effectiveness against diseases like COVID-19, the immuno marker correlates of immunity can be used.
As so, they are extensively sought-after in research on vaccines; the identification and validation of an indicator of protection could accelerate the clinical evaluation and regulatory approval process for existing vaccines, for new populations as well as for changes to the vaccine regimen and for the development of new vaccines. The protection offered by vaccines against many viral diseases has been proven to be associated with binding antibodies (bAbs) or neutralizing antibodies. There is evidence to suggest that antibodies are a predictor of protection against COVID-19, regardless of whether they are elicited through the virus or spike protein-based vaccines.
Following previous studies by other groups on non-human primates in which each of the antibody markers were associated with protection against SARS-CoV-2 replication following the vaccination of rhesus macaques, Peter Gilbert and colleagues determined whether the same SARS CoV-2 antibody markers were correlates of vaccine protection in a phase 3 trial of the mRNA-1273 COVID-19 vaccine.
By measuring the binding and neutralizing antibodies to the viral spike protein, they found that the higher the antibody level higher the level of protection provided by the mRNA vaccine. Based on any of the antibody markers, estimated COVID-19 risk was about 10 times lower for vaccine recipients with antibodies in the top 10% of values compared to those with negative/undetectable values. Antibody levels that indicate mRNA vaccine efficacy can therefore be used to inform vaccine regimen changes, the authors say.
Gilbert, P.B., and others. (2021) Immune Correlates Analysis of mRNA-1273 COVID-19 Vaccine Efficacy Trial. Science. doi.org/10.1126/science.abm3425.
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