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Popularization of research advances on COVID-19

Does vaccine efficacy depend on antibody levels?

In the fight against the COVID-19 pandemic it is important to have a varied arsenal of safe and effective vaccines. Since global demand is high, prices must remain low enough to ensure equitable worldwide distribution. To complicate matters, we do not have data on vaccine efficacy for certain sectors of the population (pregnant women, children, immunocompromised individuals or people with auto-immune diseases) and more transmissible variants regularly emerge. In vaccine research, correlates of protection (immunological markers that predict vaccine efficacy) are highly sought after. Antibodies have often played this role against several viral illnesses.

It was a multidisciplinary American team ((Moderna, Cambridge; Fred Hutchinson Research Centre, Seattle; the American Government; NIH, Bethesda; the American Consortium of Universities) which estimated the efficacy of the Moderna vaccine at 94% during phase 3 COVE tests, thereby enabling its distribution. At the same time, they tried to establish whether levels of blood antibodies could be used as correlates of protection. They assessed blood levels of anti-spike, anti-RBD and neutralizing antibodies, just after the 2nd injection and then 4 wee