This text is taken from our newsletter “Le Courrier du coronavirus” of May 9, 2022. To subscribe, click here.
People vaccinated and nevertheless infected with the Omicron variant subsequently have much stronger immune protection against other variants than those who had not been vaccinated, according to a study published last Friday in the journal Nature.
The South Africa-based research team analyzed the immune response of samples taken from 15 vaccinated and 24 unvaccinated people who contracted the Omicron (BA.1) variant around the turn of the year 2022.
Three weeks after the onset of symptoms in the participants, the antibodies of the vaccinated people neutralized the Delta, Beta and BA.2 variants much more easily when faced with these viruses in the test tube. The news is particularly heartening regarding BA.2, which is now the dominant variant in the world.
Specifically, people infected with Omicron (BA.1) and vaccinated had 4.8 times more neutralizing antibodies against BA.2 than people infected and not vaccinated. In fact, unvaccinated people had only “weak” neutralization against variants other than BA.1 itself.
The researchers note that, in people who have had Omicron (BA.1), the gap in protection between vaccinated and unvaccinated people is “concerning”. “The implication is that infection with Omicron is not sufficient to provide protection, and that vaccination should be given even in areas where the prevalence of infection with Omicron is high in order to protect against the other variants,” they recommend.
Neutralizing antibodies are an important facet of the defense against COVID-19, but not the only one: cytotoxic T cells, natural killer cells and other types of antibodies also play important roles.
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