Dödligt virus från Kina orsakar panik (SARS-CoV-2, COVID-19)

If I’ve already had COVID-19, do I need to get a vaccine?

We're learning that the length of protection is not as long as we had hoped. For instance, in Manaus, Brazil, where people got infected at a pretty high rate early on, we're already seeing pretty high rates of reinfection. How much of that is due to the new variant versus the immunity wearing off, we don't know.

I was hoping the protective immunity would last longer, but all we really can say for sure is about four or five months. It probably does protect longer, but the point is, if you've been infected before, you still want to get vaccinated. It’ll give you stronger, more durable and more long-lasting protection.

/.../In a study posted to the preprint server BioRxiv, researchers at Rockefeller University in New York City looked at how different types of immunity would protect against potential variants. (Studies posted to preprint servers have not been peer-reviewed.) To do so, they designed a modified version of the coronavirus spike protein with 20 naturally occurring mutations to test how antibodies would work against it.

These modified spike proteins were tested in lab dishes against antibodies from people who had recovered from Covid-19, from those who had been vaccinated and from those who had hybrid immunity. The spike proteins were able to evade the antibodies from the first two groups, but not antibodies from people with hybrid immunity.

Another study, from researchers at the Centers for Disease Control and Prevention, found among those who had been previously infected, vaccination reduced the risk of reinfection by more than twofold, compared to natural infection alone.

The number and variability of the neutralizing epitopes targeted by polyclonal antibodies in SARS-CoV-2 convalescent and vaccinated individuals are key determinants of neutralization breadth and, consequently, the genetic barrier to viral escape. Using chimeric viruses and antibody-selected viral mutants, we show that multiple neutralizing epitopes, within and outside the viral receptor binding domain (RBD), are variably targeted by polyclonal plasma antibodies and coincide with sequences that are enriched for diversity in natural SARS-CoV-2 populations. By combining plasma-selected spike substitutions, we generated synthetic ‘polymutant’ spike proteins that resisted polyclonal antibody neutralization to a similar degree as currently circulating variants of concern (VOC). Importantly, by aggregating VOC-associated and plasma-selected spike substitutions into a single polymutant spike protein, we show that 20 naturally occurring mutations in SARS-CoV-2 spike are sufficient to confer near-complete resistance to the polyclonal neutralizing antibodies generated by convalescents and mRNA vaccine recipients. Strikingly however, plasma from individuals who had been infected and subsequently received mRNA vaccination, neutralized this highly resistant SARS-CoV-2 polymutant, and also neutralized diverse sarbecoviruses. Thus, optimally elicited human polyclonal antibodies against SARS-CoV-2 should be resilient to substantial future SARS-CoV-2 variation and may confer protection against future sarbecovirus pandemics.