Previous omicron infection also protects against BA.4 and BA.5


The subvariants omicron BA.4 and BA.5 of Sars-CoV-2 are better at evading the human immune system than any of their predecessors. However, recent research shows that previous infection with another variant (such as alpha, beta, or delta) still offers some protection against reinfection with BA.4 or BA.5. Previous infection with Omikron protects even better against reinfection. This is the result of a study in which researchers examined all Covid-19 cases in Qatar that have occurred since the beginning of the BA.4 and BA.5 wave of infections.

The work, published on July 12, 2022 on the medRxiv preprint server and awaiting peer review, is part of broader research into “how different immunities are combined,” says study co-author Laith Abu-Raddad, an epidemiologist at Weill Cornell Medical College in Qatar. Everyone has a different immunity history, depending on when and with what they were vaccinated against Covid-19 and whether they contracted the disease during the pandemic. “Different histories give people different levels of immunity to infection,” says Abu-Raddad. Knowing how these different immune responses work together in a person will be “very important for the future of the pandemic”.

To find out to what extent previous infection protects against the two omicron subvariants, Abu-Raddad and colleagues analyzed Covid-19 cases recorded in Qatar between May 7, 2022 – when BA.4 and BA.5 first entered the country. and July 4, 2022. The team discovered that infection with a pre-omicron variant resulted in reinfection with BA.4 or BA.5 with an efficacy of 28.3 percent and symptomatic reinfection with either subvariant with an efficacy of 15.1 percent prevented. Prior infection with Omicron provided greater protection, protecting 79.7 percent of subjects from reinfection with BA.4 and BA.5 and 76.1 percent of participants from a symptomatic course.



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