BA.4, BA.5 sister variants escape antibody response more than previous strains

BA.4 and BA.5 can substantially escape neutralizing antibody responses from both vaccination and previous infection, according to research from a team at Beth Israel Deaconess Medical Center in Boston.

The CDC estimates that strains of COVID-19 — known as “sister variants” — now account for nearly 35 percent of U.S. cases.

Researchers evaluated antibody responses to numerous omicron subvariants in 27 people who had been vaccinated and boosted, as well as 27 people with a previous infection.

The findings, published June 22 in the New England Journal of Medicineshowed that antibody responses against BA.4 and BA.5 were twenty-fold lower than against the original omicron strain and three-fold lower against sub-variants BA.1 and BA.2.

“We observed a 3-fold reduction in neutralizing antibody titers induced by vaccination and infection against BA.4 and BA.5 compared to BA.1 and BA.2, which are already significantly lower than the original COVID-19 variants, Dan Barouch, MD, PhD, study author and director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center, told CNN

dr. Barouch added that the data indicate that the new strains will lead to increases among vaccinated populations, as well as populations with high levels of immunity to BA.1 and BA.2 from previous infections. “However, it is likely that vaccine immunity will still provide substantial protection against serious diseases with BA.4 and BA.5,” he said. CNN

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