Omicron subvariants BA.4 and BA.5 appear to escape antibody responses among both people who had previous Covid-19 infection and those who have been fully vaccinated and boosted, according to new data from researchers at Beth Israel Deaconess Medical Center, of Harvard Medical School.
However, Covid-19 vaccination is still expected to provide substantial protection against severe disease, and vaccine makers are working on updated shots that might elicit a stronger immune response against the variants.
Subvariants BA.4 and BA.5 have identical sequences of the spike protein.
The data shows that the BA.2.12.1, BA.4, and BA.5 subvariants substantially escape neutralizing antibodies induced by both vaccination and infection. Moreover, neutralizing antibody titers against the BA.4 or BA.5 subvariant and (to a lesser extent) against the BA.2.12.1 subvariant were lower than titers against the BA.1 and BA.2 subvariants, which suggests that the SARS-CoV-2 omicron variant has continued to evolve with increasing neutralization escape.
These findings provide immunologic context for the current surges caused by the BA.2.12.1, BA.4, and BA.5 subvariants in populations with high frequencies of vaccination and BA.1 or BA.2 infection, the study published in New England Journal of Medicine said on Wednesday.
According to CNN, the newly published findings echo separate research by scientists at Columbia University. They recently found that the BA.4 and BA.5 viruses were more likely to escape antibodies from the blood of fully vaccinated and boosted adults compared with other Omicron subvariants, raising the risk of vaccine-breakthrough Covid-19 infections.
"Our data suggest that Covid-19 still has the capacity to mutate further, resulting in increased transmissibility and increased antibody escape," Barouch wrote in the email. "As pandemic restrictions are lifted, it is important that we remain vigilant and keep studying new variants and subvariants as they emerge," Dr Dan Barouch, an author of the paper and director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center in Boston, reportedly told the CNN in an email interview.