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Omicron Subvariants BA.4 and BA.5 Escape Antibodies : May Fuel Higher Risk Of Re-Infection

June 23, 2022

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.

The levels of neutralizing antibodies that a previous infection or vaccinations elicit are several times lower against the BA.4 and BA.5 subvariants compared with the original coronavirus, according to the new research published in the New England Journal of Medicine on Wednesday.

 
Study shows a higher risk for reinfection
"We observed 3-fold reductions of neutralizing antibody titers induced by vaccination and infection against BA4 and BA5 compared with BA1 and BA2, which are already substantially lower than the original COVID-19 variants," 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, wrote in an email to CNN.

"Our data suggest that these new Omicron subvariants will likely be able to lead to surges of infections in populations with high levels of vaccine immunity as well as natural BA1 and BA2 immunity," Barouch wrote. "However, it is likely that vaccine immunity will still provide substantial protection against severe disease with BA4 and BA5."

 
The authors of a  separate study say their results point to a higher risk for reinfection, even in people who have some prior immunity against the virus. The US Centers for Disease Control and Prevention estimates 94.7% of the US population ages 16 and older have antibodies against the coronavirus that causes Covid-19 through vaccination, infection, or both.

BA.4 and BA.5 caused an estimated 35% of new Covid-19 infections in the United States last week, up from 29% the week before, according to data shared by the US Centers for Disease Control and Prevention on Tuesday.

BA.4 and BA.5 are the fastest spreading variants reported to date, and they are expected to dominate Covid-19 transmission in the United States, United Kingdom and the rest of Europe within the next few weeks, according to the European Centre for Disease Prevention and Control.



'COVID-19 still has the capacity to mutate further'
In the New England Journal of Medicine paper, among 27 research participants who had been vaccinated and boosted with the Pfizer/BioNTech coronavirus vaccine, the researchers found that two weeks after the booster dose, levels of neutralizing antibodies against Omicron subvariants were much lower than the response against the original coronavirus.

The neutralizing antibody levels were lower by a factor of 6.4 against BA.1; by a factor of 7 against BA.2; by a factor of 14.1 against BA.2.12.1 and by a factor of 21 against BA.4 or BA.5, the researchers described.

 
Efforts underway to update Covid-19 vaccines
Moderna's bivalent Covid-19 vaccine booster, named mRNA-1273.214, elicited "potent" immune responses against the Omicron subvariants BA.4 and BA.5, the company said Wednesday.

This bivalent booster vaccine candidate contains components of both Moderna's original Covid-19 vaccine and a vaccine that targets the Omicron variant. The company said it is working to complete regulatory submissions in the coming weeks requesting to update the composition of its booster vaccine to be mRNA-1273.214.

Moderna's data suggest that "the bivalent booster might confer greater protection against the BA.4 and BA.5 omicron strains than readministering the original vaccine to increase protection across the population.






















SOURCE: CNN
IMAGE SOURCE: PIXABAY