Evolution is on omicron subvariants’ side

A new study finds that as the coronavirus continues to evolve, each new omicron subvariant is increasingly likely to lead to reinfection or breakthrough infection. However, researchers say current vaccines are still doing a good job of protecting people against severe illness.

Meanwhile, vaccine makers are working on new and improved boosters that will hopefully be a better match against omicron and its subvariants. Food and Drug Administration advisers are slated to meet on June 28 to discuss the new booster shots.

The new study, published in the New England Journal of Medicine, echoes prior studies, and the finding is consistent with what we're seeing in the real world. Working in a laboratory, researchers measured neutralizing antibody response against the original Wuhan variant, compared to the new omicron variant and many of its sub variants.

Antibody levels are one measure of immune response, and often used as a rough indication of a variant's ability cause reinfection or breakthrough infection. Other parts of your immune system, like T-cells, are harder to measure but are a much better indicator of how well protected you are against severe disease.

Researchers found neutralizing antibody levels were six-fold lower against the original omicron variant, fourteen-fold lower against BA.2.12.1, and twenty-fold lower against BA.4/BA.5.

The BA.2.12.1 sub variant is currently dominant in the U.S., but the BA.4/BA.5 sub variants have been growing proportionally and now account for more than a third of estimated cases.

"It's essentially an arms race," said Dr. Dan Barouch, author on the recent study and director of the Center for Virology and Vaccine Research at Beth Israel Deaconess Medical Center in Boston. "As the population becomes more immune, the virus becomes more and more immune evasive."

The good news, said Barouch, is current vaccines are still working to dramatically reduce the risk of severe disease. "That's the most important goal of vaccination."