BA.5 Evades Vaccine and Infection Immune Response

July 22, 2022 — Contagious Omicron subvariants of the coronavirus — such as BA.1, BA.2, BA.4 and BA.5 — can escape antibodies from previous infections and vaccines, though booster shots appear to provide enough protection to prevent severe disease, according to a new study published in Science.

The finding comes as the Biden administration considers whether to expand access to a second booster shot to all adults due to the spread of BA.4 and BA.5. Ages 50 and older and immunocompromised people over age 12 have been eligible for a second booster since March.

BA.5 is “probably the most important one now in the study, as it’s about to become globally dominant,” John Bowen, a co-lead study author and biochemist at the University of Washington School of Medicine, told Fortune.

Bowen and colleagues began researching the Omicron variants months ago, starting with the BA.1, BA.2 and BA.2.12.1 subvariants, which were dominant at the time. Then they added in BA.4 and BA.5, which are now dominant in the U.S. and several other countries.

The research team assessed the properties of the subvariants and evaluated how a panel of seven COVID-19 vaccines could protect against the Omicron strains, including shots made by Pfizer, Moderna, Johnson & Johnson, AstraZeneca, Novavax, Sputnik V and Sinopharm.

The researchers found that all of the Omicron subvariants have the ability to escape antibodies to some extent, with increasing levels of immune evasion as the strains mutated and evolved.

In particular, they found that BA.5 can outcompete other subvariants because its spike protein binds to the human receptor cell more than six times better than the original coronavirus strain found in 2019. They concluded that BA.5 is the most immune-evasive COVID-19 variant to date.

At the same time, a booster shot increased antibody protection against all Omicron subvariants to decent levels, regardless of which vaccine was used.

“We were able to look at essentially every single prominent vaccine platform in the world side by side and see that, despite the scariness of this variant, all of these vaccine platforms are going to elicit solid immune responses,” Bowen said.

At first, the booster shot data for BA.5 took him by surprise.

“When I was seeing the data after the third shot, I had to repeat it over and over again because I was just like, ‘Why am I not seeing that this is as immune evasive as other people have said?’” Bowen told Fortune. “We were very excited to see that even though it’s more immune evasive than the other ones we tested, previous methods are still going to protect against it.”

The research, which received funding from the National Institute of Allergy and Infectious Diseases and Department of Health and Human Services, was conducted by a team of nearly three dozen researchers across the U.S., Argentina, Italy, Pakistan and Switzerland.

The FDA has advised vaccine companies to update their booster shots to target the BA.4 and BA.5 subvariants for the fall. In the meantime, Bowen said, the research indicates that current vaccines and boosters still work against severe disease.

“We totally agree it’s very important to continue trying to find better ways to make protective vaccines. It’s going to take some time to get those,” he said. “If people need vaccines, we know that current boosting methods are going to be protective.”