By Carolyn Crist
Contagious Omicron subvariants of the coronavirus, such as BA.1, BA.2, BA.4, and BA.5, can evade antibodies from previous infections and vaccinations, although booster shots appear to provide sufficient protection to prevent severe illness, according to a new study published in Science .
The finding comes as the Biden administration considers expanding access to a second booster vaccine to all adults due to the spread of BA.4 and BA.5. People over 50 and immunocompromised individuals over 12 have been eligible for a second booster since March.
BA.5 is "probably the most important one in the study right now, as it's about to become globally dominant," John Bowen, co-senior author of the study and a biochemist at Washington University School of Medicine, told Fortune .
Bowen and his colleagues began investigating Omicron variants months ago, starting with the BA.1, BA.2, and BA.2.12.1 subvariants, which were dominant at the time. They then added BA.4 and BA.5, which are now dominant in the US and several other countries.
The research team evaluated the properties of the subvariants and assessed how a panel of seven COVID-19 vaccines could protect against Omicron strains, including injections manufactured by Pfizer, Moderna, Johnson & Johnson, AstraZeneca, Novavax, Sputnik V, and Sinopharm.
The researchers found that all 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 discovered that BA.5 can outperform 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 vaccination increased antibody protection against all Omicron subvariants to decent levels, regardless of the vaccine used.
“We were able to look at essentially all of the prominent vaccine platforms in the world side by side and see that, despite how scary this variant is, all of these vaccine platforms are going to elicit strong immune responses,” Bowen said.
At first, the booster shot data for BA.5 took him by surprise.
“When I was looking at the data after the third shot, I had to replay it over and over because I was like, ‘Why am I not seeing this as evasive immune as other people have said?’” Bowen told Fortune . “We were really excited to see that, even though it’s more evasive immune than the others we tested, the previous methods will still protect against it.”
The research, which received funding from the National Institute of Allergy and Infectious Diseases and the Department of Health and Human Services, was conducted by a team of nearly three dozen researchers in 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 by fall. Meanwhile, Bowen said, research indicates that current vaccines and boosters are still effective against severe disease.
“We fully agree that it is very important to continue trying to find better ways to manufacture protective vaccines. It will take some time to achieve this,” he said. “If people need vaccines, we know that current booster methods will be protective.”