Covid booster needed for protection against Omicron variants, studies show

A COVID-19 booster dose will provide strong and broad antibody protection against Omicron sublineage variants of the SARS-CoV-2 virus, two new studies using serum from human blood samples suggest.

Researchers from the Ohio State University in the US tested neutralising antibody levels against the BA.2 and BA.3 Omicron variants and Deltacron, a recombinant variant created by the exchange of genetic material between Delta and Omicron.

The studies, published in the New England Journal of Medicine (NEJM), and Cell Host & Microbe journal, showed that a third mRNA vaccine dose was required to generate a high enough concentration of antibodies to neutralise BA.2 and Deltacron, as well as other Omicron variants, including the original BA.1, and BA.1.1.

Antibodies produced by just the two-dose series of mRNA vaccines were enough to neutralise BA.3 -- a sign this variant is not likely to produce a new surge of Omicron infections, the researchers said.

"Three doses is better for everything," said Shan-Lu Liu, the senior author of both studies and a virology professor at Ohio State University.

"People have been asking about the recombinant Deltacron and also BA.3, and now we have an answer. And it's good news," said Liu