New Omicron strains better at dodging protection from vaccines and previous infection, study says

The US Food and Drug Administration told vaccine makers on June 30 that Covid boosters for this fall and winter should target the BA.4 and BA.5 Omicron strains.
PHOTO: Reuters

Omicron subvariants BA. 4 and BA. 5 pose a high infection risk for vaccinated people and those with mixed immunity from an Omicron infection and vaccination , according to a new study from Germany.

The study also found that only Bebtelovimab, a monoclonal antibody treatment developed by Eli Lilly, could efficiently block infection by all Omicron subvariants, while most other antibody treatments could not ward off the new strains.

The Omicron variant of the coronavirus, first identified in November, has since developed different sublineages.

The earliest subvariants, BA. 1 and BA. 2, were responsible for a wave of Covid-19 infections in early 2022, but they have been pushed out by other strains such as BA. 2.12.1, BA. 4, and BA.5.

Mutations on the spike proteins of these recent virus variants make them more efficient at dodging existing immunity. The BA.4 and BA.5 strains were responsible for a fresh wave of Covid-19 in South Africa in May and now a surge in cases in Britain.

In a study published in The Lancet Infectious Diseases on June 28, scientists analysed the plasma of 10 unvaccinated individuals infected with BA. 1 or BA. 2 in the spring of 2022. Their results suggest that previous BA. 1 or BA. 2 infections may offer little protection against subsequent BA. 4 or BA. 5 infections.

They then analysed the neutralising effect of vaccination-induced antibodies. Although three doses of the Pfizer-BioNTech vaccine induced antibodies capable of blocking all Omicron subvariants, the shots were less effective against BA. 2.12.1, BA. 4 and BA. 5 than against earlier subvariants.

A similar trend was observed for people who had been infected with BA. 1 or BA. 2 after being vaccinated with three doses of the Pfizer-BioNTech vaccine.

Researchers also studied 10 monoclonal antibody treatments for Covid-19 patients. They found that most had little to no effect against BA. 2.12.1, BA. 4, and BA.5. Only Bebtelovimab could effectively block infection by all Omicron subvariants, while S2H97 from Celltrion was only effective in high concentrations.

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The scientists concluded that BA. 4 and BA. 5 were “immune-evasion variants” that were more adept than previous Omicron strains at spreading in vaccinated people and those with previous infections.

“BA. 2.12.1 and particularly BA. 4 and BA. 5 are antibody evasion variants. Vaccination will still protect against severe disease induced by these variants but protection might be somewhat less efficient [than] that measured for previously circulating variants,” said the study’s senior author, Markus Hoffmann of the German Primate Centre-Leibniz Institute for Primate Research.

Scientists from Hannover Medical School and the University of Erlangen–Nuremberg also contributed to the research.

Globally, Omicron is the dominant coronavirus variant. As of last week, the BA. 2.12.1 strain was responsible for 11 per cent of infections, while BA. 4 accounted for 12 per cent and BA. 5 accounted for 43 per cent of cases, according to the World Health Organization.

“Our future studies must show whether BA. 2.12.1, BA. 4 and BA. 5 are not only less efficiently inhibited by antibodies but are also better at infecting lung cells,” said Stefan Poehlmann, also of the German Primate Centre, who headed the study along with Hoffmann.

“If this is the case, then an uptick in hospitalisations might be the consequence, although it should be stated that this has so far not been observed in South Africa, where BA. 4 and BA. 5 were first detected.”

The US Food and Drug Administration has asked Pfizer and Moderna to target the BA. 4 and BA. 5 subvariants as well as the original coronavirus strain when they update their Covid-19 boosters.

This article was first published in South China Morning Post.