Early Omicron infection unlikely to protect against current variant


People infected with the earliest version of the Omicron variant of the coronavirus, first identified in South Africa in November, may be vulnerable to reinfection with later versions of Omicron even if they have been vaccinated and boosted, new findings suggest.

Vaccinated patients with Omicron BA.1 breakthrough infections developed antibodies that could neutralise that virus plus the original SARS-CoV-2 virus, but the Omicron sublineages circulating now have mutations that allow them to evade those antibodies, researchers from China reported on Friday in Nature.

Omicron BA.2.12.1, which is presently causing most infections in the United States, and Omicron BA.5 and BA.4, which now account for more than 21% of new U.S. cases, contain mutations not present in the BA.1 and BA.2 versions of Omicron.

Those newer sublineages “notably evade the neutralising antibodies elicited by SARS-CoV-2 infection and vaccination,” the researchers found in test-tube experiments.

The monoclonal antibody drugs bebtelovimab from Eli Lilly and cilgavimab, a component of AstraZeneca’s Evusheld, can still effectively neutralize BA.2.12.1 and BA.4/BA.5, the experiments also showed.

But vaccine boosters based on the BA.1 virus, such as those in development by Pfizer/BioNTech and Moderna, “may not achieve broad-spectrum protection against new Omicron variants,” the researchers warned.

Adolfo Garcia-Sastre, a microbiology and infectious diseases researcher at the Icahn School of Medicine at Mount Sinai in New York City, suggested that better protection might be seen with vaccines that target multiple strains of the virus or with intranasal vaccines that would increase protection from infection and transmission by generating immunity in the lining of the nose, where the virus first enters.

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