Early Omicron infection unlikely to protect against current Covid-19 variants, says study

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.

Omicron Virus
Early Omicron infection unlikely to protect against current variants, says study. Image Credit: IE online

According to a new study, people infected with the earliest version of the Omicron variant of the coronavirus may be vulnerable to reinfection with later versions of Omicron even if they have been vaccinated and given booster doses. The first case of Omicron variant was identified in South Africa in November.

On the other hand, a study in China suggests that vaccinated patients with Omicron BA.1 breakthrough infections developed antibodies that could neutralize that virus plus the original SARS-CoV-2 virus, but the Omicron sublineages circulating now have mutations that allow them to evade those antibodies.

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 neutralizing 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.

Whereas the previous report (that has not yet undergone peer review) suggests that unvaccinated people infected with Omicron are unlikely to develop immune responses that will protect them against other variants of the coronavirus.

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