Unvaccinated Omicron Patients at Risk From Variants

(Reuters) – Infection with the Omicron variant of the coronavirus can significantly improve the immune system’s ability to protect against other variants, but only in people who have been vaccinated, South African researchers have found.

In unvaccinated people, an Omicron infection provides only “limited” protection against reinfection, they reported on Friday in Nature.

In 39 patients who had Omicron infections – including 15 who had been immunized with vaccines from Pfizer/BioNTech or Johnson & Johnson – the researchers measured the ability of immune cells to neutralize not only Omicron but also earlier variants.

At an average of 23 days after Omicron symptoms started, unvaccinated patients had 2.2-fold lower neutralization of the first version of the Omicron variant compared to vaccinated people, 4.8-fold lower neutralization of the second Omicron sublineage, 12-fold lower Delta neutralization, 9.6-fold lower Beta variant neutralization, and 17.9-fold lower neutralization of the original SARS-CoV-2 strain.

The gap in immunity between unvaccinated and vaccinated individuals “is concerning,” the researchers said.

“Especially as immunity wanes, unvaccinated individuals post-Omicron infection are likely to have poor cross-protection against existing and possibly emerging SARS-CoV-2 variants,” they said. “The implication may be that Omicron infection alone is not sufficient for protection and vaccination should be administered even in areas with high prevalence of Omicron infection to protect against other variants.”

SOURCE: https://go.nature.com/3w6YukR Nature, online May 6, 2022.

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