NEW YORK — 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, suggest new findings.
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 sublines now circulating have mutations that allow them to evade those antibodies, researchers from China reported. Friday (June) 17) in nature.
Omicron BA.2.12.1, which currently causes the most infections in the US, and Omicron BA.5 and BA.4, which now account for more than 21 percent of new cases in the US, contain mutations that are not present in the BA.1 and BA.2 versions of Omicron.
Those newer sublines “particularly evade the neutralizing antibodies elicited by SARS-CoV-2 infection and vaccination,” the researchers found in test-tube experiments.
Eli Lilly’s monoclonal antibody drugs bebtelovimab 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 under development by Pfizer/BioNTech and Moderna, “may not provide broad-spectrum protection against new Omicron variants,” the researchers warned.
Previous research that has not yet undergone peer review has suggested that unvaccinated people infected with Omicron are unlikely to develop an immune response that will protect them against other variants of the coronavirus.
“My personal bias is that while there may be some benefit to having an Omicron-specific vaccine, I think it will be of marginal benefit over keeping up with the existing vaccines and boosters,” said Dr. Onyema Ogbuagu, an infectious diseases researcher at Yale School of Medicine in New Haven, Connecticut, who was not involved in the new study.
“Despite immune evasion, vaccines can still be expected to protect against serious disease,” Ogbuagu said. “If you’re ready for a booster, buy a booster. What we’ve learned clinically is that it’s paramount to stay up to date on vaccines” to prevent high levels of Covid-19 antibodies in the blood preserve.
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Adolfo Garcia-Sastre, a microbiology and infectious disease researcher at the Icahn School of Medicine at Mount Sinai in New York City, suggested that better protection might be seen with vaccines targeting multiple strains of virus or with intranasal vaccines that the protection against infection and transmission by generating immunity in the mucous membrane of the nose, where the virus first enters.
Garcia-Sastre, who was not involved in the study, said that by the time a variant-specific vaccine becomes available, a new variant may have taken over.