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 vaccinated and boosted, new findings suggest .
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 in Nature†
Omicron BA.2.12.1, which currently causes the most infections in the United States, and Omicron BA.5 and BA.4, which now account for more than 21% of new US cases, contain mutations 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.
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.