Authors: Hachmann NP, Miller J, Collier AY, Ventura JD, Yu J

PMID: 35731894 PMCID: PMC9258748 DOI: 10.1056/NEJMc2206576


In recent months, multiple lineages of the omicron (B.1.1.529) variant of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) have emerged,1 with subvariants BA.1 and BA.2 showing substantial escape from neutralizing antibodies.2-5 Subvariant BA.2.12.1 is now the dominant strain in the United States, and BA.4 and BA.5 are dominant in South Africa (Figure 1A). Subvariants BA.4 and BA.5 have identical sequences of the spike protein.

We evaluated neutralizing antibody titers against the reference WA1/2020 isolate of SARS-CoV-2 along with omicron subvariants BA.1, BA.2, BA.2.12.1, and BA.4 or BA.5 in 27 participants who had been vaccinated and boosted with messenger RNA vaccine BNT162b2 (Pfizer–BioNTech) and in 27 participants who had been infected with the BA.1 or BA.2 subvariant a median of 29 days earlier (range, 2 to 113) (Tables S1 and S2 in the Supplementary Appendix, available with the full text of this letter at In the vaccine cohort, participants were excluded if they had a history of SARS-CoV-2 infection or a positive result on nucleocapsid serologic analysis or if they had received another vaccine against coronavirus disease 2019 (Covid-19) or an immunosuppressive medication.

Keywords: COVID-19, SARS-CoV2, omicron, subvariants

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