Neutralizing Immunity Induced Against the Omicron BA.1 and BA.2 Variants in Vaccine Breakthrough Infections. (22nd September 2022)

• Record Type: Journal Article
• Authors: Brazer, Noah; Morris, Mary Kate; Servellita, Venice; Anglin, Khamal; Saldhi, Prachi; Garcia-Knight, Miguel; Bethancourt, Sutana; Sotomayor-Gonzalez, Alicia; Wang, Baolin; Foresythe, Abiodun; Nguyen, Jenny; Gliwa, Amelia S; Pineda-Ramirez, Jesus; Sanchez, Ruth Diaz; Zhang, Yueyuan; Ott, Melanie; Wadford, Debra A; Andino, Raul; Kelly, J Daniel; Hanson, Carl; Chiu, Charles Y
• Is Part Of: Journal of infectious diseases. Volume 226:Number 10(2022)
• Page Start: 1688
• Page End: 1698
• Publication Date: 2022-09-22
• Subjects: Omicron BA.1 -- Omicron BA.2 -- and Delta SARS-CoV-2 variants -- COVID-19 -- breakthrough infection -- neutralizing antibodies -- vaccine boosting; Communicable diseases -- Periodicals; Diseases -- Causes and theories of causation -- Periodicals; Medicine -- Periodicals; Communicable Diseases -- Periodicals; Electronic journals; 616.9
• DOI: 10.1093/infdis/jiac384
• Languages: English
• ISSNs: 0022-1899

Abstract

Abstract: Background: As of early 2022, the Omicron variants are the predominant circulating lineages globally. Understanding neutralizing antibody responses against Omicron BA.1 and BA.2 after vaccine breakthrough infections will provide insights into BA.2 infectivity and susceptibility to subsequent reinfection. Methods: Live virus neutralization assays were used to study immunity against Delta and Omicron BA.1 and BA.2 variants in samples from 86 individuals, 24 unvaccinated (27.9%) and 62 vaccinated (72.1%), who were infected with Delta ( n = 42, 48.8%) or BA.1 ( n = 44, 51.2%). Among the 62 vaccinated individuals, 39 were unboosted (62.9%), whereas 23 were boosted (37.1%). Results: In unvaccinated infections, neutralizing antibodies (nAbs) against the three variants were weak or undetectable, except against Delta for Delta-infected individuals. Both Delta and BA.1 breakthrough infections resulted in strong nAb responses against ancestral wild-type and Delta lineages, but moderate nAb responses against BA.1 and BA.2, with similar titers between unboosted and boosted individuals. Antibody titers against BA.2 were generally higher than those against BA.1 in breakthrough infections. Conclusions: These results underscore the decreased immunogenicity of BA.1 compared to BA.2, insufficient neutralizing immunity against BA.2 in unvaccinated individuals, and moderate to strong neutralizing immunity induced against BA.2 in Delta and BA.1 breakthrough infections. Abstract : Neutralizing immunity was stronger against BA.2 than BA.1, regardless of infecting variant. Cross-variant neutralization was minimal in unvaccinated infections but moderate to strong in vaccine breakthrough infections. Observed differences in neutralizing immunity between unboosted and boosted breakthrough infections were comparable.