Neutralization of Omicron subvariants BA.1 and BA.5 by a booster dose of COVID-19 mRNA vaccine in a Japanese nursing home cohort

• DOI: 10.1016/j.vaccine.2023.02.068
• Publication Date: 2023-02-27T05:28:15Z
• Authors: Masae Itamochi; Shunsuke Yazawa; Noriko Inasaki; Yumiko Saga; Emiko Yamazaki; Takahisa Shimada; Kosuke Tamura; Emi Maenishi; Junko Isobe; Masahiko Nakamura; Misuzu Takaoka; Hitoshi Sasajima; Chikako Kawashiri; Hideki Tani; Kazunori Oishi
• Keywords: Booster dose

The sustained epidemic of Omicron subvariants severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a worldwide concern, and older adults are at high risk. We conducted prospective cohort study to assess the immunogenicity COVID-19 mRNA vaccines (BNT162b2 or mRNA-1273) in nursing home residents staff between May 2021 December 2022. A total 335 SARS-CoV-2 naïve individuals, including 141 (median age: 88 years) 194 44 participated. Receptor-binding domain (RBD) nucleocapsid (N) protein IgG neutralizing titer (NT) against Wuhan strain, Alpha Delta variants, BA.1 BA.5 were measured serum samples drawn from participants after second third doses vaccine using pseudotyped virus. Breakthrough infection (BTI) was confirmed by notification positive anti-N result vaccination. Fifty-one experienced BTI during period. RBD NTs markedly increased SARS CoV-2 months dose vaccine, compared those 5 dose, declined dose. decline NT particularly marked aged ≥ 80 years. BTIs period, which occurred induced robust even five booster Further studies required sustainability elicited Omicron-containing bivalent adults.