Evaluation of the efficacy of SARS-CoV-2 vaccination in elderly people over 80 years old

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K21115
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0908:Society medicine, nursing, and related fields
• Research Institution: Kobe University
• Principal Investigator: ISHIMARU HANAKO 神戸大学, 医学研究科, 助手 (20965892)
• Project Period (FY): 2022-08-31 – 2024-03-31
• Keywords: 新型コロナウイルス / ワクチン / COVID-19 / 中和抗体

Outline of Final Research Achievements

We investigated the effect of multiple doses of mRNA vaccine for the newly emerged variants on these populations, cross-neutralizing antibody titers were examined against SARS-CoV-2 variants, including BQ.1.1 and XBB. Blood samples were taken from residents at four long-term care facilities in Hyogo prefecture, Japan (median age, 91 years), after 3rd (n = 67) and 4th (n = 48) mRNA vaccinations, from April to October 2022. After 3rd vaccination, cross-neutralizing antibody prevalence against conventional (D614G) virus, Delta, BA.2, BA.5, BA.2.75, BQ.1.1, and XBB were 100%, 97%, 81%, 51%, 67%, 4%, and 21%, respectively. After 4th vaccination, the antibody positivity rates increased to 100%, 100%, 98%, 79%, 92%, 31%, and 52%, respectively. The 4th vaccination significantly increased cross-neutralizing antibody titers against all tested variants. The positivity rates for BQ.1.1 and XBB increased after 4th vaccination, although the titer value was lower than those of BA.5 and BA.2.75.

Free Research Field

ウイルス学

Academic Significance and Societal Importance of the Research Achievements

4回目のワクチン接種により、全変異株に対する交差中和抗体価が有意に上昇した。結論 BQ.1.1およびXBBの陽性率は，BA.5およびBA.2.75よりも低かったが，4回目のワクチン接種後に上昇した．ウイルスの急速な変異とワクチンの有効性を考慮すると，ウイルスの流行を考慮し，流行ごとに適したワクチンを開発できるシステムを構築する必要があることが示唆された。本研究は高齢者に対するワクチンの追加接種有効性を示す研究結果となり、今後のSARS-CoV-2感染症対策に貢献する研究成果を得たと考える。