Identification of neutralizing activity levels to prevent COVID-19 progression and expansion of vaccination programs

2023 Fiscal Year Final Research Report

• Project/Area Number: 22K20768
• Research Category: Grant-in-Aid for Research Activity Start-up
• Allocation Type: Multi-year Fund
• Review Section: 0803:Pathology, infection/immunology, and related fields
• Research Institution: University of Toyama
• Principal Investigator: Kawasuji Hitoshi 富山大学, 学術研究部医学系, 助教 (40957916)
• Project Period (FY): 2022-08-31 – 2024-03-31
• Keywords: COVID-19 / 2価ワクチン / 指先採血 / 乾燥濾紙血液 / ブレイクスルー感染

Outline of Final Research Achievements

This study showed that the participants who developed breakthrough infection (BI) had lower levels of neutralizing activities compared to the controls without BI. These differences were consistently observed before and after the fifth dose of bivalent vaccine, and during not only BA.5 but also XBB sub-lineage endemic periods. Given the above results, the neutralizing activities below 50% using the 200-fold diluted sera might be one of the indicators of high risk of COVID-19 BI.
Furthermore, this study demonstrated that dried blood spot (DBS) sample collection could be used to evaluate neutralizing activities against WT and Omicron variants (BA.5 and XBB.1.5). DBS sampling has the advantages of less invasive collection (i.e., self-collection), low cost, and easy transport and storage, making it a practical alternative to blood collection via traditional venipuncture. These advantages would also make DBS appealing for use in resource-limited settings and in potential future pandemics.

Free Research Field

感染症学

Academic Significance and Societal Importance of the Research Achievements

本研究は、COVID-19感染リスクが増加する中和活性レベルが明らかにするとともに、個人および集団の免疫獲得状況を迅速かつ安定的に多検体処理可能な技術構築に取り組み、指先採血を吸収させた濾紙乾燥血液で中和活性が評価できることを見出した。指先採血は、簡便かつ感染リスクを下げられる方法として、新興感染症で必ず課題となる免疫獲得状況を広く知るための安全な手段につながり、ワクチン接種が必要な対象者の選定や最適な接種時期の計画立案など、ワクチン予防効果不透明性の課題を克服できるとともに、今後の様々な微生物へのワクチン接種計画にも応用の可能性が開ける。