Fundamental research on transmission dynamics of influenza virus in indoor environment

2023 Fiscal Year Final Research Report

• Project/Area Number: 20K04826
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 23020:Architectural environment and building equipment-related
• Research Institution: National Institute of Infectious Diseases
• Principal Investigator: Shimasaki Noriko 国立感染症研究所, ウイルス第三部, 主任研究官 (80466193)
• Co-Investigator(Kenkyū-buntansha): 石井 淳子 地方独立行政法人神戸市民病院機構神戸市立医療センター中央市民病院(第1診療部、第2診療部、第3診療部, 中央市民病院, 医長 (10704710)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: インフルエンザ / COVID-19 / ウイルス変異 / 中和抗体 / ウイルス伝播 / エアロゾル

Outline of Final Research Achievements

We conducted fundamental research to elucidate the dynamics of indoor transmission of respiratory viruses. We had monitored for a year the antibody titers of participants as an influencing factor to understand the actual situation of breakthrough infection. We found that 25% of people had breakthrough infections with COVID-19, in which the antibody titers induced by the vaccine were weakened against the epidemic strain, and in many cases it was suspected that the infection occurred at home and from the family members. On the other hand, influenza vaccine antibody titers reacted against the epidemic strain, and no breakthrough infections occurred with influenza. We verified the change of viral infectivity by indoor environmental factors such as temperature and humidity through simulated experiments and performed an aerosol experiment of generating virus model particles to investigate the diffusion dynamics of the model particles in the chamber.

Free Research Field

感染制御

Academic Significance and Societal Importance of the Research Achievements

今回100人規模の調査で、マスクや手指衛生への重要視など個人意識に関係なく、宿主の抗体価低減がCOVID-19の室内伝播感染を起こす一因であることが示唆され、ブレイクスルー感染に関する実態把握ができたことは意義深い。一方で、感染場所や経路が不明なケースも多かったことから、室内における感染源伝播動態を解明することは引き続いての課題であり、本研究で構築したウイルスモデル粒子のエアロゾル実験系によって、様々な建築材料で囲まれた空間内における、感染源の浮遊特性や付着特性が評価できるようになった。ウイルス感染性に影響を与える室内環境因子も評価できた。