AUTHOR=Hayashi Katsuma , Kayano Taishi , Anzai Asami , Fujimoto Marie , Linton Natalie , Sasanami Misaki , Suzuki Ayako , Kobayashi Tetsuro , Otani Kanako , Yamauchi Masato , Suzuki Motoi , Nishiura Hiroshi 

TITLE=Assessing Public Health and Social Measures Against COVID-19 in Japan From March to June 2021

JOURNAL=Frontiers in Medicine

VOLUME=9

YEAR=2022

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2022.937732

DOI=10.3389/fmed.2022.937732

ISSN=2296-858X

ABSTRACT=<sec><title>Background</title><p>Public health and social measures (PHSM) against COVID-19 in Japan involve requesting the public to voluntarily reduce social contact; these measures are not legally binding. The effectiveness of such PHSM has been questioned with emergence of the SARS-CoV-2 Alpha variant (B.1.1.7), which exhibited elevated transmissibility.</p></sec><sec><title>Materials and Methods</title><p>We investigated the epidemic dynamics during the fourth epidemic wave in Japan from March to June 2021 involving pre-emergency measures and declaration of a state of emergency (SoE). We estimated the effective reproduction number (<italic>R</italic><sub><italic>t</italic></sub>) before and after these interventions, and then analyzed the relationship between lower <italic>R</italic><sub><italic>t</italic></sub> values and each PHSM.</p></sec><sec><title>Results</title><p>With implementation of pre-emergency measures (PEM) in 16 prefectures, the <italic>R</italic><sub><italic>t</italic></sub> was estimated to be &lt; 1 in six prefectures; its average relative reduction ranged from 2 to 19%. During the SoE, 8 of 10 prefectures had an estimated <italic>R</italic><sub><italic>t</italic></sub> &lt; 1, and the average relative reduction was 26%–39%. No single intervention was identified that uniquely resulted in an <italic>R</italic><sub><italic>t</italic></sub> value &lt; 1.</p></sec><sec><title>Conclusion</title><p>An SoE can substantially reduce the <italic>R</italic><sub><italic>t</italic></sub> and may be required to curb a surge in cases caused by future SARS-CoV-2 variants of concern with elevated transmissibility. More customized interventions did not reduce the <italic>R</italic><sub><italic>t</italic></sub> value to &lt; 1 in this study, but that may be partly attributable to the greater transmissibility of the Alpha variant.</p></sec>