Number of public health nurses and COVID-19 incidence rate by variant type: an ecological study of 47 prefectures in Japan.

"Declarations Ethics approval and consent to participateBecause this study has used anonymized public data, it is exempt from the implementation of informed consent and the approval of the Institutional Review Board. Consent for publicationNot applicable. Availability of data and materialsAll data used in this study are publicly available. Data can be downloaded from following websites: the number of COVID-19 cases (https://www.mhlw.go.jp/stf/covid-19/kokunainohasseijoukyou.html) and the number of public health nurses (https://www.mhlw.go.jp/toukei/list/36-19.html). Details of the data source of each variable adopted as a covariate in this study are presented in Additional file 2. Competing interestsK.S. received research grants from YKK AP Inc.; Ushio Inc.; Tokyo Electric Power Company; En-viroLife Research Institute Co., Ltd.; Sekisui Chemical Co., Ltd.; LIXIL Corp.; and KYOCERA Corp. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results. The other authors declare no conflicts of interest. FundingThis work was supported by the COVID-19 Countermeasure Research Grant from the Japanese Society of Public Health (no grant number) and the Center Research Expense of Nara Medical University (no grant number). Authors’ contributionsKT conceived the study design, collected the data, performed statistical analyses, and drafted the manuscript. MS conceived the study design. KS performed statistical analyses. All authors discussed the results and contributed to the final manuscript. All authors read and approved the final manuscript. AcknowledgementsWe would like to thank healthcare workers, public health officials, and all other essential workers for their efforts in combating the spread of COVID-19. We also thank Dr. Heather Hill for her English language editing. Competing interests K.S. received research grants from YKK AP Inc.; Ushio Inc.; Tokyo Electric Power Company; En-viroLife Research Institute Co., Ltd.; Sekisui Chemical Co., Ltd.; LIXIL Corp.; and KYOCERA Corp. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript, or in the decision to publish the results. The other authors declare no conflicts of interest."

"Funding This work was supported by the COVID-19 Countermeasure Research Grant from the Japanese Society of Public Health (no grant number) and the Center Research Expense of Nara Medical University (no grant number)."