**5. Conclusions**

Although COVID-19 is a serious concern, our study showed that it was not the main pathogen responsible for respiratory tract infections among HCWs. Symptoms associated with SARS-CoV-2 and other respiratory viral etiologies are frequently shared. While it is important to continue regular screening and testing for COVID-19 among this high-risk population, efforts should also focus on ensuring that HCWs have access to rapid molecular tests for other common respiratory illnesses.

**Author Contributions:** Conceptualization, K.A.A., C.S., A.M.G.V., and S.S.; data curation, A.M.G.V., S.M.H, and C.S.; formal analysis, K.A.A., A.M.G.V, S.M.H., and C.S.; funding acquisition, C.S. and K.A.; investigation, A.M.G.V., S.S., A.R.S., J.L., A.C.U., J.S., and A.C.C.; methodology, A.M.G.V., C.S., K.A., and L.-M.Y.; project administration, S.S., A.M.G.V., A.R.S., J.L., A.C.U., J.S., and R.S.; supervision, K.A., L.-M.Y., and C.S.; visualization, K.A.A. and C.S.; writing—original draft, K.A.A. and C.S.; writing—review and editing, K.A.A., A.M.G.V., A.R.S., J.L., S.M.H., A.C.C., S.S., A.C.U., J.S., R.S., L.-M.Y., K.A., and C.S. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was partly funded by Nagasaki University (salary support for K.A.A., A.M.G.V., S.M.H., S.S., A.C.C., K.A., L.-M.Y., and C.S.).

**Institutional Review Board Statement:** This study was conducted according to the guidelines of the Declaration of Helskinki, and approved by the San Lazaro Hospital—Research Ethics and Review Unit (Ref: SLH-RERU-2020-022-I) and the School of Tropical Medicine and Global Health, Nagasaki University Ethical Committee (NU\_TMGH\_2020\_119\_1).

**Informed Consent Statement:** Informed consent was obtained from all subjects involved in the study.

**Conflicts of Interest:** The authors declare no conflict of interest. The funder of the study did not play any role in the conceptualization and design of the study, collection, analysis and interpretation of data, writing of the manuscript or in the decision to publish the results.
