Background Coronavirus disease (COVID‐19), caused by severe acute respiratory syndrome coronavirus (SARS‐CoV‐2), has rapidly spread globally. Potentially infected individuals travel on commercial aircraft. Thus, this study aimed to investigate and test the association between the use of face masks, physical distance, and COVID‐19 among passengers and flight attendants exposed to a COVID‐19 passenger in a domestic flight. Methods This observational study investigated passengers and flight attendants exposed to COVID‐19 on March 23, 2020, on board a flight to Naha City, Japan. Secondary attack rates were calculated. Whole‐genome sequencing of SARS‐CoV‐2 was used to identify the infectious linkage between confirmed cases in this clustering. The association between confirmed COVID‐19 and proximity of passengers' seats to the index case and/or the use of face masks was estimated using logistic regression. Results Fourteen confirmed and six probable cases were identified among passengers and flight attendants. The secondary attack rate was 9.7%. Twelve of 14 SARS‐CoV‐2 genome sequences in confirmed cases were identical to that of the index case or showed only one nucleotide mutation. Risk factors for infection included not using a face mask (adjusted odds ratio [aOR]: 7.29, 95% confidence interval [95% CI]: 1.86‐28.6), partial face mask use (aOR: 3.0, 95% CI: 0.83‐10.8), and being seated within two rows from the index patient (aOR: 7.47, 95% CI: 2.06‐27.2). Conclusion SARS‐CoV‐2 was transmitted on the airplane. Nonuse of face masks was identified as an independent risk factor for contracting COVID‐19 on the airplane.

Objective: The Okinawa prefectural government conducted enhanced surveillance for the Sixth Worldwide Uchinanchu Festival, with participation of more than 5300 visitors from abroad, many of whom were Okinawan or of Okinawan descent, for early detection of Zika virus disease and other potential public health threat outbreaks. Method: Enhanced surveillance conducted from 12 October through 13 November involved four surveillance systems, (Nursery) School Absenteeism Surveillance system ((N)SASSy), Prescription Surveillance (PS), and Official Syndromic Surveillance (OSS), each of them operates routinely, in addition to case-based and sentinel surveillance under the Infectious Diseases Control Law as Official National Surveillance of Infectious Diseases (ONSID). This enhanced surveillance was conducted for analysis and evaluation, with intensive information sharing among concerned parties. Result: We performed the enhanced surveillance for 33 days from 12 October through 13 November. Information from enhanced surveillance was analyzed and evaluated, and eventually summarized as a daily report. There has been one rubella case at an elementary school in Okinawa City on 20 October and a measles case at an elementary school in Uruma City on 2 November. Those two cases were registered into (N)SASSy on a timely basis. The public health center investigated them quickly, and the measles case was denied later because symptoms did not satisfy with case definition. Discussion: How to cite this paper: Yamakawa, M., Yamauchi, M., Nidaira, M., Azuma, T., Nakasone, T., Ando, F., Hayamizu, T., Kinjo, S. and Nakamura, Y. We regard enhanced surveillance as useful to confirm events that might demand a public health response. Moreover, the related including public health centers or medical institutions confirmed the situation as valuable for the administrative structure. However, because almost all (nursery) schools or pharmacies are closed during successive holidays, outbreaks that occur on such days cannot be recognized on a timely basis. More sensitive surveillance for such days, with better preparations for ambulance transfer and at emergency departments in hospitals remains as a challenge for future work.

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