Fig. 1.

Trends in difficult-to-transfer patients in emergency medical services in relation to the waves of COVID-19 and heat illness in Tokyo between March and September 2020.

Data on the number of heat illness patients were obtained from Fire and Disaster Management Agency [2]; data on the number of coronavirus disease (COVID-19) patients (total and severe) and difficult-to-transfer patients were derived from the Tokyo Metropolitan Government [8]. We calculated and indicated 7-day moving average for the number of COVID-19 patients and difficult-to-transfer patients.

*For heat illness patients, weekly total number was the only available data (Monday to Sunday); therefore, daily average number in each week was calculated (indicated as a bar chart) on the midweek days (Thursday).

†Data on severe cases in March and April were not available because the definition of “severe” was determined on 27 April 2020.