Meteorological factors and domestic new cases of coronavirus disease (COVID-19) in nine Asian cities: A time-series analysis

Zonglin He; Yiqiao Chin; Jian Huang; Yi He; Babatunde O. Akinwunmi; Shinning Yu; Casper J.P. Zhang; Wai-kit Ming

The significant smoothers indicated that the correlations between new cases of COVID-19 and explanatory variables were non-linear. As shown in Figure 3 , the no-lag model suggested that holding all linear and the other nonlinear terms fixed, daily new cases of COVID-19 tended to show no influence by the temperature, but the cases number decreased when temperature reached 5, 18, and 29, in Beijing, Hong Kong, and Singapore, respectively (P < 0.01 for all, Figure 3 ). While the magnitude of results might look small relative to the base rate of case accrual, these plots were on the log-case scale, so the effect on the case number is multiplicative. The distributions of COVID-19 cases displayed greater uncertainty at lower temperature in Beijing and Wuhan. Beijing and Wuhan has fluctuating patterns throughout the six models both regarding temperature and relative humidity except in lag 5d and lag 4d model for Wuhan, which might be due to the change of diagnostic method on February 12, when a total of 13,436 cases were added. Nevertheless, the relationship between relative humidity and new cases were less evident in the No-lag model, and the distributions of COVID-19 cases displayed greater uncertainty in Wuhan.