Association between meteorological factors and daily new cases of COVID-19 in 188 countries: A time series analysis

Abstract

By 31 December 2020, Coronavirus disease 2019 (COVID-19) had been prevalent worldwide for one year, and most countries had experienced a complete seasonal cycle. The role of the climate and environment are essential factors to consider in transmission. We explored the association between global meteorological conditions (including mean temperature, wind speed, relative humidity and diurnal temperature range) and new cases of COVID-19 in the whole past year. We assessed the relative risk of meteorological factors to the onset of COVID-19 by using generalized additive models (GAM) and further analyzed the hysteresis effects of meteorological factors using the Distributed Lag Nonlinear Model (DLNM). Our findings revealed that the mean temperature, wind speed and relative humidity were negatively correlated with daily new cases of COVID-19, and the diurnal temperature range was positively correlated with daily new cases of COVID-19. These relationships were more apparent when the temperature and relative humidity were lower than their average value (21.07°Cand 66.83%). The wind speed and diurnal temperature range were higher than the average value(3.07 m/s and 9.53 °C). The maximum RR of mean temperature was 1.30 under -23°C at lag ten days, the minimum RR of wind speed was 0.29 under 12m/s at lag 24 days, the maximum RR of range of temperature was 2.21 under 28 °C at lag 24 days, the maximum RR of relative humidity was 1.35 under 4% at lag 0 days. After a subgroup analysis of the countries included in the study, the results were still robust. As the Northern Hemisphere enters winter, the risk of global covid-19 remains high. Some countries have ushered in a new round of COVID-19 epidemic. Thus, active measures must be taken to control the source of infection, block transmission and prevent further spread of COVID-19 in winter.

Keywords: COVID-19; Humidity; Relative; Temperature; Wind speed.

Graphical abstract

Fig. 1

The cumulative cases of COVID-19 in the study area as of 31 December 2020.

Fig. 2

Pearson correlation coefficients between meteorological variables and daily incidence of COVID-19. TEMP: mean temperature; WS: wind speed; RT: diurnal temperature range; AH: absolute humidity; RH: relative humidity; PRCP: precipitation. *0.01 < P ≤ 0.05; **0.001 < P ≤ 0.01; P ≤ 0.001.

Fig. 3

Exposure-response curves for the effects of meteorological variables on daily new cases of COVID-19 in the single-variable model using GAM. The x-axis is the meteorological parameters. The y-axis indicates the contribution of the smoother to the fitted values.Temp: temperature; WS: wind speed; RT: diurnal temperature range; RH: relative humidity.

Fig. 4

Exposure-response curves for the effects of meteorological variables on daily new cases of COVID-19 in the multiple-variables model using GAM. The x-axis is the meteorological parameters. The y-axis indicates the contribution of the smoother to the fitted values. Temp: temperature; WS: wind speed; RT: diurnal temperature range; RH: relative humidity.

Fig. 5

Contour plots of the exposure–response relationship for the association between daily new cases of COVID-19 and meteorological variables in the single-variable model. A: mean temperature B: wind speed: wind speed C: diurnal temperature range D: relative humidity The Y-axis is the lag days ranging from 0 to 24. The X-axis is the range of the observed values of each variable. The color gradient represents the relative risk (RR). The red color gradient represents higher strength of RR, above 1, and the blue gradient represents lower strength of RR, below 1. The white color represents no difference, at RR = 1. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Fig. 6

Contour plots of the exposure-response relationship for the association between daily new cases of COVID-19 and meteorological variables in the multiple-variables model. A: mean temperature B: WIND speed: wind speed C: diurnal temperature range D: relative humidity The Y-axis is the lag days ranging from 0 to 24. The X-axis is the range of the observed values of each variable. The color gradient represents the relative risk (RR). The red color gradient represents higher strength of RR, above 1, and the blue gradient represents lower strength of RR, below 1. The white color represents no difference, at RR = 1. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Fig. 7

Contour plots of the exposure-response relationship for the association between daily new cases of COVID-19 and meteorological variables in the Southern Hemisphere. A: mean temperature B: wind speed: wind speed C: diurnal temperature range D: relative humidity The Y-axis is the lag days ranging from 0 to 24. The X-axis is the range of the observed values of each variable. The color gradient represents the relative risk (RR). The red color gradient represents higher strength of RR, above 1, and the blue gradient represents lower strength of RR, below 1. The white color represents no difference, at RR = 1. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)

Fig. 8

Contour plots of the exposure-response relationship for the association between daily new cases of COVID-19 and meteorological variables in the Northern Hemisphere. A: Mean temperature B: Wind speed: wind speed C: diurnal temperature range D: relative humidity The Y-axis is the lag days ranging from 0 to 24. The X-axis is the range of the observed values of each variable. The color gradient represents the relative risk (RR). The red color gradient represents higher strength of RR, above 1, and the blue gradient represents lower strength of RR, below 1. The white color represents no difference, at RR = 1. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.)