Random forest regression on joint role of meteorological variables, demographic factors, and policy response measures in COVID-19 daily cases: global analysis in different climate zones

Abstract

Different sources of factors in environment can affect the spread of COVID-19 by influencing the diffusion of the virus transmission, but the collective influence of which has hardly been considered. This study aimed to utilize a machine learning algorithm to assess the joint effects of meteorological variables, demographic factors, and government response measures on COVID-19 daily cases globally at city level. Random forest regression models showed that population density was the most crucial determinant for COVID-19 transmission, followed by meteorological variables and response measures. Ultraviolet radiation and temperature dominated meteorological factors, but the associations with daily cases varied across different climate zones. Policy response measures have lag effect in containing the epidemic development, and the pandemic was more effectively contained with stricter response measures implemented, but the generalized measures might not be applicable to all climate conditions. This study explored the roles of demographic factors, meteorological variables, and policy response measures in the transmission of COVID-19, and provided evidence for policymakers that the design of appropriate policies for prevention and preparedness of future pandemics should be based on local climate conditions, population characteristics, and social activity characteristics. Future work should focus on discerning the interactions between numerous factors affecting COVID-19 transmission. Supplementary Information The online version contains supplementary material available at 10.1007/s11356-023-27320-7.

Assessing eco-geographic influences on COVID-19 transmission: a global analysis

“…There was a nonlinear relationship between ambient temperature and morbidity. We found that the threshold was around 10–25 °C, which is similar to other global studies 70 , 77 . Recognizing a specific temperature threshold can serve as a triggering factor for early warning of COVID-19 78 .…”

“…In our study, the importance of relative humidity ranks last among all meteorological variables, indicating that relative humidity may be a secondary determinant of local transmission of COVID-19. Similar findings have also been concluded in epidemiological studies 70 . The results show that in continental areas, the impact of relative humidity on the spread of COVID-19 exhibits a "U" shape, which is consistent with other studies 70 .…”

“…Similar findings have also been concluded in epidemiological studies 70 . The results show that in continental areas, the impact of relative humidity on the spread of COVID-19 exhibits a "U" shape, which is consistent with other studies 70 . In island countries such as Japan and the Philippines, there is a positive correlation between relative humidity and the spread of COVID-19.…”

“…The model showed an increase in solar radiation within a certain range leads to a significant decrease in the daily number of cases, consistent with laboratory studies showing that UV light can deactivate viruses in the air and on surfaces 97 . Our findings are reinforced by multiple studies 70 , 98 . Excessive solar radiation, however, can limit potential human activities 97 .…”

“…Additionally, a meta-analysis showed that 41% of COVID-19 patients suffered from vitamin D deficiency and 42% had an insufficient vitamin D level 98 . The regular exposure to sunlight can facilitate the production of vitamin D, thereby strengthening human immune system and resilience against viral infections 70 .…”