MONDAY, May 11, 2020 (HealthDay News) -- For COVID-19, epidemic growth is not associated with latitude and temperature or with absolute humidity, according to a study published online May 8 in CMAJ, the journal of the Canadian Medical Association.
Peter Jüni, M.D., from the Applied Health Research Center in Toronto, and colleagues performed a prospective cohort study of 144 geopolitical areas worldwide with at least 10 COVID-19 cases and local transmission by March 20, 2020 (total of 375,609 cases). The associations between epidemic growth and latitude, temperature, humidity, school closures, restrictions of mass gatherings, and measures of social distancing during an exposure period 14 days previously were examined.
In univariate analyses, the researchers observed few or no associations between epidemic growth and latitude and temperature, while weak negative associations were seen for relative humidity and absolute humidity (ratio of rate ratios [RRRs], 0.91 per 10 percent and 0.92 per 5 g/m³). There were strong associations for restrictions of mass gatherings, school closures, and measures of social distancing (RRRs, 0.65, 0.63, and 0.62, respectively). In multivariable analyses, a strong association was seen with the number of implemented public health interventions, while the association with absolute humidity was no longer statistically significant.
"These findings suggest that seasonality is likely to play only a minor role in the epidemiology of COVID-19, while public health interventions (school closures, restricting mass gatherings, social distancing) appear to have a major impact," the authors write.