Correlation of ambient temperature and COVID-19 incidence in Canada

Abstract

The SARS-CoV-2 is a novel coronavirus identified as the cause of COVID-19 and, as the pandemic evolves, many have made parallels to previous epidemics such as SARS-CoV (the cause of an outbreak of severe acute respiratory syndrome [SARS]) in 2003. Many have speculated that, like SARS, the activity of SARS-CoV-2 will subside when the climate becomes warmer. We sought to determine the relationship between ambient temperature and COVID-19 incidence in Canada. We analyzed over 77,700 COVID-19 cases from four Canadian provinces (Alberta, British Columbia, Ontario, and Quebec) from January to May 2020. After adjusting for precipitation, wind gust speed, and province in multiple linear regression models, we found a positive, but not statistically significant, association between cumulative incidence and ambient temperature (14.2 per 100,000 people; 95%CI: −0.60–29.0). We also did not find a statistically significant association between total cases or effective reproductive number of COVID-19 and ambient temperature. Our findings do not support the hypothesis that higher temperatures will reduce transmission of COVID-19 and warns the public not to lose vigilance and to continue practicing safety measures such as hand washing, social distancing, and use of facial masks despite the warming climates.

UV, ozone, and COVID-19 transmission in Ontario, Canada using generalised linear models

“…It is therefore hypothesized that COVID-19 transmission may behave similarly and may decrease or even disappear when temperature and UV radiation increase in the summer. However, we previously found no association between temperature and COVID-19 incidence ( To et al, 2020 ). UV may inactivate COVID-19 as it does with coronaviruses including SARS-CoV-1 ( Tsunetsugu-Yokota, 2008 ) and MERS-CoV ( Bedell et al, 2016 ; Rutala and Weber, 2020 ), as shown under laboratory conditions and in a certain dose range (200–280 nm).…”

Weather Variability and COVID-19 Transmission: A Review of Recent Research

“…Of these studies, four studies were a global analysis of weather variables—two assessing distribution globally [ 29 , 30 ] and one evaluating association in 166 COVID-19 affected countries excluding China [ 31 ], and an early analysis of 100 affected countries [ 32 ]. The remaining articles were at the continent, country, state or city level ( n = 19/23) and included three from North America: one from New York, USA [ 33 ], one from Canada [ 34 ], and the third included selected counties in USA [ 35 ]. Four studies from China were included, two at the city level [ 36 , 37 ] and two at the provincial level [ 38 , 39 ], two studies were based in South America—one including multiple countries [ 40 ] the second focusing on Brazil [ 41 ].…”

“…From all 23 articles evaluating the association between temperature and COVID-19, three studies reported no significant association—one study based in Canada, one from Spain and the other from New South Wales (NSW), Australia ( Table 1 ). The authors reported no significant association between temperature and new daily cases [ 34 , 42 , 48 ]. An optimal temperature range is suggested in Bukhari et al where the majority of new cases were reported in regions, with the mean temperature recorded between 0–17 °C, while cases for the same period were lower in warm regions (i.e., mean temperature >17 °C).…”

“…Wind speed was included or mentioned in ten studies (43.5%). Wu et al, Xie and Zhu and To et al included wind speed in the model as a confounder and no results were reported [ 31 , 34 , 37 ]. Of the remaining seven studies, including wind speed as a weather variable, three reported significant associations between wind speed and COVID-19 cases.…”

Influence of air pollution and meteorological factors on the spread of COVID-19 in the Bangkok Metropolitan Region and air quality during the outbreak

“…It has been reported that a 1°C increase in temperature was related to a 3.08% reduction in daily new cases ( Wu et al, 2020 ) and to a drop of –14.2% in the number of confirmed cases ( Islam et al, 2020 ); in Brazil, this temperature increase was linked to a drop of –4.90% in the number of daily COVID-19 cases ( Prata et al, 2020 ). It has recently been reported that no evidence could be found to support the hypothesis that temperature can reduce the transmission of COVID-19 cases ( To et al, 2021 ). Our results showed a positive association between the temperature with the daily confirmed number of COVID-19 cases (which was statistically significant), so that higher temperature resulted in a greater number of COVID-19 cases.…”