A Canadian study surveyed 144 geopolitical areas (states and provinces in Australia, USA and Canada, as well as various countries around the world) and a total of more than 375.600 confirmed cases of COVID-19. China, Italy, Iran, and South Korea were excluded because the virus was in decline in China's case or in full pandemic at the time of analysis in others.
To estimate the growth of the pandemic, the researchers compared the number of cases on March 27 with cases on March 20, 2020. They then determined the coronavirus influence of climate, latitude, temperature, humidity, school closures, mass meeting restrictions and social distance measured during the exhibition period from 7 to 13 March.
The results seem to leave little room for interpretation: little or no association between latitude or temperature with the epidemic growth of COVID-19. Only a weak association between moisture and reduced virus transmission. The results, especially those showing the influence of warmer weather on the progression of the pandemic, surprised the authors.
"We had conducted a preliminary study that both latitude and climate could play a role in the coronavirus", says Dr. Peter Jüni. "But when we repeated the study under much stricter conditions, we got the opposite result."
The researchers found that public health measures, including school closures, social distancing, and restrictions on large gatherings, were effective.
"Our findings are of immediate relevance as many countries, and some Canadian provinces and territories, are considering loosening or removing some of these public health interventions," says Jüni.
"Summer won't make it disappear",
This is what Prof.ssa says Dionne Gesink, co-author and epidemiologist of the Dalla Lana School of Public Health. “It is important that people know this. On the other hand, the more public health interventions that have taken place in an area, the greater the impact on slowing epidemic growth. These containment measures are really important because they are the only thing that works right now to slow the epidemic “.
The authors note several study limitations, such as differences in testing practices, the inability to estimate actual COVID-19 rates, and adherence to social distancing.
When deciding how to lift restrictions, governments and public health authorities should carefully weigh the impact of these measures with respect to the potential harm and benefits to mental and economic health.
Publication: Impact of climate and public health interventions on the COVID-19 pandemic. A prospective cohort study.
Peter Jüni, Martina Rothenbühler, Pavlos Bobos, Kevin E. Thorpe, Bruno R. da Costa, David N. Fisman, Arthur S. Slutsky and Dionne Gesink
CMAJ 08 May 2020 cmaj.200920; DOI: https://doi.org/10.1503/cmaj.200920 http://www.cmaj.ca/lookup/doi/10.1503/cmaj.200920