New research from the Barcelona Institute for Global Health provides solid evidence that COVID-19 is a seasonal infection, linked to lower temperatures and drier air. This means COVID is similar to influenza.
The coordinator of the study, Xavier Rodó, is the director of the Climate and Health programme at ISGlobal.
“The question of whether COVID-19 is a genuine seasonal disease becomes increasingly central, with implications for determining effective intervention measures,” said Rodó.
To answer this question, the researchers looked at how COVID-19 spread in association to temperature and humidity in 162 countries in five continents. The study found that higher transmission rates coincided with lower temperatures and lower humidity.
On both global and local scales, the research showed an overall trend of COVID-19 transmissions increasing as temperatures fell. However, this pattern was broken during the summer time on all continents studied.
“This could be explained by several factors, including mass gatherings of young people, tourism, and air conditioning, among others,” explained study first author Alejandro Fontal.
Overall, this study provides important information for COVID-19 policies. This also allows scientists and healthcare workers to prepare for increases in COVID-19 transmissions connected to changes in the weather.
“Altogether, our findings support the view of COVID-19 as a true seasonal low-temperature infection, similar to influenza and to the more benign circulating coronaviruses,” said Rodó.
Importantly, the study also gives an insight into how the disease is transmitted through the air. Diseases like influenza and now COVID-19 are known to stay airborne longer as aerosol sizes decrease due to drier air. This means a focus on better ‘air hygiene.’
“This link warrants an emphasis on ‘air hygiene’ through improved indoor ventilation as aerosols are capable to persist suspended for longer times,” said Rodó.
The research is particularly relevant now, as the COVID-19 pandemic persists in the United States and many people are resisting the call to vaccinate and wear masks.
The study is published in the journal Nature Computational Science.