In a new study, researchers found that wintertime outbreaks of COVID-19 have been largely driven by whether people adhere to control measures such as mask-wearing and social distancing.
They found the climate and population immunity are playing smaller roles during the current pandemic phase of the virus.
The research was conducted by a team at Princeton University.
COVID-19 Cases have climbed in many northern hemisphere locations since November.
In the United States, spikes in COVID-19 cases are thought to be tied to increased travel and gatherings for Thanksgiving and Christmas.
Notably, outbreaks were recorded in temperate locations such as Los Angeles in addition to regions with much colder conditions.
At the same time, large outbreaks were observed in South Africa from November to January, which is the country’s summer months.
In the study, the team ran simulations of a wintertime coronavirus outbreak in New York City to identify key factors that would allow the virus to proliferate.
They found that relaxing control measures in the summer months led to an outbreak in the winter regardless of climate factors.
They also found that even maintaining rigid control measures through the summer can lead to a wintertime outbreak if climate factors provided enough of a boost to a viral transmission.
But having effective control measures in place last summer could have limited the winter outbreaks now.
The results implied that lax control measures—and likely fatigue with complying with control measures—would fuel wintertime outbreaks.
One author of the study is Rachel Baker, an associate research scholar.
The study is published in Nature Communications.