- A new study suggests that warm weather and increased humidity will probably not be effective in stopping the spread of COVID-19.
- But public health measures like school closures and social distancing do appear to help.
- Experts say people need to be smart in how these measures are eventually lifted in order to prevent a surge in the disease.
- Physical or social distancing may need to continue for at least a year.
All data and statistics are based on publicly available data at the time of publication. Some information may be out of date.
A new study published in the Canadian Medical Association Journal suggests that the arrival of warm weather probably won’t stop the spread of COVID-19 as had been previously hoped.
This same study, however, seems to indicate that public health measures like school closures and limitations on gathering sizes are helping.
According to study author Dr. Peter Jüni, Institute for Health Policy, Management and Evaluation, University of Toronto and St. Michael’s Hospital, the goal of the study was to investigate whether the spread of COVID-19 would be slowed down as we progress into the warmer, more humid months of the year.
Jüni said it is well known that the flu behaves in this way, and it was thought that perhaps COVID-19 would as well.
The study included 144 geopolitical areas, including states and provinces in Australia, Canada, and the United States, as well as various other countries.
Altogether, 375,600 confirmed cases of COVID-19 were included in the study.
China, Iran, Italy, and South Korea were not included, however.
China was excluded because the virus was waning at the time of the study.
Iran and Italy were excluded because the disease was in full outbreak at the time.
In order to estimate the growth of the disease, the researchers compared the number of cases on March 20 with the number of cases on March 27.
They then looked at how latitude, temperature, and humidity affected epidemic growth.
In addition, they examined how public health measures during the exposure period of March 7 to 13 — like social distancing, restriction of large gatherings, and school closures — influenced epidemic growth.
When the researchers analyzed the data, they found little or no association between epidemic growth and latitude and temperature.
Humidity was only weakly associated with reduced transmission of the disease.
However, a strong link existed between reduced disease transmission and various physical or social distancing measures, like school closures and limiting of large gatherings.
Also, implementing more of these measures was strongly linked with reduced spread of the disease.
Based on these results, Jüni said, “It’s quite unlikely that temperature will play a role in controlling the pandemic.
“The role of humidity is unclear, but our data suggest that it will be minor at best.”
However, restrictions on mass gatherings, school closures, and physical distancing all appear to play an important role in stemming the spread of the disease, he said.
In fact, the data suggests that implementation of at least two of these interventions could reduce epidemic growth by an average of 30 percent, Jüni said.
According to Brian Labus, PhD, MPH, assistant professor at the School of Public Health at the University of Nevada in Las Vegas, temperature and humidity do play a role in the survival of the virus, but this only plays a small role in its transmission.
“The biggest driver of disease transmission is our behavior,” he explained.
“This study found exactly that. Temperature and humidity really didn’t mean much for disease transmission, but our implementation of social distancing did.”
While many people are eager to get to back to “normal” life, Jüni suggests that we need to be “smart and creative” in how we do this in order to avoid another surge of cases.
“We all need to get ready now for a marathon,” Labus said, adding that we will probably have to follow physical distancing principles for at least another year.
In deciding when to ease restrictions, Labus said we need to keep in mind that all communities are not the same.
“Decisions need to be based on what is happening with disease in that community, and it doesn’t matter what other places are doing at that time,” he said.
Labus suggested that these decisions need to be driven by data rather than public or economic pressure.
“If you don’t use the disease data to guide your decision-making, it shouldn’t be a surprise if your decisions don’t work out the way you hoped they would,” he said.
The most important thing to take away from this study, according to its author, is that summer is not going to solve the problem of COVID-19.
However, the good news is that all the steps being taken with physical distancing, limiting gathering sizes, and closing schools are working.
But controlling the pandemic may be more of a marathon than a sprint. Physical distancing may have to be practiced for at least another year.