However, even secondary factors like weather and air quality can significantly impact the number of infections and deaths from the COVID-19 pandemic
During the initial years of the COVID-19 pandemic, some experts pitched warm and humid weather conditions to be conducive to the transmission of the virus. But the World Meteorological Organization (WMO) dismissed the apprehensions on May 17, 2023, saying that available evidence does not indicate weather conditions play a dominant role in disease spread.
“There has been no evidence that certain weather conditions (for example, warm and humid conditions) absolutely preclude transmission, as had been suggested by some commentators early in the pandemic,” said a report by WMO’s COVID-19 task team.
However, meteorology and air quality have played a secondary role in transmitting the pandemic, the report added. Analyses from the first two and a half years of the pandemic suggest that the influence of meteorology and air quality on disease transmission has been secondary compared to the impact of non-pharmaceutical interventions, vaccination campaigns, changing immunity profiles, the mutation in variants and behavioural dynamics, it added.
However, even secondary factors can significantly impact the number of infections and deaths from the COVID-19 pandemic. So, researchers must continue to study the role of such elements in virus spread to bolster pandemic preparedness and response, the document noted.
The WMO constituted the expert group in September 2020. At the time, there were theories that if COVID-19 continued for a few years, it would develop seasonality like other viral respiratory illnesses, especially in cold and temperate locations.
Some experimental data suggested viruses had a better chance of surviving in cold and dry environments. Previous experience with illnesses like influenza also indicated that the disease would suffer winter spikes, particularly in countries with milder temperatures.
This notion was further supported by the comparatively low frequency of the disease in Africa and other tropical areas, at least in terms of known infections.
Similar studies from other respiratory illnesses revealed that air pollution might exacerbate the symptoms brought on by COVID-19 infection and perhaps increase death risks.
When the pandemic was still active in much of the world in March 2021, the expert panel submitted its initial findings. Even then, it had been stated that climatic conditions could only play only a minor supportive role in the spread of the virus.
WMO, in its latest report, has reiterated its earlier notions. Overall, the existing literature provided evidence for possible associations between temperature and humidity and COVID-19 incidence. But these associations are complex and likely non-linear, it said.
“The specific findings of these studies are complex and will continue to be examined in coming years,” said task team chair Dr Ben Zaitchik in a press release.
Notwithstanding the nuance of those results, it is clear that researchers and the public have learned a tremendous amount about how environmental data can and cannot be used when predicting the spread of a respiratory virus, Zaitchik added.
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