Studies needed on wider spread in colder weather

PETALING JAYA: The jury is out on whether the coronavirus will spread even more in a cooler climate.

While cold weather may lead to increased transmission of coronaviruses, more research is needed to ascertain if this is true of Covid-19, said Malaysian medical experts.

Epidemiologist Prof Dr Awang Bulgiba Awang Mahmud (pic) of Universiti Malaya said some experts had theorised that colder weather might make the infections spread more easily due to drier air.

“Colder air tends to hold less moisture and the use of heaters in the winter dries the air as well.

“Theoretically, drier air causes droplets to become smaller, making them capable of remaining suspended in the air longer.

“Drier air also causes the mucus and cilia (tiny hairs that line a person’s air passages) in our respiratory tract to become less effective,” he said.

Some experts, he added, had also posited that virus outbreaks in countries with temperate climates would be more localised during winter as more people might remain indoors at the time.

Dr Awang Bulgiba, however, cautioned that such theories had not yet been proven of SARS-CoV-2, the coronavirus that causes Covid-19, and more research was needed.

“We do not yet have the benefit of a full year of the pandemic to study this.

“If Covid-19 were to follow the pattern of SARS (Severe Acute Respiratory Syndrome), we may see a winter peak but no one can say for certain at the moment,” he said.

In theory, he stressed, the virus was less likely to survive in high temperatures, but other factors also affected the virus’ transmissibility and infectivity.

“For example, it has not been proven in the United States as the pandemic picked up in the summer.

“Summer was rather hot in the US this year, but it does not appear to have stopped the virus in California and Florida.

“The problem with these kinds of observational data is that there are many confounding factors at play here and the most important one is compliance with public health measures,” he explained.

Malaysia, he added, usually did not see a drastic change in temperature and humidity throughout the year.

“During the monsoon season, there is a drop in temperature, but not to the extent that we are forced to use heaters at home, so it is unclear if this will affect Covid-19 transmission.

“If we keep the borders closed and visitors from colder climates are unable to come to Malaysia without being quarantined, I do not think imported cases from cooler climates will cause a spike,” he said.

Universiti Putra Malaysia epidemiologist Assoc Prof Dr Malina Osman said evidence had shown that cooler temperatures did have an effect on coronaviruses.

“Cold weather does significantly prolong the viability of viruses, therefore allowing higher risk of transmission.

“Studies have been conducted on various viruses, including the coronavirus that was responsible for SARS in Hong Kong,” she said, adding that this, though, remained to be seen for Covid-19.

Dr Malina said the virus transmission in Malaysia might not be directly affected by weather patterns, though it might be affected by international travel.

“If international travel is eased by the end of this year, caution must be recommended for those who wish to travel to areas with colder climates,” she said.

Universiti Malaya virologist Prof Dr Sazaly Abu Bakar said the coming winter in the northern hemisphere was not likely to have a bearing on the Covid-19 situation in Malaysia.

“There was no impact on us either during the winter in the southern region such as Australia and New Zealand,” he said.

Health director-general Tan Sri Dr Noor Hisham Abdullah said the ministry was making preparations for a possible increase in infections in view of the coming winter months in other parts of the world.

There have been many media reports addressing the issue about the possibility of the pandemic worsening during the colder months.AP quoted World Health Organisation’s top official in Europe Dr Hans Kluge as saying that autumn presented a “tricky situation” because of schools reopening, the onset of the flu season, and increased mortality among older people during winter months in general.

American lifestyle magazine The Atlantic, meanwhile, noted that data on the coronavirus’ circulation during winter is scant but other respiratory viruses, such as influenza, tend to spread more readily in the winter than the summer.

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