Kenyan researcher claims Covid-19 is seasonal


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The virus that causes Covid-19, just like the viruses that cause the flu, is seasonal and will die down when summer, characterised by higher temperatures and humidity, sets in.

This is according to a Kenyan researcher based in the United States, who has marshalled data that shows that the majority of the cases of Covid-19 have been recorded in the temperate climates, above the Tropic of Cancer.

In an e-mail to the Nation, Farouk Juma pointed out that 93 per cent of all the cases are in areas beyond the Tropic of Cancer, which experience little sunlight and cold drier air that is more conducive to airborne viruses. This allows them to survive longer outside the human body and travel further between hosts.

Spain and Italy, which have recorded extremely high confirmed cases and deaths from Covid-19, are in this region.

In the email, Mr Juma added that the region also experiences “more clustering of people indoors due to the cold”.

This assertion has been floating around. US President Donald Trump has previously suggested that Sars-CoV-2 — the virus that causes Covid-19 — will go away on its own in the warmer weather. Many have suggested that this was the same case with other coronaviruses, such as the Sars-CoV in 2003.


The University of Connecticut modellers published a paper in which they said that ultraviolet (UV) rays in the sun’s electromagnetic spectrum damage viruses. It is no wonder then that President Trump asked scientists to expose the body to UV light.

But experts urged caution because UV harms the skin when it is above certain levels. UV lamps are used to sterilise the air in operating theatres.

However, some scientists say it’s not enough that there will be a hot period. Marc Lipsitch, Professor of Epidemiology and Director of the Center for Communicable Disease Dynamics at the Harvard School of Public Health said that they expect modest declines in the contagiousness of Sars-CoV-2 in warmer, wetter weather.

He added that these declines alone will not slow transmission enough to change the number of deaths and infections tremendously.

Prof Lipsitch added that Sars-CoV did not die of natural causes in 2003, but of extremely intense public health interventions in mainland Chinese cities, Hong Kong, Vietnam, Thailand, Canada and elsewhere where the virus travelled to.

Omu Anzala, a professor of viruses at the University of Nairobi, said that while UV from the sun has been shown to destroy viruses, the data available is provisional and [too] limited to make conclusions on whether Sars-CoV-2 will be seasonal or not.

“This virus has been with us for how long? Five months? It has not even completed a year for us to see a spike or a tapering,” the professor said.

He said comparisons of the seasonality of viruses are made for influenzas. He explained: “While Sars-CoV-2 is a coronavirus, it is very different from the viruses that cause influenza.”

Prof Anzala, who has studied the strains of influenzas that circulate in Kenya, also said that they are not as seasonal in Kenya as they are in the US or Europe. “Flu here is sustained throughout the year,” he said.

Lab studies in the United States, Vietnam and here in Kenya have shown that humidity strongly affects flu transmission, and this occurs even more favourably when the air is drier.
However, influenza viruses were the subjects of these studies and not the other coronaviruses.

“Sars-CoV-2 shares characteristics with these influenza viruses that were in these studies, such as mode of transmission, causing fever and respiratory illnesses, but we have to remember they are very different,” Prof Anzala said.

It can also be argued that people have less vitamin D in their system during the cold weather.

Vitamin D, a great contributor to a strong immune system, depends in part on UV light exposure, which is higher when there is sunlight.

Kamlesh Khunti, professor of primary care diabetes and vascular medicine from the Diabetes Research Centre at Leicester General Hospital in the United Kingdom, found that UV light was most strongly associated with lower Covid-19 growth rates.

However, virology Professor Thumbi Ndung’u, based in South Africa, argued that this does not explain why African Americans who have higher levels of vitamin D are dying more than the others.

Gitahi Githinji, the director of AMREF Health Africa, which has participated in the response to Covid-19 in Kenya and Africa, said that there are many factors that influence the spread of the virus and not just environmental factors.

He encouraged the public to observe the public health interventions that have been put in place.

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