Coronavirus cases may ease in summer before re-emerging in winter, experts say

Pedestrians, wearing protective facemasks amid concerns of the novel coronavirus outbreak, cross a street in Hanoi on February 7, 2020. (Photo by Manan VATSYAYANA / AFP) (Photo by MANAN VATSYAYANA/AFP via Getty Images)
Pedestrians wear protective face masks amid concerns of the coronavirus in Hanoi on 7 February. (Getty)

The deadly coronavirus may ease in summer before re-emerging in the cold winter months, experts have said.

After being discovered at the end of last year, the previously unknown strain has spread well beyond its epicentre in the Chinese city Wuhan.

More than 31,500 cases have been confirmed globally, according to John Hopkins University.

While 31,207 are in China, the disease has crossed national borders into at least 25 countries, including the US, Canada and Australia.

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Three cases have been confirmed in the UK.

In the most severe incidences, victims succumb to pneumonia, with the death toll reaching 636 on Friday.

Virtually unheard of a month ago, little is known about the new strain, leaving experts wondering how the outbreak will play out.

How could the new coronavirus change with the seasons?

For now, the new strain appears to only spread via droplets expelled from an infected person as they cough or sneeze.

It is unknown whether the virus can survive “floating” in the air or on hard surfaces.

Despite the various mysteries, viruses in general tend to peak in cold winter months and ease as the weather warms up.

When asked whether the new coronavirus may ebb and flow, Professor Paul Hunter - from the University of East Anglia, said: “Droplets spread infections more in winter in the northern hemisphere.

“The number of cases may reduce in summer and re-emerge in winter.”

The new coronavirus strain, 2019-nCoV, is one of seven that are known to infect humans.

Coronaviruses can cause everything from the common cold to severe acute respiratory syndrome (Sars), which killed 774 people during its 2004 outbreak.

Authorities were famously tight-lipped about Sars, not informing the World Health Organization until three months after it emerged, when 305 cases - and five deaths - had occurred across six districts in the region Guangdong.

By March 21, suspected and probable cases reached 350 - including 10 deaths - in 13 countries.

On March 31, 1,622 people were infected, of which 58 died.

Nonetheless, a global effort meant Sars was contained after around eight months.

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“Sars largely spread in hospitals but still died out in the summer in the northern hemisphere,” said Professor Hunter.

As to why this occurs, Professor John Edmunds - from the London School of Hygiene & Tropical Medicine - notes school term times may play a big role.

“We know very little about respiratory viruses in general,” he said.

“They tend to be more common in winter, which may be because of schools opening and closing.”

Colds and flu are thought to become a bigger risk in winter due to icy weather driving people to huddle close together indoors.

There is also evidence low temperatures and a lack of sunlight slows the rate norovirus, the winter vomiting bug, breaks down.

How similar is the new coronavirus to Sars?

As to concerns the new coronavirus may re-emerge when the weather turns chilly, this did not occur with Sars, with no cases being reported since 2004.

The two coronaviruses share similarities, but also have distinct differences.

“Sneezing and diarrhoea is less common with the new strain than with Sars,” said Professor Hunter.

Patients are tending to develop flu-like symptoms, like fever and coughing.

Scientists from Fudan University in Shanghai found, however, the new strain appears to be 89.1% genetically similar to “a group of Sars-like coronaviruses”.

With Sars having started in bats, this suggests the nocturnal creatures may also be responsible for the new coronavirus.

The strain is thought to have “jumped” from an animal to a human at the end of last year.

Most of those who initially became unwell worked at or visited a seafood and live animal market, which reportedly sold everything from hedgehogs to donkeys.

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A team from the Chinese Academy of Sciences in Wuhan also analysed the viral DNA of five coronavirus patients.

They found the new strain seems to share 79.5% of its genetics with Sars and is 96% “identical” to a coronavirus that infects bats.

Speaking at the time, Professor Ian Jones from the University of Reading, said: “2019-nCoV is a bat virus and Sars is the closest relative seen previously in people.

“In essence, it’s a version of Sars that spreads more easily but causes less damage.

“The virus also uses the same receptor, the door used to get into human cells, which explains transmission and why it causes pneumonia.”

Sars jumped from bats to humans via the masked palm civet, a mammal native to the Indian subcontinent and south-east Asia.

Scientists from Peking University in Beijing have suggested snakes may have been the “intermediate host” for the new coronavirus.

A team from South China Agricultural University have since found pangolins could be to blame.

SEOUL, SOUTH KOREA - FEBRUARY 7, 2020: A royal guard in a medical mask by the Deoksugung Palace in central Seoul. The Chinese authorities registered an outbreak of the 2019-nCoV coronavirus in Wuhan in December 2019; as of February 7, 2020, the number of people infected with the new strain of coronavirus has risen over 30,000, the death toll is over 600. Stanislav Varivoda/TASS (Photo by Stanislav Varivoda\TASS via Getty Images)
A royal guard wears a medical mask by the Deoksugung Palace in central Seoul on 7 February. (Getty)

How does the new coronavirus kill patients?

Pneumonia comes about when a respiratory infection causes the alveoli (air sacs) in the lungs to become inflamed and filled with fluid or pus, according to the American Lung Association.

The lungs then struggle to draw in air, resulting in reduced oxygen in the bloodstream.

“Without treatment the end is inevitable,” said the charity Médecins Sans Frontières.

“Deaths occurs because of asphyxiation.”

The US Centers for Disease Control and Prevention has warned there is no specific treatment for coronaviruses.

If the infection triggers pneumonia, doctors work to combat the complication.

Pneumonia is generally caused by bacteria, which tend to respond to antibiotics.

When a virus is to blame – like 2019-nCoV – it may be treated via “antiviral medication”, according to the American Lung Association.

Professor Peter Horby from the University of Oxford claims, however, there is “no effective anti-viral”, with treatment being “supportive”.

“Doctors keep patients alive until their own body fights off the infection,” added Professor Hunter.