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Infectious Diseases

Updated 17 September 2020

Will Covid-19 become seasonal like influenza?

While scientists predict that Covid-19 will become a seasonal virus, it won’t happen soon.

  • As SARS-Cov-2 is still causing infections, many people are wondering about its future
  • One hypothesis is that it might become seasonal, like the flu and viruses that cause the common cold
  • However, strong herd immunity is needed before that can happen

Even though influenza caused global devastation back in 1918, we don't nowadays regard “the flu” as a deadly disease – although it can still make some people very ill.

One hypothesis that's been doing the rounds since the beginning of the outbreak, is that Covid-19 might become a seasonal occurrence.

A new review, recently published in Frontiers in Published Health, states that Covid-19 might become seasonal in countries with temperate climates, but only when there is herd immunity.

But until then, Covid-19 will continue to circulate across seasons and, in the absence of a vaccine, public health measures such as masks and stringent hand hygiene will need to be applied to contain the virus.

Here to stay

According to Dr Hassan Zaraket, senior study other from the American University of Beirut in Lebanon, Covid-19 is here to stay and will continue to cause outbreaks all year, until herd immunity is achieved.

“The public will need to learn to live with it and continue practising the best prevention measures including wearing of masks, physical distancing, hand hygiene and avoidance of gatherings,” he stated.

Several factors contribute to seasonal viruses

Many respiratory viruses follow seasonal patterns, especially in temperate regions. Influenza and common colds caused by coronaviruses usually peak in winter in temperate regions but can circulate all year long in tropical regions, where rainfall occurs throughout the year.

In their new review, the researchers looked at seasonal viruses and examined the viral and host factors that contribute to their seasonality. They also investigated the latest knowledge on the stability and transmission of the novel coronavirus.

They explained that factors such as indoor crowds, differences in temperature and immunity and human behaviour all influence the way respiratory viruses are transmitted during different times of the year.

However, Covid-19 has a higher transmission rate than flu because of the newness of the disease and the lack of immunity in the population, which means that Covid-19 can’t yet be halted in the summer months. As soon as herd immunity occurs via natural infections and vaccinations, SARS-Cov-2 would become more difficult to spread, turning it into a virus dependent on seasonal factors – as in the case of other coronaviruses such as NL63 and HKU1, which tend to follow a circular pattern like influenza.

"This remains a novel virus, and despite the fast-growing body of science about it, there are still things that are unknown. Whether our predictions hold true or not remains to be seen. But we think it's highly likely, given what we know so far, Covid-19 will eventually become seasonal, like other coronaviruses," said Dr Zaraket.

READ | Is a universal flu vaccine on the horizon?

READ | Is a "twindemic" of Covid-19 and flu coming this autumn? 

READ | By the numbers, Covid-19 "was never like the flu"

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