Scale of Covid-19 contagion may be more serious than we think

SINGAPORE: For every person with coronavirus disease 2019 (Covid-19), it seems that at least three or four others are going to be infected too.

That is how contagious the new coronavirus is — and that is a “very conservative” estimate, said Dr Asok Kurup, chairman of the Chapter of Infectious Disease Physicians, Academy of Medicine, Singapore. “The numbers are likely to be much more exponential.”

The outbreak may seem similar to the severe acute respiratory syndrome (Sars) epidemic in 2002-03, but it is becoming apparent to infectious disease specialists like him and Dr Leong Hoe Nam how the new coronavirus is different.

“(By) coming close or talking, you may spread the infection, not like Sars,” said Dr Leong, who practises at Mount Elizabeth Novena Specialist Centre.

WATCH: Just how contagious is Covid-19? (5:47)

In fact, Covid-19’s transmission mechanism is “closer to H1N1 or influenza” than Sars, Minister Lawrence Wong, co-chair of the Multi-Ministry Taskforce on Covid-19, said yesterday.

“Like influenza, (our researchers) have found that Covid-19 is infectious when the symptoms are mild. Because of this … it’s also the case that Covid-19, like influenza, can spread quite quickly.”

This ease of spread means not only that the virus is harder to contain than Sars, but also that the current scale of contagion could be more serious than thought, the programme Insight finds out. (Watch the episode here.)

‘UNPRECEDENTED SPREAD’

The Sars virus infected more than 8,000 people and killed 774 worldwide over nine months, but the novel coronavirus has infected more than 63,000 people — with over 1,300 dead — in barely two months.

WATCH: Covid-19 closer to H1N1 than Sars in terms of transmission: Lawrence Wong (5:24)

The thing is, the incubation period — the time between exposure and the onset of symptoms — is typically two to seven days for Sars patients.

And they are most likely to be contagious only when they have symptoms, such as fever or cough. “Infection … happens best in the second half of the illness, after the first seven days,” said Dr Leong.

But the novel coronavirus could possibly be spread by asymptomatic individuals, that is, those who are not showing signs of being ill. This means these people could be spreading the virus undetected, before the onset of illness.

“This allows the virus to propagate very quickly, across large swathes of area (with) many, many people. Hence we’re seeing these numbers … of infections,” said Dr Leong, who called it an “unprecedented spread”.

READ: Hubei reports nearly 15,000 new COVID-19 cases with new method of diagnosis

READ: Coronavirus outbreak ‘just beginning’ outside China, says expert

The patients whom doctors end up seeing and treating, however, are the sickest “10, 20 per cent”, he reckons.

The bulk who are asymptomatic or have minor symptoms that can be taken for, say, the common cold might be “(four) times more than (the patients) we’re seeing now”, he warned. “They’re active propagators of the virus.”

Another problem complicating global efforts to contain the virus is international travel. While there are flight suspensions and restrictions in place on travel to and from China, these may not be enough to contain the spread of infection.

“Even if you say, let’s not get people coming in from China … (there are) many people who are already affected outside of China. And these people are still travelling,” pointed out Dr Kurup. “So we’re still vulnerable.”

This means many of the asymptomatic people round the world may be travelling, and transmission is a possibility. “Now, how infectious and how transmissible they are, we don’t know,” he said.

HEARTLESS IN HUBEI?

While the number of coronavirus cases in China may be stabilising, this apparent slowdown in the epidemic’s spread should be viewed with “extreme caution”, World Health Organisation director-general Tedros Ghebreyesus said recently. “This outbreak could still go in any direction.”

To try to halt the spread of the virus, the Chinese authorities have resorted to measures like placing Wuhan city — with a population of 11 million — on lockdown, closing roads to the city and shutting down its public transport.

“The fact that the Chinese government officials did it tells me they were desperate,” said Dr Leong.

It also told him many people were falling sick rapidly, “they were going to get out of Wuhan for the Chinese New Year festivities, and from there, the spread would’ve been even (more) unprecedented”.

“It seems very heartless, it seems unimaginable, but (the lockdown) was the right thing to do,” he added.

The city’s being sacrificed for the good of this nation and for the … world.

The lockdown was later expanded to other cities in Hubei, a province with nearly 60 million people. And even as efforts to contain the spread of the virus go into full swing, it remains unclear if the peak is near.

“If there’s a best-case scenario, it could potentially lead to a drop in numbers. But I haven’t seen that … We’re still seeing the cases (going) up and the mortality (too),” said Dr Kurup.

“Until and unless we see that number’s (being) mitigated, we can’t predict what’s going to happen in the region. So this is going to go on for a while.”

Watch the episode here. The programme Insight is telecast on Thursdays at 9pm.