From best to worst case, here’s how coronavirus could play out

CHARLY TRIBALLEAU/AFP via Getty Images

Thousands dead. Infections in 25 countries. Reports of coverups and missing journalists. Panic seems a reasonable response to the deadly novel coronavirus that emerged from Wuhan, but there’s a chance it ends with a whimper, not a bang – fading into obscurity like Sars.

There’s no question that coronavirus, or Covid-19 as it’s now been named, is a serious threat. In January, the World Health Organisation declared it a public health emergency of international concern, which has only happened five times before. At last count, there have been 44,653 confirmed infections of Covid-19, with 1,113 deaths.

Terrible though that is, there’s a silver lining: the daily taly of new cases is at the lowest level since January, suggesting the rate of infection may be slowing, according to Chinese officials. “The past week the epidemic within China seems to be on the decline by about half the number of new cases in a day from a week ago,” says Paul Hunter, a professor in medicine at the University of East Anglia. “I would, however, caution against an over optimistic interpretation of that as history has a lot of outbreaks that people relaxed when people thought they had it under control only for it to comeback stronger.”

Previous viruses, Sars included, suggest what could be next for Covid-19. There’s three main scenarios: the virus could spread into a global pandemic, it could remain largely contained within China and taper off on its own, or it could become another illness that never leaves us, flaring up seasonally as the flu does now.

Right now, there’s no question Covid-19 is an epidemic. “We’re in containment phase at the moment,” says Bharat Pankhania, public health lecturer at the University of Exeter. “We’re trying to hold back a dam that is leaking and we’re trying to stop it from bursting.” There are infections outside China – the next-hardest hit country is Japan with 203 cases (including those aboard the Diamond Princess) – but Jones says those are “satellite outbreaks”, and that so far the “true pandemic seems to be on hold.”

If that dam does burst, we’re looking at the potential for a global pandemic. That requires existing containment to fail and for the virus to spread elsewhere – and we haven’t had that yet. “For a pandemic we would need to see sustained person-to-person transmission across multiple counties in more than one region,” says Hunter. “There does seem to be a gradual increase in cases outside of China but as yet no evidence of sustained person-to-person spread – but still early days. So a pandemic is still possible but not inevitable. A lot will depend on how effectively cases are managed in countries outside of China.”

A global pandemic is the worse-case scenario, but even if the spread of Covid-19 is controlled in some countries, others could be harder hit. There are already suggestions that North Korea is facing an epidemic of its own, with its weak healthcare unable to cope. If Covid-19 spreads to a country with a less robust healthcare system or disorganised government – and there are plenty of both around the world – there’s the potential for disaster. “[We] wait to see what will happen when it gains a hold in a populous, resource poor, region,” says Ian Jones, professor of virology at the University of Reading, although he adds that hotter, drier climates may help reduce transmission.

There are other ways nature could help, suggesting the potential for a less horrific scenario. The key point here is that mutations don’t tend to make viruses worse, with a study of Sars suggesting it actually reduced its ability to spread. “Natural history shows they lose their potency,” says Pankhania, saying that’s why swine flu came and went; Sars hasn’t been spotted since 2005. “I hope this coronavirus will behave in the same way – most of them operate like this.”

Hunter notes that previous experience with Sars and other droplet-spread diseases shows it’s possible that the virus’ spread will simply decline before dying out in the summer – again, because of warmer, drier weather reducing the spread. “My best guess is the outbreak will continue for a few more months yet before disappearing during the summer,” Hunter says. “Whether it resurfaces next winter is uncertain.”

That doesn’t mean the work being put into containment is a waste – it’s exactly the opposite. By containing it, we prevent infections and deaths while the virus evolves into something less virulent or comes up against summer weather that slows its spread. “We need to keep it at bay for as long as possible,” says Pankhania. “I expect it to peter out. That is my big hope. If it doesn’t, we have a problem.”

If Covid-19 doesn’t die out on its own, it may become endemic. An endemic virus is one that never disappears, flaring up now and then, such as the flu. Jones believes that’s what we should expect with Covid-19. “The most likely endpoint I think is that the virus will become the fifth human coronavirus and will cause regular, probably seasonal, outbreaks,” Jones says. “The level of these will depend on the level of immunity in the population which in turn will depend on a vaccine appearing within a reasonable time frame and the at-risk population taking it up.”

That raises the spectre of regular coronavirus breakouts, particularly problematic given the high rates of infection and death, but we have the ability to fight back with vaccines. However, as with the previous scenario, we need to buy time via containment, as developing a vaccine takes months or years.

There’s no way to know which road COVID-19 will follow — be it global pandemic, evolving itself out of existence, or becoming an endemic threat — and there’s plenty else we don’t know about the virus. Pankhania notes that we have figures for rate of infection and fatalities, but they may not be accurate. The incubation period is assumed to be two weeks, becoming infectious when symptoms show, but confirmation is needed. And given the bulk of cases remain in China, we need that country to be open.

“More data flowing is needed to understand it better,” Pankhania says. And we’ll get more infections to study, he says, because regardless of what happens next with Covid-19, right now we remain in the epidemic stage. “Expect more cases,” he says.

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