Scientists cautioned against second coronavirus wave in China

Dr Muattar Hanif 02:47 PM, 1 Apr, 2020
For the first time in months, the Chinese province of Hubei, where the coronavirus first emerged, is getting attention for a good reason. COVID-19 cases there have dropped to practically zero, and last week authorities lifted travel restrictions in and out of the province, some 60 days after much of it was dramatically locked down. Now scientists — and the rest of the world — are watching closely to see whether easing the intense measures to keep people apart results in an emergence of new cases. An early analysis suggests that, so far, these fears have not come to pass.

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“It’s time to relax the lockdown, but we need to be alert for a potential second wave of infections,” says Ben Cowling, an epidemiologist at the University of Hong Kong, who will be following the situation in China. If a second wave comes, Cowling would expect to see it emerge by the end of April.

How things unfold in Hubei — and across China — will be relevant to many European nations and some US states that have restricted travel inside their borders, closed most businesses, schools and universities and told people to stay at home, in an attempt to halt the pathogen’s spread. Modelling of the UK outbreak suggests that the country’s social distancing measures, including school and university closures, might be needed for large parts of the next two years to keep the proportion of people with severe COVID-19 infections in hospital at manageable levels.

But if China can show that it can lift its lockdown without a significant re-appearance of COVID-19, it might be possible that such protracted restrictions won’t be necessary.

Extensive testing

Chinese provinces will now use extensive testing and contact tracing to pinpoint new infections, and will maintain some social-distancing practices to prevent a resurgence. The country has also closed its borders to everyone but citizens to prevent cases from being imported. Returning residents will be quarantined for 14 days.

But some researchers say that the situation in China is different because its government acted aggressively, using social-distancing measures to slow down the spread and extensive testing and isolating of infected people to stamp out potential transmission sources. This strategy helped the country contain the outbreak. But other nations, such as Italy and Spain, have focused mainly on slowing the virus — through social distancing — without intensive testing and contact tracing. They will face more challenges when trying to return to life before the pandemic, says Cowling.

And yet, the risk of new outbreaks in China is high given the ease with which the virus passes between people, and the possibility that some infections still linger undetected, says Gabriel Leung, an infectious-disease researcher at the University of Hong Kong. It’s possible that one lockdown might not be enough, and severe efforts to suppress the virus might be needed again, he says. “The tension between health, protecting the economy and emotional well-being will vex every government for the foreseeable future.”

Restrictions ease

Life in Hubei — home to roughly 60 million people — hasn’t returned to normal yet, but people are slowly leaving their homes and returning to work, and factories are reopening. Universities, schools and child-care centres remain closed pending “a scientific assessment of the epidemic control situation”, say government authorities. And travel in and out of the provincial capital, Wuhan, remains restricted until 8 April. Until then, people will need to be tested for the virus to come and go. Since 18 March, there has been only one new case reported in Hubei.

A UK team has modelled whether the increasing movement following the easing of travel restrictions in the six Chinese provinces with the highest number of COVID-19 cases resulted in a surge of new infections. In these provinces — Hubei, Beijing, Guangdong, Henan, Hunan and Zhejiang — the lockdowns helped to reduce new COVID-19 cases to near zero.

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The team, led by infectious-disease researchers Neil Ferguson and Steven Riley at Imperial College London, found that as movement and economic activity in these regions increased in late February for all provinces except Hubei, the number of new infections stayed near zero. As activity restarted in Hubei in March, the numbers of new cases remained low. The analysis concludes that after containing the virus with the severe lockdowns, “China has successfully exited their stringent social-distancing policy to some degree.”

“So far, so good,” says Andrew Tatem, an emerging-disease researcher at the University of Southampton, UK. But the findings must be approached with some caution, he adds. The movement and economic activity levels in the six regions that the group measured were only half of what they were before the outbreak, except in Zhejiang province, where it appears to have matched pre-pandemic levels. There might also be a lag between the increase in activity and reports of new cases. “We’re at the ‘wait and see’ stage. How the graphs look as movement levels keep rising back towards normality will be very interesting,” he says.

Second wave

The virus would have difficulty reestablishing itself in the community if a significant portion of people, between 50% and 70%, were infected and are now immune, says Leung. But he notes that even in Wuhan — which accounted for more than half China’s 81,000 cases — the number of those people infected and are now immune to the disease is probably less than 10% — which means there are lots of people still vulnerable to infection. A vaccine would increase the percentage of immune people, but no vaccines are expected for at least a year. “These numbers don’t allow a sigh of relief,” he says.

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To see the risk of easing these measures, “You only have to look across to Hong Kong to see what’s happened there with a resurgence,” says Tatem. Hong Kong, as well as Singapore and Taiwan, contained the initial spread of the coronavirus with intensive testing and contract tracing.

But over the last week, all three regions have seen a jump in new infections. Most were in travellers from abroad, but some local transmission has been detected. All three regions have now temporarily banned international visitors and are making returning residents undergo a two-week quarantine.

Containment measures should be relaxed “gradually and with ultra-caution and very close monitoring and surveillance”, says Tatem.

Test and trace

China is still implementing extensive COVID-19 monitoring nationwide. Provinces issue all residents a QR code, a type of barcode containing information that is revealed when scanned, based on their health details and travel history. If a person has remained in areas considered safe in China or has been quarantined and tested negative for the disease, they are assigned a ‘green status’ — the lowest risk — which allows them to cross provincial borders, enter hospitals and residential areas, and ride the subway and trains.

The measure not only keeps infected people from mingling with others, but if a new infection is detected, the government can track that person’s movements and pinpoint people they might have come in contact with. Cowling calls this an “advanced form of test and trace” that will allow China to identify as many infected people as possible as quickly as possible, and then isolate them.

The big question is whether that will be enough to stop a new outbreak. Cowling thinks other cities would have trouble if required to do the number of tests that Wuhan did, which at its peak reached about 10,000 tests per day. “There is a danger in focusing too much on testing and isolation,” he says, and adds that social-distancing measures will still be important.

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Chinese cities seem to fear the dangers of loosening measures to keep people apart too soon. Museums and attractions in Shanghai, which have been open for the past 18 days, were shut again from today. Cinemas were also closed again. Although the city has relaxed some rules: people are no longer required to have a pass to leave residential compounds, and delivery people are able to enter these areas. The city also dropped the requirement to wear masks in some public areas — a practice police had previously enforced with drones or robots.

Most of the countries now facing raging outbreaks, including Italy, Spain and the United States, are relying on social-distancing policies and getting people to stay home. China implemented those measures, but it also built new hospitals and conducted extensive testing. Then, officials went door to door to check people’s temperatures. They tested anyone with a fever, and isolated positive cases. “The extra work allowed them to stop the virus,” says Cowling. “People are following China, but not in exactly the same way,” he says.

-Courtesy by Nature