There are now so few cases of coronavirus in China that on certain days, the authorities see no local transmission. China has gone from reporting thousands of cases a day in February to one or two a day now. In the past week, officials from the National Health Commission of China have reported only 5 new domestic cases. The total number of new cases was higher, but almost all were imported cases from travelers recently returned from abroad.
China has reduced the transmission of coronaviruses to almost zero (although international academics question the notification of cases in China and the fact that some cases are forgotten, it is generally believed that they have suppressed transmission to a very low level). But some undetected cases are probably still floating around, and the virus can still be brought from abroad.
Life has not yet returned to normal. Many restrictions from the health crisis are still in place. Isolation rooms are always open to patients, even with mild symptoms. Quarantine centers house suspect patients and contacts of confirmed patients. The test laboratories are still operating. And surveillance systems are always on alert for new cases.
“We are very aware that there could still be a second wave in China. You can, “said Kylie Ainslie, research associate at the MRC Center for Global Infectious Disease Analysis at Imperial College London.
“However, we have not yet seen this happen. “
Ainslie and his colleagues have looked at how China is emerging from one of the greatest blockages in human history. They analyzed GPS tracking data from human movements to monitor how social restrictions are relaxed or tightened in a given area.
“The areas where the epidemic has been less have had their movement restrictions removed earlier,” she said. “But that didn’t mean completely. It meant first that they started big factories and started letting the people who work there go back to work so they can restart their industries. “
Movement restrictions – essentially orders to keep people at home – are still in place in some areas and some people are considered to be at high risk.
Most factories in Wuhan, which were the epicenter of the epidemic, for example, have not yet started their production chains.
“One of the things that China does is that it relaxes social distancing measures, but does not remove them completely,” said Ainslie. “And that doesn’t delete them at random.” “
For example, schools in much of the country remain closed.
In several provinces where reported cases have fallen to zero or close to zero for some time, they have seen the number of cases rebound. But the increases were mainly caused by travelers arriving from Europe.
According to Ben Cowling, an epidemiologist at the University of Hong Kong, these “imported” cases are much easier to contain and do not pose as much of a threat of wider transmission.
“There is less opportunity for infections to enter the general community of these travelers because they (travelers) are so closely watched,” said Cowling. Anyone arriving in China must now follow 14 days of quarantine where the authorities can closely monitor their health. “So if they turn out to be infected, which is a small minority, they are isolated. Their contacts are found and quarantined. And that will slow down any leak in the community at large. “
Cowling says public health officials in China and elsewhere have two sets of tools to contain the epidemic: social distancing and case management. Social distancing makes it more difficult for the virus to find new people to infect. Case management individually searches for cases and potential cases, then isolates them – as well as the virus. China used these two tools aggressively.
“With a large testing capacity, they were able to quickly reduce the number of infections,” said Cowling. “I think that faster than we will see the number of cases decrease in New York or in the north of Italy or in Spain or in France. And that’s because in China, the lock was a more extreme version of a lock. It was a total lockdown. “
People were ordered to stay at home and they were prohibited from traveling.
“In addition to the lockout, there was also heavy use of testing, isolation and quarantine,” said Cowling. “So all of these measures are like, really, really trying very hard to bring the numbers down. “
China is now in a “crackdown” phase of the epidemic. Transmission has almost dropped to zero, but some undetected cases are probably still floating and the virus can still be brought from abroad.
To ensure that no other major epidemic occurs, China is experimenting to see how far it can alleviate very restrictive social distancing while keeping its test and quarantine apparatus operational.
“We will see in a month or two if it is possible to return to a relatively normal social mix and be able to simply rely on test tests, monitoring, isolation, quarantine” to keep the virus at a level extremely low in China, he says.
As China now tries to find a way to release social distance without letting the virus re-emerge, it is also an issue that European countries and the United States hope to address in the coming weeks. But the United States may have a harder time doing this than China. Cowling says that one problem facing the United States is that there are many different epidemics that are managed primarily at the state level and can peak at different times.
“It is possible that New York is coming out of its place of closure, having reached a low level. But there are other cities where they have a lot more infections and it’s going to be very difficult to have travel restrictions, “Cowling said. “And the worst case is that infections are rebounding in the United States. So the lock is released, then the infections come back, then you have to close the lock and no one wants that to happen. So this really is an urgent matter of how best to suppress transmission across the United States ”
Watching how China is navigating this phase of suppression may offer insights to the United States and the rest of the world.