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Coronavirus: How China plans to test every person in Wuhan Coronavirus: China's plan to test everyone in Wuhan
(5 days later)
China is undertaking an ambitious plan to test the entire population of Wuhan, the city where the Covid-19 pandemic began, following the emergence of a cluster of new infections. China has been carrying out an ambitious plan to test everyone in Wuhan, the city where the Covid-19 pandemic began, following the emergence of a cluster of new infections.
The authorities had originally promised to test all 11 million people in 10 days. The authorities had pledged to test the city's inhabitants over a 10-day period, starting on 14 May.
But it now appears they might be aiming for a less ambitious timetable. We've looked at what was achieved, and over what period of time.
What's the scale of the task? What was the target?
Before this latest mass testing campaign began, there were about 60 centres across the city, with an overall maximum capacity of 100,000 tests a day, according to the official Hubei Daily newspaper. Wuhan has an estimated population of 11 million people.
So that testing capacity would have needed to be substantially increased to reach the entire population in just 10 days. But those already tested in the seven days prior to mass testing starting in their district, as well as any children under six years of age, have been excluded.
Subsequent statements from the authorities have acknowledged the testing period will take longer, with different districts within the city carrying out testing over staggered 10-day periods. The total number may have been reduced further given that some residents who left Wuhan before the lockdown in January may well not have returned.
"Each district finishes its tests within 10 days from the date it started them," the Wuhan Centre for Disease Control said. The authorities said they would begin with people considered most at risk - such as those in more densely populated areas as well as those in key jobs such as healthcare.
It's not clear what the exact timetable is, but on 18 May, all 13 districts in the city were carrying out tests so the whole operation should be over by 28 May at the latest. We then need to consider the timeframe, which has shifted somewhat since the initial announcement.
And as of 20 May, the Wuhan Health Commission said more than 2.8m tests had been completed. The Wuhan authorities later suggested different districts within the city would be starting at different times.
Chinese state media has reported that some testing centres in Wuhan are now using a method called batch testing. "Each district finishes its tests within 10 days from the date it started them," the Wuhan Centre for Disease Control said, which effectively extended the deadline beyond the original pledge.
This means grouping individual test samples together so as to speed up the whole process. It still remains a very ambitious plan, so do we know how close they've come to achieving their goal?
They would only carry out individual tests if a positive result comes up in the batch. How many have been tested?
How many people will be tested? All the data we have comes from the local health authorities in Wuhan, so we need to be aware of not having independent verification for the numbers.
The population of the city - originally 11 million - has fluctuated in recent months. But let's start with Wuhan's testing capacity before this latest mass campaign.
The authorities said up to five million people had left the city for the lunar New Year holiday before it was locked down on 23 January. There were about 60 centres across the city, with an overall maximum capacity of 100,000 tests a day, according to the official Hubei Daily newspaper.
The lockdown then lasted until 8 April, but it is unclear how many of these residents have returned. That would have made it impossible to reach everyone in Wuhan over 10 days. So testing capacity would have needed to be significantly boosted to meet the challenge.
One recent estimate by a leading Chinese science journal (Zhishi Fenzi) said that eight million people needed to be tested in Wuhan. One way to scale up testing is to use a batch testing method. Chinese state media have reported that this has been used in Wuhan.
They arrived at that figure by excluding anyone who had been tested in the seven days prior to mass testing starting in their district, as well as all children under six years of age. This process groups individual test samples together to speed up the whole process.
Should everyone be tested? Reports suggest they have been using batches of between five and 10 samples in Wuhan, only carrying out individual tests if a batch proves positive.
The authorities have said they will begin with people considered most at risk - for example in the older, more densely populated areas, as well as those in key jobs such as healthcare. This would be an efficient way to test large numbers of people where infection levels are low, as most batches would produce negative results.
And as we've seen, those tested recently won't need to be tested again. So far, the authorities say they have found just over 200 positive cases out of all the tests done so far.
But Chinese Center for Disease Control and Prevention chief epidemiologist Wu Zunyou told state TV: "The virus could take longer to manifest itself in patients with weak immunity and these people are also prone to 'on' and 'off' symptoms." Even with this batch testing in place, processing capacity would have needed to be scaled up massively.
Wuhan University's Yang Zhanqiu said there was no need to test everyone living in neighbourhoods with no reported cases. Health officials in Wuhan say they carried out 1.47m tests on a single day, 22 May - so a huge increase from the 100,000 a day prior to this testing campaign starting.
But he also warns: "You'll never know if people become infected after testing negative." In total, according to the Hubei health commission website, nine million test samples had been taken by 24 May - 10 days after the campaign started.
And US-based Council on Foreign Relations senior fellow for global health Huang Yanzhong said: “There would still be the possibility of isolated outbreaks in the future, which even large-scale testing will not address." Of these, the commission says 6.57 million had been processed.
Additional reporting and research by Yitsing Wang, in Beijing, and Pablo Uchoa and Wanyuan Song, in London. That's a very large number and although it's not possible to verify independently, it appears that Wuhan has managed to ramp up its testing to reach a high proportion of its population during the 10 day period.
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