At what point is the Wuhan mass test for coronavirus


In less than two weeks in Wuhan – the Chinese city from which the pandemic started – over 6.5 million swabs were carried out on the population, as part of a large mass test announced in mid-May to evaluate the spread of coronavirus and the new infections. For comparison, 3.6 million tampons have been made throughout Italy since the beginning of the epidemic: and Italy has about six times the inhabitants of Wuhan. The management of the Chinese initiative has involved a gigantic logistical activity and the expense of the equivalent of hundreds of millions of euros, but not all experts agree on its usefulness to reduce the risk of new infections.

For days in the Wuhan neighborhoods – a city of about 11 million inhabitants – thousands of workers and health workers have been working tirelessly to collect saliva and mucus samples from the inhabitants, using swabs then sent to dozens of laboratories for analysis. Withdrawals are carried out in temporary centers organized for the occasion, on the workplace and at home, for people with mobility problems.

The Wuhan administration had decided to start the mass test after detecting less than ten new coronavirus positive cases, after more than a month in which no new infected had been detected. The initiative was then organized in a very short time, with the aim of better addressing the problem compared to the first months of the year, when the epidemic had spread to a large part of the city, and to demonstrate to the population the will of the government.

The entire operation was funded by the Chinese government, which invested a lot of money to upgrade the labs and the ability to process large quantities of swabs every day in the areas of China most at risk. The daily analysis capacity has reached 1.7 million swabs, a huge step forward considering that just in Wuhan until recently, just over 46,000 swabs were processed every day.

Wuhan, China (Chinatopix Via AP)

Mass testing has so far involved around 90 percent of the population to be tested. Swabs will not be necessary for all inhabitants, because many of them had already performed a test in the last few weeks. Last Tuesday, about ten days after the launch of the initiative, the health authorities announced that they had detected only 200 positive cases, out of the millions of swabs performed. The positives were mostly people who showed no symptoms and who could therefore have infected others.

As had become evident in the most intense phase of the health emergency, the government of China imposes incisive and categorical choices on the population, which could hardly be proposed in the West. In the case of mass tests, the workers scoured the neighborhoods from house to house to induce the inhabitants to undergo the test at the closest sampling point.

In some neighborhoods the incentives have been quite threatening. The operators reminded the residents that by avoiding the test they would have risked a downgrade of their health profile, which is used by the government to evaluate who and how it can receive particular health treatments or move freely during the pandemic. For example, they signaled the risk of receiving bans for entry to supermarkets or banks, and the possibility of being subjected to further restrictions.

Participation in the complex was high, with hundreds of thousands of inhabitants queuing at the collection centers. In the most densely populated areas, a system was used to reserve one’s seat in the queue, reducing waiting times. However, many people had to wait for their turn in line in the sun, on particularly hot days with highs around 32 ° C.

Wuhan, China (Chinatopix Via AP)

Aware of the risk of contagion for people in the queue, the organizers have set up most of the outdoor collection centers, asking the population to wear a mask and to keep a safe distance from others. The access points were also kept under surveillance, with staff to measure each participant’s body temperature. Healthcare professionals were asked to replace or disinfect the gloves after each swab, to reduce the risk of passing on the coronavirus.

Despite the precautions, some inhabitants have reported chaotic situations, with hundreds of people in line and without the possibility of practicing physical distancing adequately.

To speed up the analysis, Wuhan has been followed an approach already adopted previously and in other countries: analyze multiple swabs at once. The procedure involves putting together the samples taken by a group of people and having them analyzed as if it were a single sample, in order to shorten the times. If the specimen proves positive, people whose swabs had been combined together are contacted, performing a new test to check who is positive. This procedure can be useful in circumstances where the incidence of positive cases is quite low and many samples have to be processed.

While acknowledging the unprecedented effort conducted in Wuhan, numerous experts have raised doubts about the usefulness of a mass test to keep the spread of the epidemic under control. The analysis of a representative sample of the population, made up of about 100 thousand people, would have been sufficient to verify in which neighborhoods the coronavirus was still widespread to the point of further investigation.

Doubts were also raised about the accuracy of the tests, given the need to make so many in no time. The errors during the samples and during the analyzes could have led to the detection of fewer cases than the real ones, partly conditioning the results. In recent weeks, some doubts have also surfaced about the quality of the reagents and other products used to analyze the samples, especially from countries outside China and that have relied on Chinese companies to obtain the diagnostic material.

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