After the deconfinement, massive screenings to avoid the rebound of the epidemic?

CORONAVIRUS – Don’t get overwhelmed again. In Le Havre, a new device has just been launched, in the hope of better preventing the Covid-19 epidemic. From Monday December 14 until Saturday December 19, all the inhabitants of the agglomeration can (if they wish) be tested in schools, large companies or in car parks transformed into laboratories especially for the occasion.

These massive screenings come after the restrictive health measures and the bulk of the second wave of the coronavirus. Too late to be of use? No. This very large-scale testing campaign is not intended to stem the epidemic tidal wave but it could, on the other hand, prove to be complementary to the tools to combat Covid-19 at low tide, to avoid and stop deadly local runaway beginnings.

If this device tested in Havre under the aegis of ARS Normandy but also in Lille-Roubaix, Saint-Étienne and in the Ardennes go well, massive screenings could happen in other French cities, under certain conditions.

The mayor of Le Havre Édouard Philippe said he was happy if 50% of the inhabitants were going to be tested, although he doubted such enthusiasm. On an on-site visit this Monday, Olivier Véran recalled that these screenings are not compulsory: “We do not have in France the obligation to be tested (…) it is not possible in France, but we encourage it, ”he said.

Large-scale experimentation

With this experiment, the government wants to see if such an operation works from a logistical point of view. “These operations are as much a means of limiting the spread of the virus in the communities concerned, as a lever for testing our strategy,” explained the Minister of Health.

Never in France has an operation of this magnitude been carried out. It is therefore necessary to ensure each time that there are sufficient tests and personnel, places to welcome the public. The government also wants to verify that the results are available quickly and that the public is well informed if it is positive.

Many asymptomatic people are at risk of finding out that they are sick. The ARS will then offer to immediately identify the person’s risky contacts and then detail the advice to isolate themselves effectively. Health authorities recommend that they stay at home, even if they are well, so as not to circulate the virus, perhaps waiting to be tested positive. But if massive tests are being put in place today, it is precisely because the numbers have fallen in recent weeks.

Useless when the virus is circulating fast

During epidemic tidal waves, massive screenings are indeed unnecessary. Above a certain number of patients per day, the virus circulates so fast that it is humanly not possible to identify the contact cases and to isolate all the patients. There are so many contacts and new cases that we can no longer follow. “Despite our numerous tests carried out in the United States, the virus has largely overwhelmed these efforts” explained Dr. Jennifer Nuzzo, an academic from the Johns Hopkins Health Security Center, a reference across the Atlantic in the fight against epidemics.

However, the advantage of screening in general is precisely when it is then possible to trace contact cases and isolate patients. People with severe forms of Covid-19 develop very characteristic, easily identifiable symptoms. This is of course not the case with asymptomatic patients: testing everyone is then a means of combating the evolution of the epidemic when it is associated with tracing contact cases and isolating patients.

This is also what indicates preliminary results of a study conducted in particular by Harvard University, pending review before publication. The operations which are about to be launched in France are therefore full-scale experiments to check whether it is possible, when the virus is not yet circulating intensely in a territory, to trace and isolate effectively.

In fact, mass screening is especially useful at “low tide”, when the virus does not circulate widely across a country. “Mass screening can be used for operations to eliminate the circulation of the virus when it is very low” details the Scientific Council, in its opinion of 14 November. Such operations have been carried out in several Chinese cities for example. From the first cases, millions of tests were carried out in a few days, to cut off any return of Covid-19.

The memory of Marseille in everyone’s mind

But beware, the exercise is not without gray areas. The Scientific Council has regularly alerted to the difficulties posed by such screening. Beyond the effort and the cost, it is rare that exercise is truly 100% effective. People who test negative can test positive over the next few days if they are tested too soon after coming into contact with the virus.

At the scale of an agglomeration or a country, massive screening is therefore not a very reliable means of monitoring the epidemic. The goal is to overcome localized clusters, by delivering an immediate photo of a locality. This table, added to the tracing and distancing measures, can then prove to be effective against a new generalized outbreak.

Like several Chinese cities, it would be a question of nipping in the bud any possible local epidemic runaway. In September 2020, while the coronavirus was circulating little nationwide, cities like Marseille or Bordeaux saw their contamination rates explode in a few weeks. Massive screening could be used in similar cases, to identify and isolate patients and thus avoid a national epidemic resumption or very restrictive health measures.

Thus, if the current operations are successful, massive screenings could happen in other cities in France, when the country has deconfined. “It is on the basis of massive screening that we could be led to increase our surveillance, once the confinement is lifted” indicated the Minister of Health. It would then be a new tool to stem epidemic resumptions, at the local level, in addition to barrier gestures, health measures and vaccination.

See also on The HuffPost: For the decoration of the Christmas tree in 2020, they replace the balls with masks

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