Covid-19: Is France doing too many tests?
Experts have cast doubt on whether the French government’s mass testing strategy is the most effective way to fight Covid-19, as the country completes upwards of one million tests per week.
What is the current testing situation in France?
For months, the French government has hailed the importance of mass testing for Covid-19, and health minister Oliver Véran has long said his aim is to exceed one million tests per week.
This milestone has now been reached.
However massive increases in testing have meant that laboratories have been overrun, and there have been reports of long queues and waits for walk-in tests and advance online appointments.
Mr Véran has acknowledged the delays, but said that 80% of test results are being returned within 36 hours at most, and that testing - coupled with immediate self-isolation and treatment for those who test positive - is a key way to stop the virus from spreading.
The tests concerned are PCR (polymerase chain reaction tests), which tell whether a patient has the virus at the time of testing, rather than blood tests, which only show antibodies in the weeks following infection.
Overall, experts have suggested that mass testing alone is not enough to stop the virus from spreading, and that such a policy must be coupled with the correct testing time, and self-isolation strategies to be effective.
So is mass testing the best policy?
In an analysis by newspaper Le Figaro, Dr Lionel Barrand, president of young biologists union le Syndicat National des Jeunes Biologistes Médicaux said that he did not necessarily agree with the government's strategy, and suggested that more “targeted” testing would be more effective.
He said: “Either we test everyone, or we target. With a population of 70 million people in France, testing everyone to a tune of one million tests per week would take 70 weeks, so more than a year. An impossible task, and no country has made such a decision.”
So what would ‘targeted testing’ look like?
Dr Barrand said that targeted testing would prioritise the most at-risk people, and also those who are returning to the country from being in a high-risk zone, for example. He also said that the timing of tests is very important, and that this should be taken into consideration in any testing strategy.
He explained: “We must take into account that a test can be negative one day, because the person is in the incubation period, and then positive the next day. The period in which a PCR test is positive lasts about a week, in a highly-infectious phase. So this is not a tenable strategy.
“We must therefore target high-risk people, and test them at the right moment, to avoid false negatives. In the first instance, we must offer tests to people who have symptoms. And get their results quickly.
“Then, we must test people who are in contact with positive people. But we must allow seven days after contact to avoid false negatives. That is how we will break the spread. Testing some asymptomatic people is also a good idea, such as travellers coming back from countries where the pandemic is raging.”
A study researcher Nick Grassley, at Imperial College London, also appears to argue for a targeted test-and-isolate strategy.
Professor Lepelletier head of bacteriology at the CHU hospital in Nantes, and a member of health council le Haut Conseil de la Santé Publique, explained that the study showed that “testing the majority of the population reduces the risk of a spread by 2%, but when we isolate symptomatic people at home, as well as their families, when coupled with targeted testing with fast results, and immediate calling of contacts who must then isolate as well, the effectiveness rises to 64%”.
So testing alone is not enough?
Experts suggest that testing must be coupled with proper self-isolation of the infected person and their contacts, to be effective.
Professor Didier Lepelletier emphasised that testing alone is not enough to stop the spread, it must be coupled with the message to self-isolate and keep up social distancing.
He said: “This policy of ‘testing, testing, testing’ is less important than the targeted testing of symptomatic people, and ‘isolate, isolate, isolate’.
“It is important that symptomatic people self-isolate and get tested quickly, as should their contacts, in a bid to stop the beginning of a cluster [local outbreak].”
Is the government’s ‘test, test, test’ policy purely political?
Dr Barrand has also suggested that the government was keen to step up testing efforts in a bid to make up for what some saw as lost time when the epidemic first broke out in March.
He said: “We do blame the government [for the test backlog], as we warned them about it. But they no doubt had a complex about it due to [what happened in] March.”
“[But] if we do not test the right people, then testing is counter-productive. Searching to reach big numbers for the sake of it is simply a “symbol”, but puts pressure on staff, tests, and the availability of machines.”
It has also been noted that the government appeared to decide on its “mass testing” strategy without consulting with le Haut Conseil de la Santé Publique, which is unusual for a national health policy.
Dr Barrand used the example of the department of Mayenne, which asked everyone to get tested after it saw a spike in cases. He said: “Response times in laboratories exploded, even for symptomatic people who needed a quick result to break the chain of transmission of the virus.”
He concluded: “Without drastic measures by authorities to limit gathering, and good actions from the population, the virus will be spread even more quickly, due to this non-targeted testing strategy.”
According to one anonymous member of health agency l’Agence Régionale de Santé, setting the goal at one million tests per week allows the government to “reassure the population” but is not effective alone.