Rapid tests for COVID-19 are still the best tool for detecting the virus, say experts, even if patients sometimes have to take several tests for a few days before testing positive.
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“It really is the best tool, assures Roxane Borgès Da Silva, of the CIRANO institute, which monitors the COVID-19 epidemic. Rapid tests are very reliable for assessing contagiousness. »
True negative?
Since last January, rapid tests have replaced PCR tests in the general population. However, symptomatic people sometimes doubt a negative result, especially when other family members are positive.
In fact, the rapid test is used to assess the contagious viral load of the patient, but it is not necessarily related to the symptoms. This is why a patient sometimes only gets a positive test after several days of screening, and not always when he feels the sickest.
“There is not a complete relationship between symptoms and contagiousness. This is especially where you have to be careful, ”warns Benoit Barbeau, virologist at the University of Quebec in Montreal.
According to epidemiologist Kevin L’Espérance, the rapid test detects 8 out of 10 cases in symptomatic people, but is less reliable in asymptomatic people (3 to 5 cases out of 10).
According to Barbeau, the many variants of COVID-19, including Omicron (and BA.2), have caused a slight loss in the effectiveness of rapid tests.
“It is not as optimal as at the beginning, but we agree that the reliability remains”, he assures.
The latter adds, however, that after two negative tests, a patient can stop being screened, and remain cautious in his outings.
“You have to limit yourself, there is no point in carrying out excessive tests”, says the virologist.
Return of PCR tests?
Furthermore, these experts do not believe that PCR tests should be made more available to the general population. Even if screening is accessible to people aged 60 and over, few people use it, notes Ms. Borgès Da Silva.
“Nobody goes there, people prefer to stay in the comfort of their homes,” she says. There’s no point in them reopening.”
However, several experts note that these tests were a non-negligible tool, since they made it possible to have precise data on the evolution of the pandemic.
A little advice for the rapid test: the stick must be well inserted in all the routes that can be infected (mouth, throat, nose).