The new variants of COVID-19, namely BA.4 and BA.5, which are increasingly present in Quebec, take longer to appear positive during rapid tests.
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Are you home and have COVID symptoms? “Take for granted that you are sick and isolate yourself,” said the national director of public health, Dr. Luc Boileau, during his last press briefing on the evolution of the pandemic.
However, more and more people are showing symptoms of COVID, such as fever, fatigue, muscle pain, loss of taste and/or smell, but test negative for several days.
Cold-like symptoms including runny nose and sneezing are also seen.
According to the experts interviewed by CNBC, a mutation in the sub-variants, more specifically the BA.5, would be involved.
"BA.5 and BA.4 cases take a little longer to show up positive with antigen tests for some people," said Esther Babady, chief of clinical microbiology at Memorial Sloan Kettering Cancer Center in New York City.
"When a mutation occurs, it can somehow change the structure of different proteins, which can lead to decreased detection by the antigen test," she explains. It may also be that at the beginning of the BA.4 and BA.5 infection, you do not produce enough SARS-CoV-2 protein.
The expert does not exclude that the brand of the test can also affect the result.
“There are so many rapid antigen tests on the market, and they are not all created equal,” the researcher clarified. Nevertheless, other experts believe that rapid tests are generally very effective.
What if you test negative but you feel sick?
If you are sick and think you have COVID, it is suggested that you isolate yourself and test yourself regularly over several days, said Kevin Dieckhaus, chief of the division of infectious diseases at UConn Health.
Wearing a mask is also recommended even if you test negative but are sick.
It is recommended that you take a test once a day for at least three days, leaving 24 hours between tests.
Mild symptoms for one person can be very serious for another, experts insist.
Public health experts point out that colds, flus and allergies are common now, even though they are found in the winter season.