Tests also differ in their sensitivity, and people differ in how they perform them. “Some people get a swab test and it’s like they barely touch their noses,” Dr. Gordon said. “While with other people, in fact, with a family member recently, I had to say, ‘Don’t hurt yourself,’ because they were really going in there.”
What to do
One lesson is that prolonged positive results are common enough that people who leave isolation before day 10 should continue to take precautions, such as wearing a proper mask, experts said.
Beyond that, scientists disagreed. Some have recommended that people be isolated until the test is negative for the antigen, even if it takes more than 10 days.
“We can now tailor the recommendations to individual experiences using the results of the quick tests to guide us,” said Dr. Grad. “And since we know that some people can have extended courses, I think it’s reasonable that if you can continue to isolate if it’s positive, you should.”
But several others said that as a matter of public health policy, it makes no sense to ask most healthy people to isolate themselves, or even continue testing, for more than 10 days.
“No one says there are no people, perhaps statistically speaking at the end of the queue, who can transmit after day 10,” Dr. Chin-Hong. But it is likely that people in this stage of the infection will not play a major role in the spread of the virus, and continued testing could keep many people out of work or school without much benefit to public health. to say. “And also raise an issue of fairness,” he added, “such as, ‘Who the hell can have enough evidence?'”
However, experts say there are some circumstances in which people should continue to be tested and potentially isolate themselves beyond day 10. These include people whose symptoms do not improve and those who are immunocompromised. which can eliminate the infectious virus for longer periods of time. (The CDC recommends that people with weakened immune systems be isolated for up to 20 days).