In early May, 27-year-old Hayley Furmaniuk felt tired and a bit congested, but after rapid-testing negative for the coronavirus two days in a row, she dined indoors with friends. The next morning, her symptoms worsened. Knowing her parents were driving in for Mother’s Day, she tested again—and saw a very bright positive. Which meant three not-so-great things: She needed to cancel with her parents; she had likely exposed her friends; a test had apparently taken three days to register what her vaccinated body had already figured out.
Tests are not and never have been perfect, but since around the rise of Omicron, the problem of delayed positivity has gained some prominence. In recent months, many people have logged strings of negatives—three, four, even five or more days in a row—early in their COVID-symptom course. “I think it’s become more common,” says Amesh Adalja, an infectious-disease physician at the Johns Hopkins Center for Health Security.
No one can yet say how common these early negatives are, or who’s most at risk. But if SARS-CoV-2 is rewriting the early-infection playbook, “that makes it really scary,” says Susan Butler-Wu, a clinical microbiologist at USC’s Keck School of Medicine. “You can’t test and get a negative and actually know you’re negative.” Misleading negatives could hasten the spread of the virus; they could delay treatments premised on a positive test result. They also buck the current COVID dogma: Test as soon as you feel sick. The few days around the start of symptoms are supposed to be when the virus inside you is most detectable and transmissible; we built an entire edifice of testing and isolation on that foundation.
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