Arnon Grunberg

Common

Parents

On false positives and false negatives once again – Katherine J. Wu in The Atlantic:

‘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.’

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‘Experts aren’t sure why delayed positives are happening; it’s likely that population immunity, viral mutations, and human behavior all have some role. Regardless, the virus is “acting differently from a symptom perspective for sure,” says Emily Martin, an infectious-disease epidemiologist at the University of Michigan. That’s worth paying attention to. The start of symptoms has always been a bit of a two-step: Is it COVID, or not? If SARS-CoV-2 is re-choreographing its moves, we must too—or risk losing our footing.’

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‘“Once people are vaccinated, though, their immune systems kick in right away,” says Emily Landon, an infectious-disease physician at the University of Chicago. (Prior infection, too, could have an impact.) If the body makes fast work of the invader, some people may never end up testing positive, especially on antigen tests. (PCRs are generally more sensitive.) Others may see positives a few days after symptoms start, as the virus briefly gains a foothold.’

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‘Based on the evidence that’s emerged since, “five days is ridiculous optimism,” said Landon, who recently ran a study showing that a large fraction of people continue to test positive after their fifth isolation day, raising the possibility that they’re still shedding the virus in gobs. Rebecca Ennen, a vaccinated 39-year-old in D.C., didn’t even get her first positive result until Day Six of her illness, as her symptoms were on their way out. “It was just bizarre,” she told me. “I was on the mend.” So Ennen continued cloistering for another five days, until she finally tested negative again. Others, including Gordon and Furmaniuk, have also waited to test out of isolation; it’s what Bhattacharyya “would do too, if it were me.”’

Read the article here.

Five days of quarantine is ridiculous optimism. Good to know.

PCR-test is slightly more reliable than the other tests, we all knew already.

War and a pandemic, the desire for so-called normality and forgetfulness.

Rationality is for machines, people act less than perfect most of the time, so all we can ask is: what kind of risk do we deem acceptable?

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