Reminder: Respiratory Viruses Infect Huge Numbers of People all The Time, and Nobody Cared About This Until 2020

Perspective from a 2018 New York study that tested a bunch of healthy adults for common respiratory viruses. Over 6% tested positive.

The ever-sharp Zacki on Twitter points to this intriguing 2018 study out of New York. The authors administered PCR tests to 2,685 people at a tourist attraction in New York City, between the months of January and July. Over 6% tested positive for one of seven common human respiratory viruses. In the winter, human coronaviruses were the most common; in the summer, rhinoviruses took the lead. By design, the study targeted healthy populations, and so we must imagine that it substantially understates the true rate of virus infection.

The authors don’t find a significant difference in the overall prevalence of positivity between winter and summer. In their small sample, it’s only the mix of viruses that changes. This is another piece of evidence in favour of my crazy theory, that a great part – perhaps a majority – of spring and summer allergies are in fact persistent low-grade rhinovirus infections.

Other studies, particularly on rhinovirus, find even larger incidences of infection. There is this paper, which looks at rhinovirus in infants and finds that 20% of their sample are asymptomatic positives; or this case-control study of all ages, which finds rhinovirus in 17% of their asymptomatic controls.

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