Studies attempting to assess how many asymptomatic infections account for long COVID symptoms have varied. … [A] study, which is under peer review, used data from the University of California’s electronic health records and estimated that number could be as high as 32 percent. Melissa Pinto, a co-author of the latter study and associate professor in the Sue & Bill Gross School of Nursing at University of California Irvine, says the researchers examined healthcare records of people who tested positive for COVID-19 but hadn’t reported symptoms at the time of infection—only to come in later with symptoms associated with long COVID-19.
Why some COVID-19 infections may be free of symptoms but not free of harm
National Geographic, Sept. 1, 2021
September 1, 2021