This isn't a study, and scientists have been paying increasing attention to "long COVID" for several months now. See, for example, this feature from The BMJ fro

This isn't a study, and scientists have been paying increasing attention to "long COVID" for several months now. See, for example, this feature from The BMJ from July: https://www.bmj.com/content/370/bmj.m2815 https://www.bmj.com/content/370/bmj.m2815 Alternatively, data from the UK in June suggests that 10% of people with COVID have symptoms that last for more than three weeks: https://covid.joinzoe.com/post/covid-long-term https://covid.joinzoe.com/post/covid-long-term If the number really is 10%, that's significant. This letter is merely suggesting further research; I think it's far from fear-mongering.