Author Response: Skeletal Muscle and Peripheral Nerve Histopathology in COVID-19

We are grateful for the interest in our research.¹ As mentioned in our study, hyperCKemia, myalgias, and myositis have been reported in patients with COVID-19, but it has remained unclear whether muscle damage is because of viral infection of muscle, toxic effect of cytokines, or another mechanism. Our autopsy study sought to explore that ambiguity.¹ Some have postulated that skeletal muscles and nerves are susceptible to direct SARS-CoV-2 invasion, but this is not proven. We found no evidence for direct invasion of muscle or nerve in our 35 autopsies.¹ This result was not necessarily due to our patients' asymptomatic presentations. We could not target symptomatic muscle or nerves because our patients were too weak to give a reliable history in this regard, with most of them on a ventilator. Furthermore, the virus was still evident in the lungs in all patients, as tested by PCR and by immunohistochemistry in 22 of the 35 patients at autopsy. It is important that another large autopsy series looking at muscle in 43 patients dying of COVID-19 found comparable features, and similarly, none had evidence of direct viral infection of muscle.²