Sorry, forgot to check back here after posting... not 100% sure I have one source but here's one from a quick search: https://www.washingtonpost.com/health/202

Sorry, forgot to check back here after posting... not 100% sure I have one source but here's one from a quick search: https://www.washingtonpost.com/health/2020/08/08/asymptomatic-coronavirus-covid/ https://www.washingtonpost.com/health/2020/08/08/asymptomati... Specifically this line: > Or, as a paper published Tuesday in Science suggested, it could trace back to previous encounters with other coronaviruses, such as those that cause the common cold.