We really don't know this for sure because there are so many false positives due to PCR hitting on fragments of the virus in people's systems but they never really had the symptom. I believe and predict in several years it will be found out that this was less deadly than the flu and was less contagious than the common flu.
Seen several responsible studies (IMO) that show just before, and just after, the appearance of symptoms is the most infectious time of infectees.