Usually yes, but there are three factors working against:
a) The long incubation period means no selective pressure to stop it becoming more serious. If it takes 3 weeks to kill you and you can spread it around for at least a week, so becoming more deadly would not really be that harmful to the viruses ability to spread
b) There is evidence that it is mutating rather fast which means more possibilities are being explored, it increases the likelyhood of something bad happening before we get a vaccine.
c) Its everywhere. With so much viral material about and accounting for b) it is also more likely we hit the unlucky jackpot.
Originally Posted by: Quantum