[M T]

Thanks for that.  I haven't been following vaccine hopes.

One of the studies I've seen indicated that the reintroduced cases of COVID-19 in Wuhan appeared to be less severe than the original cases. 

I can imagine several reasons for that (assuming the effect is real, which I didn't evaluate):
1) Earlier detection of the disease
2) Better prepared health care system
3) Change in the virus affecting its severity
4) More resistance in the people that got the reintroduced cases

#4 is one that could give me hope for a vaccine.  If the population was widely exposed to low levels of the virus (or maybe to inactive virus), then maybe their immune systems were in a better position to blunt the infection or to fight it off..

While we want a vaccine that conveys immunity, I'd be happy for an initial vaccine that reduced lethality by 50%.

[M T]

Thanks for that.  I haven't been following vaccine hopes.

One of the studies I've seen indicated that the reintroduced cases of COVID-19 in Wuhan appeared to be less severe than the original cases. 

I can imagine several reasons for that (assuming the effect is real, which I didn't evaluate):
1) Earlier detection of the disease
2) Better prepared health care system
3) Change in the virus affecting its severity
4) More resistance in the people that got the reintroduced cases

#4 is one that could give me hope for a vaccine.  If the population was widely exposed to low levels of the virus (or maybe to inactive virus), then maybe their immune systems were in a better position to blunt the infection or to fight it off..

While we want a vaccine that conveys immunity, I'd be happy for an initial vaccine that reduced lethality by 50%.