It's an important metric because earlier indicators aren't as useful. The rate of new cases is tricky because we don't really care if someone gets COVID-19 anymore than we care if they get the common cold, assuming they have only mild symptoms and fully recover. Hospitalizations are the first unambiguous metric we have to know there is a serious problem that may require a dramatic response.
> It's an important metric because earlier indicators aren't as useful.
Sure they are. They're less precise, but they're more useful, because they're more likely to let you combat the spike before it gets out of control.
It's like a smoke alarm. Maybe it's going off because it's over-sensitive and someone just took a shower... but it's a better early warning system than waiting for active flames to appear.
You use cases to determine if you need to react to stop spread since you get results faster. You use hospitalization to determine the time-lagged efficacy of your interventions since it is more precise. What is more useful depends on what you are trying to get out of it. In this particular case, we are discussing the efficacy of vaccination and how that might influence restriction lifting, so you want to err on the side of caution and accuracy and use hospitalization.
I agree, but once vaccinations are widespread and we are confident that severe illness will be very rare, it would be hard to take drastic measures based only on the rate of new cases. There could be a huge surge of cases but we would expect a low hospitalization rate, so we would likely want to wait.
Immunity through vaccination + natural immunity is getting closer to 'widespread' now (in the US). We are likely near 30%, and of that 30%, a growing proportion is the most vulnerable sections of the population. A spike in cases now would be increasing less connected to a future rise in hospitalizations. I think its fair to say, that if we do not see a spike within the next 3-4 weeks, we are in the clear for future spikes. By April 1st, we should be nearing 40%, with the difference primarily being now vaccinated old and immune compromised people.
