frankv:

 

Fred99:

 

You probably shouldn't shouldn't ramp up first dose rollout until sufficient vaccine for second dose is shipped, or if that goes awry you'll be stuck with a large number of people in the population with unknown immunity, which would be a huge spanner in the works for any "exit plan".

 

 

Are there any stats on the efficacy of the second dose versus the time between the two doses? Will it be better or worse if the second dose is administered (say) 30 days after the first, and by how much?

 

IIRC, single dose efficacy is about 70%? So, although it's not as good as two doses, it's better than nothing.

 

i.e. can we just get lots of first doses administered, even if that means there's some delays in getting the second dose done?

 

 

 

I don't know.  I think the peak efficacy of the single dose of Pfizer is actually much higher than 70% - IIRC about 90%.  But without large enough human trials then efficacy over a period of time isn't known - it could be just short term and not good enough. With the trials which have been done based on the two dose regimen, they'd need to test using a different regimen to know efficacy, but also side effects.

You could "short cut" human trials to look at antibody neutralisation (in vitro), but assuming that those results correlate with real immunity is making assumptions - which could be dangerous.

If I was to make a guess, I'd say 3 weeks or 6 weeks gap probably makes no difference, it might be even better with a longer gap, but I'm definitely not an expert, and I doubt that experts know. 

When you're mass vaccinating (close to) an entire population - then throwing them to the wolves so to speak by "opening up" with an exit plan, you'd want to be very confident you've got things right.