[BostonCard]

Suppose a large number of people chose to voluntarily forego or delay their 2nd shot, putting themselves as a cohort of people only getting the single dose.   Say, they wait 3 months or 6 months for their 2nd dose.

They would provide 3 benefits, at a risk to themselves,
1)  More people would get at least the first dose more quickly simply by their delay
2)  They could provide evidence for whether a single dose is effective.
3)  #2 could conceivable allow first doses to be declared sufficient, in time to finish vaccinations earlier.

Among the people that might decide this are health care workers who got their first dose first.  By being among the first, evidence from their experience would be available most quickly.

What does the current science suggest for the effectiveness of just one dose?  I’m assuming it reduces risk by some factor.  Is that correct?

For the Pfizer vaccine, the infection curves started to deviate at about the 10 day mark (after the first vaccine) and some people have suggested it is better to go for imperfect efficacy but get twice as many people vaccinated early.  Unfortunately we don't have enough data to know for sure.  The Moderna vaccine is similar, though not quite as clear (they were slow to accrue events in both arms until about day 20 so it's hard to tell if the vaccine is making a difference, but there's no reason why a single dose wouldn't offer at least partial protection).

The big unknowns are about how much protection it offers and how long the protection lasts.  Officially, the FDA has said that there isn't enough evidence about two doses, and certainly I wouldn't encourage anyone to engage in a high-risk activity until at least seven days after their second dose.

BC

[BostonCard]

Suppose a large number of people chose to voluntarily forego or delay their 2nd shot, putting themselves as a cohort of people only getting the single dose.   Say, they wait 3 months or 6 months for their 2nd dose.

They would provide 3 benefits, at a risk to themselves,
1)  More people would get at least the first dose more quickly simply by their delay
2)  They could provide evidence for whether a single dose is effective.
3)  #2 could conceivable allow first doses to be declared sufficient, in time to finish vaccinations earlier.

Among the people that might decide this are health care workers who got their first dose first.  By being among the first, evidence from their experience would be available most quickly.

What does the current science suggest for the effectiveness of just one dose?  I’m assuming it reduces risk by some factor.  Is that correct?

For the Pfizer vaccine, the infection curves started to deviate at about the 10 day mark (after the first vaccine) and some people have suggested it is better to go for imperfect efficacy but get twice as many people vaccinated early.  Unfortunately we don't have enough data to know for sure.  The Moderna vaccine is similar, though not quite as clear (they were slow to accrue events in both arms until about day 20 so it's hard to tell if the vaccine is making a difference, but there's no reason why a single dose wouldn't offer at least partial protection).

The big unknowns are about how much protection it offers and how long the protection lasts.  Officially, the FDA has said that there isn't enough evidence about two doses, and certainly I wouldn't encourage anyone to engage in a high-risk activity until at least seven days after their second dose.

BC