Handle9:

 

When there's an outbreak being fully vaccinated is far more likely to have good outcomes than having one shot.

 

You can't get unvaccinated but you can only get one shot and not go back if there's a long time between shots.

 

Given our currently bottleneck is the ability to administer doses, any second doses delayed would be replaced by people having their first dose.

The data is shaky as to if this is a net benefit. Data from different sources seem way apart. As one example of data pfizer after one dose offers 48.7% protection vs delta, and after two doses offers 88.0% protection. This would imply that two people getting first doses offers net greater protection to society than a single person getting both doses.

https://www.cidrap.umn.edu/news-perspective/2021/07/study-2-covid-vaccine-doses-much-more-effective-1-against-delta

But I don't think this can be concluded either way when studies that show the situation the other way around are also considerd.

One of the advantage of having a lot of people between 3 and 8 weeks after their first dose is that on detection of community transmission in an area, all those people can immediately be recommended to have their second dose, and panic 2nd dose clinics stood up in the area of the outbreak. Much quicker to finish off a bunch of peoples vaccination than to start on a bunch of vaccinated people.

Is their any evidence that a longer waiting period between doses impacts 2nd dose turnout? I doubt it would be material.