> In fact, it's far from clear
Seems clear from my perspective. Two doses are recommend by manufacturers. Anything more or less is pure speculation at best. Why speculate in absence of a way to test your hypothesis?
Seems clear from my perspective. Two doses are recommend by manufacturers. Anything more or less is pure speculation at best. Why speculate in absence of a way to test your hypothesis?
There are two lines of evidence. The first is empirical. It It appears that one dose of Moderna _is_ highly effective, perhaps 85% or more. Note the treatment-control divergence after about fourteen days [1]. The second is theoretical. From our ample medical experience with other vaccines, there is strong prior reason to think that one dose is likely to work well, and that a second shot in the distant future would be even better than a second shot after three or four weeks. Booster shots are given a.) as backup for people who don't seroconvert after one dose b.) to trigger a secondary immune response. In light of a.), we shouldn't be surprised by the 85% number (most people seroconvert; there's no partial immunity, you either seroconvert or you don't). In light of b.), we should be very skeptical of the four week interval, especially since the secondary response takes about two weeks to develop. It's shorter than the interval for every other vaccine.
[1] https://arstechnica.com/science/2020/12/fda-releases-data-on... [2] https://www.cdc.gov/vaccines/schedules/hcp/imz/child-adolesc...
Yes, two doses are almost certainly better than one. But those are not the choices.
When there are far fewer doses than the number of people to vaccinate, the question is if it's better to give N people 2 shots, or 2N people 1 shot.
The test data looks like 1 dose gives ~80% protection vs ~95% for 2 doses. The 2x80% scenario is clearly better than 1x95%.
And, of course, everyone would get the second dose as soon as production catches up.