[zaroth]

The actual study results show the vaccine is highly effective within 10 days of the first dose.

Honestly a bit shocked based on the results and the number of lives that could be saved by effectively doubling the number of available doses that they didn’t try to get it modified to a single dose regimen.

Seems to me like just another way the FDA has screwed up this whole rollout.

[rleigh]

Two doses is very common for vaccines because this is based upon how the immune system responds to real infections. The first dose will initiate a primary immune response. The second dose will act as a "challenge" to trigger a secondary immune response.

[ed25519FUUU]

It sounds like one dose is enough to make you much less likely to develop serious symptoms or symptoms at all, and two doses gives you close to immunity.

[rleigh]

Absolutely, after the first shot you do have immunity but it's not as fully developed compared with having two, so it will take longer to respond than with two, and that does present a larger window of opportunity for the virus to cause problems.