[EdFNJ]

Originally Posted by matandch

The second shot is a booster to push efficacy up to the promised 95%. You will have up to 80% efficacy with just 1 shot. You do not have to start over.

80% Source please.

Pfizer said the late-stage trial found its shot was about 52% effective after the first dose, with study results showing protection starting as early as 12 days after receiving it. A week after the second dose, the shot's effectiveness rose to 95%, Pfizer said its study found.Jan 8, 2021

and

Doctors tell ABC7 News that the first vaccine shot gives 50 percent immunity, which doesn't kick in for a week with the Pfizer vaccine and two weeks with the Moderna vaccine.

and

Pfizer’s vaccine was 52% effective after the first shot and 95% after the second one.

How effective is a single vaccine dose against Covid-19? - BBC Future
Pretend it didn't happen – expert advice on how to behave after receiving a single dose of any of the Covid-19 vaccines.