[Tmarkwald]

Originally Posted by tuccillo

The correct way to interpret the statistics from the trials is as follows. If you are fully vaccinated and two weeks after your second shot, the probability of developing symptoms (look at the trial studies for the exact definition of what symptoms, how many symptoms, and the level of symptoms they call "positive") if you are exposed is reduced by 20x (95% efficacy) compared with not having been vaccinated. Your probability of developing symptoms if you are exposed and not vaccinated is not precisely known but is generally a small number. In the trials, they don't know who was exposed. So, the vaccine reduces this unknown, but small number, by 20x. Some early numbers from Washington state have the breakthrough rate at 0.01%. Also, if you are vaccinated, your probability of developing serious disease symptoms that lead to hospitalization and possibly death is essentially zero. By any objective measure, the vaccines are extremely effective at doing what we would hope they would do; prevent serious disease and death.

Very good explanation!