Also important and useful, but that's a different percentage. That's the percentage reduction as compared to a non-vaccinated (hopefully otherwise matched) group. This is the percentage of the population (here, healthcare workers) who got it. Which, frankly, is the percentage I care more about, personally, although for Phase 3 testing of vaccines of course the percentage you're talking about is what matters.

Given that my daughter, who got the Pfizer vaccine, is unlikely to be exposed to covid-19 virus MORE often than a typical healthcare worker, this is good news. I wish we had as good a study for Moderna and J&J, but hopefully we get one soon.