Covid-19 breakthrough infections after vaccination are possible. But don’t worry. - Vox.com

According to clinical trial data, the Pfizer/BioNtech vaccine is 95 percent effective at preventing Covid-19 disease.

The one-dose vaccine from Johnson & Johnson is between 66 and 72 percent effective (and higher at preventing severe disease).

That may seem even more puzzling since the clinical trials of tens of thousands of people reported that these vaccines were 100 percent effective at preventing hospitalizations.