Happy Saturday — here’s some quick takes.

Vaccines are really good

When you read in the press that a vaccine is 90 percent effective vs another one that’s only 70 percent effective, do you know what that means? It turns out that what everyone is measuring in their Covid trials is the share of people in the control group who develop symptoms vs the share of people in the treatment group. That focus on symptoms has a bad news aspect that’s been widely publicized — they measured symptoms rather than doing constant PCR tests so some of the vaccinated people may have had asymptotic infections, and it’s possible that vaccinated people can still spread the virus.

Less widely publicized is the good news: None of the people in the Pfizer/Moderna treatment groups died or even fell seriously ill and had to be hospitalized.

This is typical of vaccines. For virology reasons that I don’t really understand, flu vaccines have very low efficacy as measured in this way. One of the main reasons doctors r…