The One Vaccine Efficacy Number That Truly Matters

Something sounds fishy when public-health experts advise us to take whatever vaccine is available even though some vaccines show much more promising efficacy numbers than others. And it’s understandable that people would want to shop for the best vaccine. Americans are accustomed to the idea of consumer choice in pharmaceuticals — why else would we have so much direct-to-consumer drug advertising? But cut through the noise and there’s only one thing that really matters: All three FDA-authorized vaccines seem to work equally well — close to 100% — at preventing hospitalization and death.

That message has gotten diluted in the reporting around the efficacy numbers for different vaccines. The efficacy numbers associated with the Moderna and Pfizer vaccines came in at around 95%, while the newly approved Johnson & Johnson vaccine has shown a less impressive 72% in the U.S., and even lower in other countries. As risk-communication expert Peter Sandman says, people remember from school that 95% usually earns an A, and 72% a C at best.