Vaccine recipients are concerned, and scientists are stumped

Anecdotes can teach us things that statistics can’t: People who have been vaccinated appear to be catching the coronavirus at an alarmingly high incidence. But it’s unclear how often they do it or how likely they are to spread the illness to others. And now there’s growing fear that people who have been vaccinated may be more susceptible to serious illness than previously assumed.

There’s a dearth of scientific studies with concrete answers, leaving public policy makers and corporate executives to formulate plans based on fragmented information. While some are renewing mask mandates or delaying office reopenings, others cite the lack of clarity to justify staying the course. It can all feel like a mess.

“We have to be humble about what we do know and what we don’t know,” said Tom Frieden, a former director of the Centers for Disease Control and Prevention and the head of the nonprofit Resolve to Save Lives. “There are a few things we can say definitively. One is that this is a hard question to address.”

Absent clear public health messaging, vaccinated people are left confused about how to protect themselves. Just how vulnerable they are is a key variable not just for public health officials trying to figure out, say, when booster shots might be needed, but also to inform decisions about whether to roll back reopenings amid a new wave of the virus.  On a smaller scale, the unknowns have left music lovers unsure if it’s OK to see a concert and prompted a fresh round of hang-wringing among parents pondering what school is going to look like.

In lieu of answers, what has emerged is a host of case studies providing somewhat different pictures of breakthrough infections. Variables including when the surveys were conducted, whether the delta variant was present, how much of the population was vaccinated and even what the weather was like at the time make it hard to compare results and suss out patterns. It’s difficult to know which data might ultimately carry more heft.

“It’s quite clear that we have more breakthroughs now,” said Monica Gandhi, an infectious disease expert at the University of California, San Francisco. “We all know someone who has had one. But we don’t have great clinical data.”