One recent study of Israeli health care workers published in the New England Journal of Medicine offers a glimpse of the risk of long Covid after a breakthrough infection. Among 1,497 fully vaccinated health care workers, 39 of them — about 2.6 percent — developed breakthrough infections. (All of the workers were believed to be infected after contact with an unvaccinated person, and the study was conducted before the Delta variant became dominant.)

While most of the breakthrough cases were mild or asymptomatic, seven out of 36 workers tracked at six weeks (19 percent) still had persistent symptoms. These long Covid symptoms included a mix of prolonged loss of smell, persistent cough, fatigue, weakness, labored breathing or muscle pain…

“People have said to me, ‘You’re fully vaccinated. Why are you being so careful?’” said Dr. Robert M. Wachter, professor and chair of the department of medicine at the University California San Francisco. “I’m still in the camp of I don’t want to get Covid. I don’t want to get a breakthrough infection.”