Getting her fourth and fifth shots was trickier. By July, pharmacy records in the Houston area where she lives finally showed her prior shots. Armed with a doctor’s note explaining that she hadn’t developed antibodies, Ms. Ricks convinced a pharmacist to give her two doses of the Pfizer vaccine over the summer.

>"People with compromised immune systems are getting unapproved fourth or fifth Covid-19 shots, despite uncertainty about their safety or effectiveness."