Situation Report

Allergic reactions reported in two health workers who received a dose of Pfizer’s vaccine in Alaska this week have reignited concerns that people with a history of extreme immune flare-ups might not be good candidates for the newly cleared shots.

The two incidents follow another pair of cases in Britain. Three of the four were severe enough to qualify as anaphylaxis, a severe and potentially life-threatening reaction. But all four people appear to have recovered.