More than 23 million doses have been administered so far, with a low incidence of severe adverse effects. Recipients typically have experienced headache, fatigue, and muscle soreness after the second injection, with some presenting with fever and chills.

As for anaphylaxis, a severe adverse effect that drew early concerns, 50 cases have been tied to Pfizer’s vaccine and 21 have been tied to Moderna’s product. Although scientists still do not know why, most cases affected women. Meanwhile, approximately 200 deaths have occurred, many of them among residents of long-term care facilities. However, these deaths do not appear to be linked to the vaccine.