Covid-19 Vaccine Trial Volunteers Note Occasional Harsh Side Effects

Covid-19 Vaccine Trial Volunteers Note Occasional Harsh Side Effects

Most report mild side effects, but those experiencing worse still recommend the shots

Jocelyn Edwards wasn’t sure she got Moderna Inc.’s MRNA -6.94% experimental Covid-19 vaccine or a placebo when she received her first of two doses in August. Hours after the second shot, she said she was sure it was the genuine article.

“I woke up around midnight freezing,” said the 68-year-old retired nurse. “For the next 24 hours I had intense chills, serious neck pain, headache, all my joints were aching.” She had a fever that peaked at 102.4 and poured out so much sweat that she lost 3 pounds, she said. The following day she woke up and felt fine.

Ms. Edwards, like the other 30,000 volunteers who took part in Phase 3 clinical trials for Moderna’s Covid-19 vaccine, wasn’t told whether she got the vaccine or a placebo. However, she said a trial researcher attributed her symptoms to her body mounting a strong immune response to what was most likely the vaccine. “It’s better having 36 hours of feeling really rough than getting Covid,” she said.

Moderna declined to comment for this article.