What to Know About Serious Adverse Effects and Deaths in the Moderna Vaccine Data

There were 13 deaths, but none are considered related to the vaccine

Credit: NurPhoto/Contributor/Getty Images

On Thursday, a panel of medical experts met to discuss the Covid-19 vaccine produced by Moderna, with the goal of deciding whether to recommend emergency use approval of the vaccine to the Food and Drug Administration (FDA). Among the many topics they covered in the eight-hour livestream, they discussed deaths and serious adverse events documented in Moderna’s data.

This information was included in a briefing document published by the FDA ahead of Thursday’s meeting. As in Pfizer’s trial data, which showed that six people had died but that none of those deaths were related to the vaccine, the Moderna data also included some deaths. Thirteen people in Moderna’s 30,000-person trial died as of December 3. Seven of those people were in the placebo group and didn’t receive the vaccine, and six were in the group of people who got the vaccine. None of the deaths were deemed related to the vaccine treatment.

It’s worth noting, for context, that the deaths of over 307,000 Americans have been attributed, definitively, to Covid-19.

Of the people who died in Moderna’s vaccine group, two were over the age of 75 and had preexisting cardiac disease. One of them died from a cardiopulmonary arrest after the first dose, and the other died of a heart attack after the second dose. Another person was 70 years old with cardiac disease and was found dead at home 57 days after getting the second dose.

One person who died was 72 years old and had Crohn’s disease and short bowel syndrome. After getting the second dose, they were hospitalized for thrombocytopenia (low levels of platelets in the blood) and acute kidney failure due to obstructive kidney stones, and complications led to multiorgan failure and then death.

Another person was 56 years old, with hypertension and chronic back pain that was treated with opioids. This person died, 37 days after getting the first dose, with head trauma listed as the official cause. A sixth person died of suicide 21 days after the first dose.

“These deaths,” notes the FDA report, “represent events and rates that occur in the general population of individuals in these age groups.”

Moderna’s data documented some serious adverse events (SAEs) too. One person had intractable nausea the day after receiving the second dose. Two had facial swelling days after getting the second dose, and both of them had a history of getting cosmetic dermal filler injections in their cheeks. Another person reported swelling in the lips two days after vaccination; they had previously received cosmetic dermal fillers injected into their lips. All of these people recovered with the help of antihistamines or a steroid course, and an expert noted that these risks would be included in the prescribing documents.

Nonserious adverse effects included pain at the injection site, fatigue, headaches, muscle and joint pain, and chills — common side effects related to vaccination. People in the vaccine group had higher rates of lymphadenopathy (specifically, swelling of the lymph node in the armpit and tenderness in the vaccination arm) and hypersensitivity events like rashes and hives, though nobody in the trial reported anaphylaxis. (For comparison, a handful of people with a history of severe allergic reaction have experienced anaphylaxis after getting the Pfizer vaccine.)

Three people in the vaccine group also developed Bell’s palsy, a condition in which half the muscles in the face temporarily become paralyzed or weakened. All of the people who had Bell’s palsy had preexisting conditions that make it hard to pin the cause on the vaccine, but “considering the temporal association and biological plausibility,” the FDA paper notes, “a potential contribution of the vaccine to the manifestations of these events of facial palsy cannot be ruled out.” The FDA recommends further surveillance of this condition if the vaccine gets an EUA. Researchers have previously raised concerns about Bell’s palsy as an adverse event of other vaccines (in adults and in children), but there does not appear to be a consensus on this question.

In a Q&A following the safety segment, Paul Offit, MD, director of the Vaccine Education Center and professor of pediatrics at Children’s Hospital of Philadelphia, pointed out that the rates of Bell’s palsy in both Moderna’s and Pfizer’s trials were higher than known baseline levels (about 40,000 people in the United States annually), noting, “I’m not quite sure how we are so comfortable with this being a background rate.” Rachel Zhang, MD, a medical officer on the FDA panel who presented the safety data, assured him, “This is something we’re looking into and thinking a lot about.”



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Yasmin Tayag

Yasmin Tayag


Editor, Medium Coronavirus Blog. Senior editor at Future Human by OneZero. Previously: science at Inverse, genetics at NYU.