Atlanta—Safety data on the Pfizer-BioNTech and Moderna vaccines for COVID-19 shows rates of anaphylaxis generally lower than previously calculated and few, if any, related deaths.

The research was presented at the Advisory Committee on Immunization Practices (ACIP) meeting by Tom Shimabukuro, MD, of the CDC.

The CDC preliminarily reported that anaphylaxis occurred in 11.1 cases per million doses administered from December14 to December 23, 2020, for the Pfizer-BioNTech vaccine and 2.5 cases per million doses administered from December 21, 2020, to January 10, 2021, for the Moderna vaccine. More recent rates, estimated through January 18, show an anaphylaxis rate of 5.0 cases per million doses for the Pfizer-BioNTech vaccine, and 2.8 cases per million doses for the Moderna vaccine, according to the presentation.

Most of the vaccines, 61%, were received by women, Dr. Shimabukuro points out.
In terms of mortality related to vaccination, data from the Vaccine Adverse Event Reporting System (VAERS) shows 196 possible deaths due to any cause. The presentation cautions that those reports are of deaths following vaccination and should not be assumed to be related to the vaccination itself.

Of those, recipients had a median age of 79 years, although 43% were younger than age 65 years. Most of the mortality occurred in women living in long-term care facilities (LCTF). In terms of vaccine received, 113 got the Pfizer-BioNTech product, and 83 received the Moderna shot.

A closer look at what occurred in long-term care residents—who, with frontline healthcare workers, were prioritized to receive the first vaccines—helps elucidate what occurred and whether there was any connection with immunization.

“Mortality in LTCF residents is high and substantial numbers of deaths in this population will occur following vaccination as temporally associated coincidental events,” the report states.

In fact, the presentation explains that mortality was lower among vaccinated versus unvaccinated residents within the same facilities and compared to residents in not-yet-vaccinated facilities.

“Findings suggest that short term mortality rates appear unrelated to vaccination for COVID-19 in skilled nursing facility residents,” the presentation points out. “This study underscores the value of having an analytic infrastructure to support near real-time monitoring of adverse events and safety during rapid vaccine deployment in this vulnerable population.”

In concluding, Dr. Shimabukuro advises that 23.5 million COVID-19 vaccine doses have been administered in the United States and that, overall, “the safety profiles of COVID-19 vaccines are reassuring and consistent with that observed from the pre-authorization clinical trials.”

While anaphylaxis has been observed following mRNA COVID-19 vaccines, it is a rare event, he adds, noting, “Additional population-based monitoring systems will continue to gather safety data safety as vaccination increases and the immunization program broadens.”

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