Anaphylaxis Cases After COVID Vaccine Rising But Still Rare: CDC

Kerry Dooley Young

January 06, 2021

Editor's note: Find the latest COVID-19 news and guidance in Medscape's Coronavirus Resource Center.

Healthcare providers should be ready to treat rare cases of anaphylaxis following administration of COVID-19 vaccines, federal medical officials have urged. The officials also stressed the importance of continuing vaccinations, despite reports of the rare side effect.

There have been 29 cases of anaphylaxis to date following administration of a COVID-19 vaccine, officials from the Centers for Disease Control and Prevention (CDC) said on a Wednesday call with reporters.

The severe allergic reaction, which appears to be rare, can happen with either the Pfizer-BioNTech vaccine or the rival Moderna product. The Food and Drug Administration (FDA) granted emergency use authorizations for these two vaccines last month.

Even with the cases seen to date, the COVID-19 vaccines remain a "good value proposition," said Nancy Messonnier, MD, director of the CDC's National Center for Immunization, on the call.

There have been about 11.1 cases of anaphylaxis per million doses with the Pfizer-BioNTech COVID-19 vaccine, which is higher than the estimated 1.3 cases per million doses with influenza vaccines, she said. But the low risk of anaphylaxis must be balanced against the threat of COVID-19, which currently claims about 2000 lives a day in the United States, she said. In addition, many people are reporting long-term complications with COVID-19 even if they recover.

Kept in context, the data on anaphylaxis should not scare people away from getting a COVID-19 vaccine, she said.

"Their risk from COVID and poor outcomes is still more than the risk of a severe outcome from the vaccine," Messonnier said. "And fortunately, we know how to treat anaphylaxis."

Messonnier urged healthcare workers administering COVID-19 vaccines to be prepared.

"Anybody administering vaccines needs not just to have the EpiPen available, but frankly, to know how to use it," Messonnier said.

MMWR Details

The CDC on Wednesday also provided an update on anaphylaxis in Morbidity and Mortality Weekly Report (MMWR).

The information included in the report was based on cases reported with the Pfizer-BioNTech vaccine — the first to get emergency use authorization from the FDA. On the call with reporters, CDC officials confirmed there have been additional reports since then and anaphylaxis has been reported with both the Pfizer-BioNTech and Moderna vaccines. CDC officials said they could not give a breakdown of how many cases were linked to each of these products at this time.

Between December 14 and 23, monitoring by the Vaccine Adverse Event Reporting System detected 21 cases of anaphylaxis after administration of a reported 1,893,360 first doses of the Pfizer-BioNTech COVID-19 vaccine. Most reactions — 71% — occurred within 15 minutes of vaccination.

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