Severe allergic reactions to the Pfizer vaccine are exceedingly rare

Out of almost 2 million vaccine doses administered, there have only been 21 cases of severe allergic reactions and no fatalities, a CDC report shows. It doesn’t make sense to worry about the vaccines more than the virus.

The pros overwhelmingly outweigh the cons

Data from the Centers for Disease Control and Prevention (CDC) show that between December 14 and December 23, 1,893,360 COVID-19 shots were administered. Out of these, 21 cases

“This averages out to a rate of 11.1 anaphylaxis cases per one million doses administered,” senior CDC official Nancy Messonnier told reporters at a briefing.

Out of these 21 cases, 4 were hospitalized and all but one was released (at the time the study was conducted). While the CDC, Pfizer, and multiple health bodies are still investigating the cause of these side effects, it’s still just 4 hospitalizations out of 4 million shots.

“This is still a rare outcome,” Messonnier, head of the CDC’s National Center for Immunization and Respiratory Diseases, said during the media briefing Wednesday. “Right now, the known and potential benefits of the current Covid-19 vaccines outweigh the known and potential risks of getting Covid-19.”

The average anaphylaxis rate for the COVID-19 vaccine is 11.1 cases per one million doses administered. While this is higher than in the flu vaccine (which causes an estimated 1.3 cases per one million doses), thankfully, doctors have become quite good at dealing with anaphylaxis and special precautions were taken at every vaccination site, so there were no fatalities.

“Fortunately, we know how to treat anaphylaxis, and we’ve put provisions in place to ensure that at immunization sites, the folks administering the vaccine are ready to treat anaphylaxis,” says Messonnier.

The vast majority of vaccination produces no significant side effects, but it’s still entirely normal to have some side effects after a vaccine. The most common is redness and swelling around the injection site. Fatigue, fever, and headaches are also possible. For the COVID-19 vaccine, the most severe side effects (which happen in 1 in 100,000 doses) include hoarseness, dry cough, swollen tongue, and difficulty breathing.

Severe reactions are very rare

To ensure the safety of the vaccination campaign, the CDC has asked people who have had a severe reaction to the first dose to not take the second one. If you have had a severe allergic reaction to any ingredient in an mRNA COVID-19 vaccine, you should not get either of the currently available mRNA COVID-19 vaccines.

In particular, Clark advises anyone with a known allergy to polyethylene glycol or polysorbates (two compounds used in the pharmaceutical, cosmetic, and food industry) to avoid getting vaccinated. The CDC advises that people with allergy concerns consult their clinician because, in many cases, even people with a history of allergies can get vaccinated.

“There’s a big difference between somebody who had a mild allergic reaction in their childhood, versus somebody who had a severe allergic reaction last week,” Messionner said. “It’s going to be really important to have a clinician help a patient exercise judgment.”

With side effects so very unlikely and so manageable, it only makes sense to get the vaccine, unless your clinician (or another official responsible) personally recommends against it. The threat of the virus is present and real, and much, much stronger than that of vaccine side effects.

The approved vaccines are safe, according to the European Medicines Agency (EMA), the US Food and Drug Administration (FDA), and the World Health Organization (WHO) — otherwise, they would have not passed the approval.

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About Mihai Andrei

Andrei's background is in geophysics, and he's been fascinated by it ever since he was a child. Feeling that there is a gap between scientists and the general audience, he started ZME Science -- and the results are what you see today.

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