Anaphylactic allergic reactions rare after the Pfizer-BioNtech vaccine. And unlike severe covid-19, they are almost always treatable

A new paper published in the Center for Disease Control and Prevention's Morbidity and Mortality Weekly Report looks at the rate of anaphylaxis during the first 1,893,360 administrations of the Pfizer-BioNTech covid-19 vaccine. 175 cases of interest were submitted to the Vaccine Adverse Event Reporting System (VAERS). A total of 21 cases of the 175 were deemed to be true anaphylaxis (defined as an allergic reaction with "systemic" manifestations, which can range from swelling of face and airway, to low blood pressure) from the vaccine, but this represented a rate of only 11 per one million doses of vaccine administered. More importantly, 17 cases (81 percent) were in persons with a documented history of allergies or allergic reactions, and 7 cases (33 percent) were in persons with a history of anaphylaxis. Most cases of anaphylaxis occurred on average within 13 minutes (range: 2-150 minutes) of receipt of the vaccine. 20 of 21 cases recovered well and returned home, and information on the outcome of the one remaining case was "lost to follow-up." 

The remainder of the 175 cases were deemed either to not be anaphylaxis allergic reactions or to be nonallergic adverse events, the latter which was mostly vasovagal (i.e. lightheadedness, "feeling woozy") or anxiety-related from getting the vaccine. 

Overall, the rate of anaphylaxis from the first ~1.9 million doses of the Pfizer-BioNtech vaccine appears very rare. The Centers for Disease Control recommends a short observation period after administration of the vaccine given the above data. 

Experts fear that as the vaccine is rolled out for mass distribution, people will be scared by such stories. That's why it is important to remember that anaphylaxis is treatable, especially when under direct medical care already (i.e. an observation period). On the other hand, covid-19 can kill and cause long-term suffering in many more. 

Research Section Editor


Maximizing vaccine uptake

Achieving herd immunity by vaccination in a timely fashion was always going to prove a heavy lift. While the federal government did determine allocation of vaccine supplies, leaving the states to decide their individual prioritization risked chaos and confusion. Combined with hesitancy around the vaccine, based on deep-seated mistrust of the government and concern for politicization of the development process, too many members of the public and even some in the healthcare workforce are reluctant to be among the first to get vaccinated. Against this backdrop, data from the Centers for Disease Control and Prevention (CDC) suggests that nearly 70 percent of the seventeen million distributed doses remain unused in freezers.

To address this slow uptake, state leaders have turned to multiple solutions. Some, like New York Governor Andrew Cuomo have discussed fining hospitals that do not use their supplies. Others have given deadlines for healthcare workers to receive their first dose or be moved to the back of the line. 

On Wednesday, the Department of Health and Human Services (HHS) Secretary, Alex Azar, announced a partnership with nineteen pharmacy chains with a combined national reach of forty thousand locations to make supplies more readily available to a broader segment of the population, as well as emphasizing that the priority tiering represent "recommendations, and they should never stand in the way of getting shots in arms." Various

  • Convalescent plasma: a rare win, if you squint hard enough
  • States call in National Guard to help speed vaccination efforts
  • A whole new world of possibilities for Biden. A flipped Senate has pandemic implications

  • Modeling the most effective vaccine rollout strategy. Should second doses be reserved? Or should more people get vaccinated now and play catch-up on the booster later?
  • Abortions plummeted during Texas' policy to postpone most surgeries and medical procedures during March and April, 2020
  • Convalescent plasma: a rare win, if you squint hard enough