How unrelated health events can hamper COVID vaccination efforts

How unrelated health events can hamper COVID vaccination efforts
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COVID-19 vaccination programs are ramping up across the country. Each day, about 1.6 million people are vaccinated in the United States. That’s equivalent to vaccinating everyone in the city of Philadelphia or San Antonio each day. 

Vaccinating so many people means that very rare adverse events will occur. A tiny proportion of vaccine recipients will have severe allergic reactions: 6.2 per million for the Pfizer-BioNTech vaccine and 2.1 per million for the Moderna vaccine. Rapid medical care in the form of an injection of epinephrine quickly resolves the problem. Individuals who have had extreme reactions to injectable vaccines should check with their physician and be vaccinated only at facilities equipped to respond to an allergic reaction. Because over 90 percent of severe reactions occur within a half hour of vaccination, individuals at increased risk should wait for 30 minutes (rather than the usual 15 minutes) after vaccination before leaving the facility.

Unfortunately, but predictably, some vaccine recipients will develop a serious health problem days or weeks after receiving a vaccine. But it would be a mistake to jump to the conclusion that the vaccine ‘caused’ the problem. 


Every day over 8,700 people die in the U.S.  Some of these people will have been recently vaccinated. For example, on Jan. 5, legendary baseball player Hank Aaron, 86 years old, received a COVID-19 vaccination in a highly publicized event at the Morehouse School of Medicine in Atlanta. On Jan. 22, Aaron died from a massive stroke. The timing of the two events fueled speculation that the vaccine played a part in his stroke and death. However, this speculation was quickly and thoroughly rebutted by several medical experts who agreed that Aaron’s vaccination had nothing to do with his later stroke.

It’s a matter of numbers. Over 40 million people in the U.S. have been vaccinated for COVID-19 and many of the first people vaccinated were elderly residents of senior facilities. A number of them had a stroke or heart attack days or weeks after being vaccinated and some did not survive — but deaths in this population would be expected in any event and were not caused by their vaccination. The same pattern, but with relatively fewer fatalities, will take place as younger adults are vaccinated.  

Erroneously attributing adverse outcomes to the COVID-19 vaccine poses a significant threat to public health because it raises doubts among individuals about the safety of the vaccines. Media or social media reports can amplify those doubts, particularly among vaccine hesitant individuals and thereby increase the number of people likely to decline vaccination. The consequences are a reduced chance of achieving the 70 to 85 percent population immunity needed to establish ‘herd immunity’. And an even greater percentage of vaccination may be necessary because of the increased transmissibility of new variants of the coronavirus.

An informed public should be able to dismiss ill-considered or fabricated reports of COVID-19 vaccines being the cause of unrelated adverse events. As vaccination expands from health care workers and older Americans to the general population, detailed records are being maintained of the safety of the vaccines authorized for use by the Food and Drug Administration. The Centers for Disease Control and Prevention and FDA jointly manage a registry of vaccine adverse events leading to hospitalization or death, which permits the identification, tracking and public disclosure of possible risk factors. Other adverse event registries have been formed by networks of academic medical centers and large healthcare systems. The data from tens of millions of vaccinations has confirmed the excellent safety profile of the COVID-19 vaccines originally reported in their clinical trials. 

After 500,000 deaths, 40 percent of which could have been prevented, along with catastrophic personal and economic suffering, we should be vigilant in preventing misinformation from undermining vaccination rates and thereby dimming the first light at the end of a long, dark tunnel.

Mark A. Rothstein, J.D., is the Herbert F. Boehl chair of Law and Medicine and director of the Institute for Bioethics, Health Policy and Law at the University of Louisville School of Medicine. Carlton A. Hornung, Ph.D., M.P.H., is a retired professor of Medicine and of Epidemiology at the University of Louisville.