Vaccine fears: Concerns about adverse events and long-term effects of COVD-19 vaccines

Staff Photo by Matt Hamilton / Nursing supervisor Nadine Stone fills syringes with vaccine at First Baptist Church in Cleveland, Tennessee, on March 30.

Editor's Note: The following is the fourth in a series of stories addressing common concerns that can contribute to COVID-19 vaccine hesitancy. Read previous installments at

Six months ago marks when the first American outside of clinical trials received a COVID-19 shot, and many people who are vaccine-hesitant may worry that enough still isn't known about potential adverse events or long-term effects of vaccination.

Nearly 315 million doses of COVID-19 vaccine have been administered in the United States so far, and 147.8 million Americans are now fully vaccinated under the "most intense safety monitoring" in the nation's history, according to the U.S. Centers for Disease Control and Prevention.

The CDC and other government agencies are continually monitoring vaccine safety, but the government database that tracks adverse reactions to vaccines - the Vaccine Adverse Event Reporting System or VAERS - can easily be misinterpreted for those who don't understand how it works.

For example, VAERS allows anyone to report any adverse event following vaccination regardless of whether there's proof the vaccine caused the problem.

Although true adverse vaccine events are extremely rare, they do happen, and it's important to know the difference between side effects - which are a normal immune response to vaccination - and adverse events, as well as understand the context in which adverse events occur.

This week, the Times Free Press has been tackling some of the common questions surrounding COVID-19 vaccine safety starting with, "How can the COVID-19 vaccines be safe if development was rushed?"; "What's in a COVID-19 vaccine?"; and "How do the COVID-19 vaccines work?" With this installment, we'll look into:

Question: How common are adverse events, and how do we know there won't be long-term effects from COVID-19 vaccines?

Answer: The CDC states,"More than 310 million doses of COVID-19 vaccines were administered in the United States from December 14, 2020, through June 14, 2021. During this time, VAERS received 5,343 reports of death (0.0017%) among people who received a COVID-19 vaccine."

The U.S. Food and Drug Administration requires health care providers to report any death after COVID-19 vaccination to VAERS, even if it's unclear whether the vaccine was the cause, and an average of nearly 8,000 Americans die each day from all causes, based on 2019 data from the CDC.

Daniel Salmon, the director of the Institute for Vaccine Safety at Johns Hopkins School of Public Health, said that while the VAERS system can be useful, it has limitations.

"There's lots of over-reporting. There was a study that looked at VAERS reports of autism, and the vast majority of autism reports came from lawyers," Salmon said.

He said if someone got a vaccine and then their dog was hit by a car, they could file a report.

"That's a ridiculous example, but it's true," he said. "There's good things about VAERS. First, it gives people and doctors a place to report things, and that's good. People should have a place to report things. It's not terribly expensive. It can be useful for picking up health events you didn't expect."

The system helped catch a string of rare blood clots with low platelet counts known as TTS associated with the Johnson & Johnson COVID-19 vaccine.

As of June 14, more than 11.7 million doses of the J&J/Janssen COVID-19 vaccine had been given in the U.S., and the CDC and Food and Drug Administration have identified 36 confirmed reports of people who later developed TTS. Some of those people died.

"That's an incredibly unusual medical phenomenon. So when you look at that, you can say, 'Wow, these are probably due to the vaccine,'" Salmon said. "If you look at something like heart attacks, or death, or Guillain-Barre syndrome, that happens absent vaccination. So just because you see some VAERS reports, it doesn't really tell you if the vaccine is causal."

Other adverse events related to the three COVID-19 vaccines available in the U.S. include anaphylaxis, a severe but treatable allergic reaction, which has occurred in approximately 2 to 5 people per 1 million vaccinated in the U.S., according to the CDC.

CDC and FDA have also confirmed 323 reports of myocarditis or pericarditis - two types of heart inflammation - after vaccination, and officials are investigating whether there is a relationship to COVID-19 vaccines.

As for the other 5,343 reports of death, the CDC states, "A review of available clinical information, including death certificates, autopsy and medical records, has not established a causal link to COVID-19 vaccines."

While on one hand there's overreporting in VAERS, Salmon said there's also underreporting, since not everyone knows about the system or may only have mild reactions.

"If you understand it for what it is and it's used in a complementary way with other systems, it has value. But it's really easy to misrepresent what VAERS means and what [it] doesn't," he said.

As far as long-term effects of the vaccines, Salmon agrees that "we can't say with absolute certainty that there won't be some problem 20 years later because of COVID vaccines."

But throughout the history of vaccines, adverse events have always occurred within the first six months after vaccination, he said, and "we don't know what the long-term consequences of COVID are, either."

"People get upset about what they don't know, understandably. But you know, lots of viruses cause long-term problems that you don't find out about for a long time," Salmon said. "For many people COVID is not serious. It's true. But for many viral infectious diseases, they're not serious - seemingly - at the time, and you find out later it causes problems."

For example, HPV infections are usually asymptomatic but are the No. 1 cause of cervical cancer and can cause other cancers, hepatitis B rarely causes symptoms but is a leading cause of liver cancer and chicken pox is normally a mild infection but can resurface later in life as a much more painful rash.

"There's lots of examples where a virus at the time may seem like not a big deal, and decades later it's really bad - it manifests as some other sort of disease," he said. "There just aren't examples of that with vaccines. In fact, most problems are pretty quick."

Contact Elizabeth Fite at or follow her on Twitter @ecfite.