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Most people have some arm pain and fatigue after a COVID-19 vaccination, but serious side effects are rare. Scott Eisen/Getty Images
  • A new report from the Centers for Disease Control and Prevention (CDC) based on recent safety surveillance data shows the Pfizer and Moderna vaccines are safe and associated with few serious side effects.
  • People most generally have experienced mild pain at the injection site, fatigue, and headache.
  • Anaphylaxis is rare and typically occurs in people with a history of allergies.

All data and statistics are based on publicly available data at the time of publication. Some information may be out of date.

The Centers for Disease Control and Prevention (CDC) has released a new report summarizing the safety of the messenger RNA (mRNA) vaccines.

The report shows the Pfizer and Moderna vaccines are safe and associated with few serious side effects based on recent safety surveillance data of 22 million people.

As of Feb. 1, 31 million people in the United States have been vaccinated.

Most commonly, people experienced mild pain at the injection site along with fatigue and headache.

Anaphylaxis, or severe allergic reactions, to the vaccine remain rare. Most cases occurred within 15 minutes of vaccination. The vast majority of cases had a history of allergies or allergic reactions.

Though there have been reports of deaths after vaccination, the CDC says it appears there is no link.

The vaccines were first given to long-term care residents over age 65, and it’s known that a certain percentage of individuals in this group will die each month.

It’s expected then that several thousand long-term care facility residents, coincidentally, could die after vaccination.

Now that millions of doses have been administered, researchers are getting a clearer picture of the vaccine reactogenicity, or the body’s inflammatory response to a vaccine.

Dr. Daniel Fagbuyi, an emergency physician who served as a biodefense expert in the Obama administration, says vaccines teach the body to recognize the imposter — the novel coronavirus.

As a result of the body learning how to combat a foreign invader, we might experience some pain or aches.


“It doesn’t mean it’s bad, it means the body is responding and doing what it’s supposed to do — preparing to fight,” Fagbuyi said.

Most commonly, the reactogenicity included pain at the injection site. Fatigue, headache, and chills were also reported, more commonly after the second dose.

“What is assumed is the first dose primes the immune system, letting the immune system experience the vaccine for the first time,” Dr. Henry Bernstein, a pediatrician at Northwell Health’s Cohen Children’s Medical Center and a member of the CDC Advisory Committee on Immunization Practices (ACIP) committee, told Healthline.

“Then the second dose uses the immune system’s memory of that first dose to boost a person’s immunity. This may be why the potential for more side effects occurs,” Bernstein explained.

More than 15,000 vaccinations in pregnant people have been reported to the CDC.

There’s limited data on the safety of administering the vaccine during pregnancy, but it’s generally thought to be safe.

The American College of Obstetrics and Gynecology has recommended the vaccine be offered to pregnant women.

Women should have a conversation with their obstetricians, as the benefits of getting the vaccine may outweigh their risks of contracting COVID-19, according to Bernstein.

“Pregnant people who get COVID are at an increased risk for severe illness, and that’s important for them to recognize,” he said. “That means being admitted to the hospital, getting into an intensive care unit, being put on a ventilator, and even dying.”

There were 50 cases of anaphylaxis reported following the Pfizer vaccine and 21 cases of anaphylaxis linked to the Moderna vaccine.

Most events occurred within 15 minutes of vaccination, with one case occurring 20 hours after vaccination.

More than 80 percent of cases occurred in individuals with a history of allergies or allergic reactions. About a quarter occurred in people with a history of anaphylaxis.

Most cases occurred in women, but it’s unclear why.

“For any vaccine, usually the risk of anaphylaxis is 1 to 2 per million,” Bernstein said. With Pfizer and Moderna, the risk originally appeared to be higher, but as more people are vaccinated, the incidence of anaphylaxis is approaching the 1 to 2 per million range.

“It’s getting closer toward what we would expect or what we have seen in the past with all other vaccines that are given to people,” Bernstein said.

As more people are vaccinated, researchers note the rare, uncommon side effects.

“It’s the law of numbers,” Fagbuyi said. “As the number [of vaccinations] increases, then you’ll pick up the little subtle signals that you wouldn’t pick up in a trial.”

There’s always a risk of anaphylaxis with any vaccine, according to Bernstein, but the benefits typically outweigh the risks.

The locations where vaccines are given should be prepared if any allergic reaction were to occur, Bernstein added.

Though there have been a few deaths reported after vaccinations, among the first to get vaccinated were residents of long-term care facilities.

A percentage of long-term care facility residents will die each month, often due to heart disease or underlying conditions.

According to the CDC report, deaths in this population after vaccination are purely coincidental events. The CDC will continue tracking the safety of the vaccines.

For now, health experts want to increase the number of vaccinations to build population immunity against COVID-19.

“The more people who get it, the more community immunity there will be. And the sooner that we achieve that, the better — particularly with new variants around,” Bernstein said.

A new report from the Centers for Disease Control and Prevention (CDC) based on recent safety surveillance data shows the Pfizer and Moderna vaccines are safe and associated with few serious side effects. People most commonly have experienced mild pain at the injection site, fatigue, and headache. Anaphylaxis is rare and typically occurs in people with a history of allergies. Overall, the vaccine is considered safe, and as more people get vaccinated, the greater population immunity we’ll achieve that’ll help us get a handle on the pandemic.