Should you worry about side effects of COVID-19 vaccines?

SAN JOSE, Calif. – A day after injection with the new COVID-19 vaccine, Tricia Potocki felt one major side effect: relief.

A respiratory therapist at John Muir Health at high risk of viral exposure, she decorated her Danville house for the holidays after returning home Wednesday from receiving her shot. On Thursday, she worked out on her elliptical trainer.

“I feel perfectly normal,” said Ms. Potocki, who for months has worried about accidentally infecting her husband, who is older and medically vulnerable. “I see the end of this long, dark tunnel. I’m so happy.”

As the first vaccines from Pfizer Inc. and Moderna roll out, scientists say minor side effects, such as fever, are a welcome sign that the vaccine is working. There are only isolated reports of adverse events among people who have had shots.

In Alaska, a Juneau health care worker was hospitalized and treated for a serious allergic reaction after receiving the Pfizer vaccine. At the same hospital, another worker developed puffy eyes, light headedness and a scratchy throat. Those followed reports that two British health care workers had a severe allergic reaction, called anaphylaxis, after receiving the vaccine.

On Thursday, a U.S. Food and Drug Administration advisory panel endorsed the Moderna vaccine, saying the benefits far outweigh the risks. Californians will receive about 1.8 million doses of the Pfizer and Moderna vaccines this month. Of those, 1.7 million doses will be given to health care workers, and 640,000 doses will be given to residents of nursing homes.

Of the tens of thousands of Americans who have already received the vaccines in clinical trials, none have reported any lifethreatening health problems.

Much more common, say experts, are feelings of fatigue, headache, muscle soreness and warmth or swelling around the site of the injection. At an FDA meeting last week, a federal medical officer reported that three people developed facial or lip swelling after vaccination with the Moderna vaccine that may have been linked to prior cosmetic injections of dermal fillers. Cases of Bell’s palsy, a temporary facial paralysis, were reported in both the Pfizer and Moderna trials.

The symptoms are evidence of the body mounting a strong immune response to the vaccine, said Dr. Barry Bloom, a professor of immunology and infectious diseases at the Harvard T.H. Chan School of Public Health.

“A reaction at the site of injection is a good thing, reflecting an immediate response to a foreign material that will ultimately enhance the immune response,” he said.

The Moderna data shows that after the second of two doses, about twice as many trial volunteers experienced side effects compared with those injected with a placebo. Pfizer’s vaccine, which uses mRNA technology similar to Moderna’s, showed similar side effects. Volunteers in both trials who received the vaccine also reported pain at the injection site more frequently than placebo recipients.

To be safe, vaccine recipients are retained for up to a half hour at injection sites to monitor for signs of an adverse reaction. These sites have medications on hand to quickly reverse any unexpected allergic reaction.

Jeff Orum, of Sunnyvale, a retired high-tech worker, developed a sore arm but no other symptoms after getting vaccinated with Pfizer vaccine earlier this year as part of its Phase 3 trial. Like the other 41,100 volunteers who took part in Phase 3 clinical trials for the company’s vaccine, he wasn’t told whether he got the vaccine or a placebo.

“I’d describe it as a dull ache, nothing major” that lasted about two days and was less painful than the Shingles vaccine, he said.

The side effects last about a day and appear more likely after the second dose. After her first injection with the Pfizer vaccine during the Phase 3 trial, UCLA assistant professor of nursing Kristen Choi noticed only minor soreness in her arm. But after her second injection a month later, her arm was much more painful. Over the course of

the next 24 hours, she experienced a range of symptoms, including high fever, dizziness, nausea and a headache. Aside from a bump on her arm where the injection had been, all of the symptoms went away after a day.

Bay Area hospitals are staggering vaccinations in case some front-line workers feel sick and need to take a day off from work.

“We ‘randomize’ vaccine distribution so we don’t put the emergency room or the ICU out of business overnight,” said Dr. Susan Smith, chief faculty practice officer at the University of California, San Francisco.

Experts worry that reports about side effects could become a reason people optout of vaccination. In general, Americans have grown more confident that the development process will deliver a safe and effective vaccine. In early December, a Pew Research Center poll found that about 60% of Americans would be willing to take the shot, up from 51% in September. Among those who said they would not or probably would not take the vaccine, 76% said concern about the side effects was a primary reason.

Nathaniel Riley is a transport tech whose job involves moving patients — including those with COVID-19 — between different areas of Stanford Medical Center. That puts Mr. Riley, 43, near the front of the line for the vaccine, along with doctors and nurses. Still, he said he wants to wait a few weeks to learn more about the side effects, despite his high-risk job and losing two aunts to the disease.

“I’m glad that they found the vaccine,” he said. “Because it’s just coming out, I’d rather look more into it.”

During the next several months, it is inevitable that there will be tales of suffering and death as more Americans are vaccinated, warn experts. But this won’t be the fault of the vaccine.

During a typical twomonth period, pandemic or no pandemic, 14,000 Americans will die, according to Dr. Robert Wachter, chair of UCSF’s Department of Medicine. Another 4,025 Americans will have a heart attack, 3,975 will have a stroke, 9,500 will get a new cancer diagnosis, and 60 will be diagnosed with multiple sclerosis.

A sore arm was a small price to pay for helping make history, said Mr. Orum.

“It felt good to be part of the study,” he said.