Mild vaccine side effects are ‘absolutely normal’ and no reason to avoid COVID shots, doctors say

The pain in Timothy Smith’s left arm had gotten worse - “It felt like somebody had bashed my arm for a solid hour,” he said - and fatigue was starting to set in, but the 34-year-old who describes himself as “pretty all-around healthy” wasn’t panicked. About a day earlier on Oct. 7, Smith had gone in for his first injection in Moderna’s novel coronavirus vaccine trial. And because he had done research beforehand and was prepped by the clinical team, Smith said he felt equipped to handle any of the vaccine’s reported side effects, which experts say are signs that the body’s immune system is working.

“I was never in the dark about any of the process,” said Smith, a former Washington Post staffer who is now a union organizer in the District. “I think sometimes if people don’t know what to expect that can make you a little more fearful, and they were good about laying out everything that could potentially happen.” He wasn’t told whether he was given the vaccine or a placebo, but he believes he was given the vaccine based on his reaction to the injections.

Ahead of the anticipated distribution of Moderna’s two-dose vaccine and a similar vaccine developed by Pfizer and German biotechnology company BioNTech, which could be coming in a matter of weeks, experts have stressed the importance of transparent messaging in ensuring wide public acceptance and completion of the vaccination regimens. Though a full detailed analysis of the safety profile of the vaccines is forthcoming and will be a topic of discussion at the Food and Drug Administration’s advisory committee meetings this month, the drugmakers’ disclosures about the possible side effects coupled with anecdotal reports from trial participants have prompted concern among some experts that people may be hesitant to get vaccinated or won’t come back for their second dose.

“We talk about these vaccines as being reactogenic, which is just a big word that means the way they work, you will feel that they’re working,” said Kelly Moore of the Immunization Action Coalition, who is also an external adviser for Pfizer’s vaccine effort. “So, it will give a reaction, and that reaction may be a sore arm or some redness where the injection was given. Or you may even feel flu-like, you may have a headache or body aches for a day or so, and it’s absolutely normal. There’s nothing dangerous or bad about these reactions.”

But if people aren’t properly informed, Moore and other experts anticipate that the vaccine rollouts “could indeed go very poorly.” A Pew Research Center survey conducted in September indicated that Americans are split on whether they will get vaccinated: 51% said they would “definitely or probably” get the COVID vaccine if it were available today, and 49% said they would not. Among those who said they would not, many cited concerns about side effects and uncertainty around effectiveness, according to Pew.

“If we sugarcoat it, that’s going to backfire because they’re going to get the vaccine, they’re going to feel bad, and then they’re going to say, ‘That vaccine made me sick,’ " said Melanie Swift, an occupational medicine doctor helping to lead COVID vaccination efforts at the Mayo Clinic. Swift noted that some people have been deterred from getting flu shots because of potential side effects, which are often mild. “This is going to be more significant,” she said.

Former FDA commissioner Mark McClellan added that the COVID vaccines are “likely to be more unpleasant than a flu vaccine.”


“But, on average, COVID-19 is a lot worse than the flu,” McClellan said.

Moderna has disclosed some reports among trial participants of “severe” side effects, or those that could impede daily activity, according to a November news release. Significant side effects from the first dose included injection site pain, but more felt worse after the second shot - reporting fatigue, muscle and joint pain, and headache, among other symptoms. In the Pfizer trial, participants reported fatigue and headaches after getting the second dose. Both drugmakers said their vaccines were “well-tolerated,” safe and effective, and that most of the side effects resolved shortly after the shots were administered.

Smith said his symptoms cleared up about three days after he got each shot.

Susan Lakes, a participant in the Pfizer trial who felt fatigued, achey and nauseated after her second shot, said she was back to normal in even less time.

“It just came real fast and it went real fast,” said Lakes, 66 of Cincinnati, whose side effects were gone within 24 hours.

The key to reassuring the public lies in proper messaging, said William Moss, executive director of the International Vaccine Access Center at the Johns Hopkins Bloomberg School of Public Health. The 2 to 10% of participants reporting reactions in the trials would translate to a lot more people once millions are getting vaccinated, Moss said.

“We’re behind on the communications,” he said, partly because the process of developing these vaccines has gone so quickly and much of the trial data has not been made public yet. He added: “It’s kind of the surprise and the unknown that creates the fear and perhaps leads to a decision - I hope this doesn’t happen - not to get the second dose.”

Getting both doses of the COVID vaccines is critical, experts said. The first shot acts as a priming dose for the immune system and is not believed to offer much protection on its own.

Kelly pointed to the role transparency played in the success of the shingles vaccine, Shingrix, which is also a two-dose series and can cause reactions similar to the COVID vaccines. Initially, there was concern that people would not return for their second shot, but “it turns out that pharmacists and doctors did a great job of telling people what to expect,” Kelly said, noting that 75 to 80% of people have gotten their second doses on time.

“We underestimated the motivation of the public to protect themselves from shingles, and my hope is that if we prepare the public appropriately, they will be very motivated to protect themselves from COVID-19,” she said.

Swift urged people to allow for time to recover from any side effects when scheduling their vaccinations. Maybe plan to take a day off and stock up on Tylenol or Advil, Moss said.

Clear and straightforward messaging about the vaccines needs to start with promoting confidence among health-care workers, who are going to be among the first to receive the injections, said Sean O’Leary, vice chair of the Committee on Infectious Diseases for the American Academy of Pediatrics. Kelly added that research has shown people’s decisions about vaccinations are “most heavily influenced” by the providers they engage with on a regular basis.

When communicating with patients who are worried about the vaccines, O’Leary recommended that providers prioritize having “a nuanced conversation where you just have to listen carefully to what their concerns are and respond thoughtfully.”

It may be beneficial for providers to use “motivational interviewing techniques,” such as asking if they can share what they have learned about the vaccines with the patient, said O’Leary, who has done work in vaccine communication.

“A lot of times in these conversations, if someone comes in with resistance, it’s very easy to get in an argument,” he said. “The important thing is really avoiding that argument and really trying to make it a productive conversation.”

Some experts have already launched large-scale efforts to reach people, including those in marginalized communities, who may have concerns about COVID vaccines. The National Medical Association, the largest and oldest group of Black physicians in the country, has assembled a task force and is working with health-care groups, community organizations and medical schools, among others, to spread information about the pandemic and vaccines. A recent survey focusing on Black and Latino communities found that 14% of Black people trust that a vaccine will be safe, and 18% trust that it will be effective in protecting them from the coronavirus. (The survey was conducted before the release of interim analyses, which had promising data on the efficacy and safety of vaccines from Pfizer and Moderna.)

“We’re building coalitions with trusted messengers in the Black community,” said Leon McDougle, president of the association. He later added, “We hope to break down barriers to not only access and distribution of the COVID-19 vaccines shown to be safe and effective, but also uptake in the Black community.”


In the meantime, though, Swift said experts and the public “have to keep our eye on the prize.” People are “tough enough to get through” the potential reactions caused by the vaccines, she said, “and it’s worth it to do it.”

“This is our light at the end of the tunnel,” she said, adding, “This is not a simple vaccine, but it is an effective vaccine, and what about 2020 has been simple so far?”

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The Washington Post’s Laurie McGinley, Carolyn Y. Johnson and Frances Stead Sellers contributed to this report.