Getting a Lifesaving COVID-19 Vaccination

Expect some mild side effects

No serious side effects were reported in clinical trials, but you may feel under the weather for a few days after you get the shot, says William Schaffner, M.D., an infectious disease specialist at Vanderbilt University Medical Center in Nashville, Tennessee, and medical director of the National Foundation for Infectious Diseases.

In addition to a sore arm, reported side effects include tiredness, headache, muscle pain, joint pain, chills, fever, nausea, swollen lymph nodes and a delayed rash or swelling at the injection site.

“These are not COVID,” Schaffner says, noting that there is no COVID-19 virus in any of the vaccines. “It’s your immune system responding. It’s a small price to pay for what looks to be very solid protection.”

Side effects are less common in patients 55 and older, according to the CDC, and they occur more frequently after the second dose. To play it safe, Schaffner recommends not making any big plans for the few days after you get a dose of the vaccine.

If you have a history of severe allergic reactions, also known as anaphylaxis, talk to your doctor before you get the vaccine, advises Robert Finberg, M.D., an infectious disease specialist at UMass Medical School and a member of Massachusetts’ COVID-19 Vaccine Advisory Group.

Which vaccine should you get?

The CDC does not recommend one shot over another. All three vaccines are free for all people living in the United States, regardless of their immigration or health insurance status, and widely available at doctors’ offices, retail pharmacies and hospitals. To find a location near you, go to Vaccines.gov, text your zip code to 438829, or call 800-232-0233.

The Pfizer-BioNTech and Moderna vaccines both use a technology known as mRNA to deliver a small fragment of genetic code to your cells to encourage your body to produce antibodies. The J&J vaccine works differently. It uses a harmless virus that can no longer replicate, called an adenovirus, to send a genetic message to your cells.

There are also practical differences. The biggest one, of course, is that the J&J vaccine requires only one shot.

A CDC study published in August 2021 found that all three vaccines are highly protective for older adults. The Pfizer-BioNTech and Moderna vaccines were 96 percent effective in preventing hospitalization in adults ages 65 to 74 years, the study showed, and the J&J vaccine was 84 percent effective. Among those age 75-plus, efficacy rates were still 91 percent for Pfizer-BioNTech, 96 percent for Moderna and 85 percent for J&J.

If you are getting one of the two-dose vaccines, your second dose should come from the same manufacturer as the first, the CDC says. The Pfizer vaccine is designed to be given in two injections 21 days apart, while the Moderna vaccine calls for a 28-day window between shots.

If you miss your second dose or you don’t get it on time, just get it as soon as you can, Schaffner advises. While you get some immunity from the first injection, it increases dramatically with the second one.

You will still need to wear a mask

Even after you are vaccinated, health officials say you should continue to wear a mask in public indoor settings if you live in an area of substantial or high COVID-19 transmission. (You can check the CDC’s website for a county-by-county look at transmission rates to see if the new guidelines apply to you.)

There’s a chance you could get infected even after you’ve been vaccinated and spread the virus to others, even if you develop mild symptoms or have no symptoms at all. Wearing a mask and keeping your distance are the best ways to protect the people around you and slow the spread of the disease, says CDC Director Rochelle Walensky, M.D.

“Wearing a mask in public, indoor settings and continuing to practice the prevention strategies we know work are important to prevent further increases in cases and hospitalizations, especially for those children too young for the currently available vaccines,” Walensky said.

Editor’s note: This story, originally published on Dec. 29, 2020, was updated in September 2021 with new information. Rachel Nania contributed.