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COVID-19 Vaccine Side Effects: Here’s What to Expect, According to the CDC

Some side effects are totally normal.
COVID19 vaccine side effects.
Heather Hazzan. Wardrobe styling by Ronald Burton; prop styling by Campbell Pearson; hair by Hide Suzuki; makeup by Deanna Melluso at See Management. Shot on location at One Medical.

Now that the first COVID-19 vaccine shipments are making their way across the U.S., you may be wondering whether the COVID-19 vaccine has any side effects. Although the vaccine can cause some temporary flulike side effects, they are generally not serious.

Currently only one COVID-19 vaccine, developed by Pfizer and BioNTech, has received emergency use authorization from the Food and Drug Administration (FDA). Another vaccine, developed by Moderna, is also expected to be authorized soon. Both of these vaccines rely on mRNA technology to create an immune response in the human body that provides significant protection against symptomatic COVID-19 infections.

It's not clear yet whether or not these vaccines also provide protection against asymptomatic infections or whether they prevent transmission of the virus. But having a vaccine that effectively reduces the chances someone will need to be hospitalized or die due to COVID-19 is a big deal on its own.

Like basically all vaccines, a COVID-19 vaccine can cause side effects. These side effects are “normal signs that your body is building protection,” the Centers for Disease Control and Prevention (CDC) says. “These side effects may affect your ability to do daily activities, but they should go away in a few days.”

According to the CDC, the most common side effects associated with a COVID-19 vaccine are:

  • Pain at the injection site

  • Swelling at the injection site

  • Fever

  • Chills

  • Tiredness

  • Headache

Looking at data for about 2,300 clinical trial participants who received the vaccine and another 2,300 who received a placebo, side effects were more common after the second dose of the vaccine than after the first, according to the official prescribing information. Within seven days of getting the second dose, 78% of those participants who received the vaccine experienced pain at the injection site, 59% experienced fatigue, 52% had a headache, 35% reported chills, 16% reported a fever, and 6% experienced redness at the injection site.

These side effects may make you feel like you have the flu and could even affect your ability to go about your daily life for a few days. But it's important to remember that the Pfizer-BioNTech and Moderna vaccines don't contain the live virus, so these are not signs that you're actually sick with a coronavirus infection. (And even vaccines that contain live viruses won't get you sick unless you're immunocompromised.) If you do experience these side effects after getting a COVID-19 vaccine, you may be able to use common over-the-counter pain-relieving medications (like ibuprofen or acetaminophen) to alleviate those symptoms depending on what your doctor recommends, the CDC says.

There are also some reports of more serious side effects after getting the vaccine, specifically severe allergic reactions (anaphylaxis). That's why people who have had an allergic reaction to any component of the Pfizer-BioNTech vaccine should not get it, according to the emergency use authorization.

And people who have had an allergic reaction to any vaccine in the past should discuss whether or not they should get this particular vaccine with their doctor beforehand, the CDC says, and balance the unknown risk for a possible reaction with the potential benefits of getting vaccinated. If they do decide to receive the vaccine, their doctor should monitor them for 30 minutes afterward just in case they do have a reaction.

The authorization and distribution of COVID-19 vaccines is a huge milestone and signals that we may soon be able to significantly reduce the toll of this pandemic. But it's important to be aware that vaccines, like all medications and therapies, can come with some temporary side effects. That alone is not a reason to skip the vaccine, but it is a reason to prepare ahead of time and, possibly, have a chat with your doctor about what to expect.

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