If Your Vaccine Side Effects Last This Long, Get a COVID Test, Doctor Says

What seems like a reaction to the vaccine could really be the virus.

There's a chance you'll end up feeling sick after getting the COVID vaccine, which can be a nerve-wracking experience during a pandemic. Fortunately, the Centers for Disease Control and Prevention (CDC) says that experiencing side effects after COVID vaccination is a normal response to your body building immunity, and not any cause for concern. However, if your side effects are sticking around a little longer than you expected, that could indicate that something is amiss. Experts say that if your vaccine side effects last too long, you may need to get tested for COVID—especially since vaccine side effects and COVID symptoms can look quite similar. Read on to find out if you need a COVID test, and for more on vaccine reactions, This Vaccine Side Effect Could Mean You Already Had COVID, New Study Says.

Doctors say you should get a COVID test if your vaccine side effects last longer than 72 hours.

Ill man covered with blanket.

Vaccine side effects are normal, but they should only last a few days, according to the CDC. If they stick around longer, you could actually be experiencing symptoms of COVID. Common side effects of the vaccine—like fatigue, fever, and body aches—are also symptoms that develop if you have the virus. "If your symptoms last longer than 72 hours, it is worth making sure you don't actually have COVID-19," Manisha Juthani, MD, an infectious diseases specialist at Yale Medicine and associate professor at the Yale School of Medicine, told Verywell. And for more on the vaccine, This Is the Only Way to Tell If Your COVID Vaccine Worked, Doctors Say.

If you do have COVID, it's not from the vaccine, however.

A male healthcare worker is holding a syringe and measuring the right amount of vaccine dosage prior to administering the medical injection onto a patient's arm

If you do find out you have COVID after getting the vaccine, it's not because the vaccine gave you COVID, however. As the CDC explains, none of the three COVID vaccines available in the U.S.—Moderna, Pfizer, and Johnson & Johnson—are live vaccines, which means they cannot give you the virus they are protecting against. However, it takes a few weeks after vaccination to build immunity, which means "it is possible that a person could be infected with the virus that causes COVID-19 just before or just after vaccination and then get sick because the vaccine did not have enough time to provide protection," the CDC says. And for more guidance from the CDC, The CDC Says Don't Do This Within 2 Weeks of Your COVID Vaccine.

You should wait to get the second shot if you catch COVID in-between doses.

woman having a nasal swab test for Covid-19

The CDC says you should not get the vaccine if you are currently infected with COVID. So if you do get the coronavirus in-between the first and second dose of Pfizer or Moderna, you should postpone your second shot. "Vaccination of people with known current SARS-CoV-2 infection should be deferred until the person has recovered from the acute illness (if the person had symptoms) and they have met criteria to discontinue isolation," the CDC says.

If you do need to delay your second dose, the agency says it can still be administered up to six weeks after the first dose. However, if you are just experiencing side effects after the first shot and not the virus, you should still get your second shot on time "unless a vaccination provider or your doctor tells you not to get it," the CDC says. And for more useful information delivered straight to your inbox, sign up for our daily newsletter.

There is a small chance you could get infected with COVID once fully vaccinated.

Full length shot of a young man sitting on his bed while feeling unwell at home

You are considered fully vaccinated by the CDC once it has been two weeks after your second shot in a two-dose series or two weeks after a single-shot vaccine. While this means that you are protected against COVID, the CDC says there is a small chance you could get infected with the virus after vaccination. "A small percentage of people fully vaccinated against COVID-19 will still develop COVID-19 illness," the agency explains. "While these vaccines are effective, no vaccine prevents illness 100 percent of the time. For any vaccines, there are breakthrough cases."

With that in mind, if you are fully vaccinated and experiencing any symptoms of COVID—fever, chills, cough, shortness of breath, difficulty breathing, fatigue, muscle or body aches, headache, new loss of taste or smell, sore throat, congestion, runny nose, nausea, vomiting, or diarrhea—you should get tested for the virus just in case. And for more coronavirus news, COVID Leaves This in Your Body Even If You're Asymptomatic, New Study Says.

Best Life is constantly monitoring the latest news as it relates to COVID-19 in order to keep you healthy, safe, and informed. Here are the answers to your most burning questions, the ways you can stay safe and healthy, the facts you need to know, the risks you should avoid, the myths you need to ignore,and the symptoms to be aware of. Click here for all of our COVID-19 coverage, and sign up for our newsletter to stay up to date.
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