Many people are wondering if they need an additional shot of the COVID-19 vaccine. Learn more about COVID-19 vaccine booster shots.

Disclaimer: At UPMC HealthBeat, we strive to provide the most up-to-date facts in our stories when we publish them. We also make updates to our content as information changes. However, education about COVID-19 can shift quickly based on new data, emerging variants, or other factors. The information in this story was accurate as of its publish date. We also encourage you to visit other reliable websites for updated information, including the Centers for Disease Control and Prevention (CDC), Food and Drug Administration (FDA), and your state and local governments. 

Millions of Americans have received COVID-19 vaccines developed by Pfizer-BioNTech, Moderna, Johnson & Johnson/Janssen (J&J), and Novavax. Americans 6 months and older are eligible for the vaccine as of June 2022.

The Pfizer, Moderna, and Novavax vaccines require multiple doses to be fully effective. The J&J vaccine currently requires one dose.

You may be familiar with other vaccines. However, you should follow certain steps after receiving the COVID-19 vaccine.

Does the COVID-19 Vaccine Have Side Effects?

Reported data from the vaccines’ clinical trials show they are safe and effective. Serious side effects are rare.

When you receive the vaccine, you will be monitored for an allergic reaction for 15 to 30 minutes after injection. Allergic reactions to the vaccine are rare.

The most common side effects to the vaccine include:

  • Injection site pain/redness/swelling.
  • Arm soreness.
  • Fatigue.
  • Fever or feverishness.
  • Chills.
  • Body/joint/muscle aches.
  • Headaches.

If you have side effects, you can use ibuprofen or acetaminophen as recommended by your care provider. If you have a sore arm, apply an ice pack to ease the discomfort.

According to the Centers for Disease Control and Prevention (CDC), you should contact your doctor if pain or redness at the injection site increases after 24 hours. You should also contact your doctor if your symptoms aren’t going away after a few days.

In rare cases, some people who received the J&J vaccine developed a rare, serious blood clot. The FDA and CDC temporarily paused the distribution of the vaccine to investigate the blood clot cases.

After investigation, the FDA and CDC determined the vaccine’s benefits in preventing COVID-19 outweigh its risks in people 18 and older. These adverse effects are extremely rare.

The J&J vaccine is safe and effective in preventing COVID-19. If you or a loved one receives the J&J vaccine, you DO NOT have to take any medications to prevent blood clots. Call your doctor if you experience side effects related to blood clots, including:

  • Shortness of breath.
  • Chest pain.
  • Leg swelling.
  • Persistent abdominal pain.
  • Severe headaches or blurred vision.
  • Easy bruising or tiny blood spots under your skin, beyond the injection site.

The reported adverse effects associated with the J&J vaccine have not been linked to the Moderna or Pfizer vaccines.

“Most people, regardless of the vaccine they receive, should not expect severe side effects like this,” says Donald Yealy, MD, chief medical officer, UPMC. “It’s exceptionally rare.”

The CDC is monitoring reports of the heart conditions myocarditis and pericarditis in people who received the Moderna and Pfizer vaccines, especially adolescents and young adults. The Novavax vaccine also has been linked to these conditions.

According to the CDC, the reported cases were rare and happened mostly in male adolescents and young adults 16 and older. Symptoms usually presented within days of vaccination, and patients typically responded well to rest and medications.

The CDC continues to recommend vaccination for Americans 6 months and older.

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Do You Still Need to Wear a Mask After Getting the COVID-19 Vaccine?

Like any vaccine, it takes time for your body to build up protection after vaccination. The Moderna, Pfizer, and Novavax vaccines’ full potency doesn’t take effect until after the second dose.

The vaccines are effective in preventing COVID-19, especially in preventing severe illnesses, hospitalizations, and deaths.

It is still possible to get COVID-19 after being vaccinated.

Once you are fully vaccinated, you can resume many activities without wearing a mask or physically distancing, according to the CDC. You should continue to follow existing laws or regulations about masking, including business guidelines.

You are considered fully vaccinated if at least two weeks have passed since you received the second dose of the two-dose vaccines, or if at least two weeks have passed since you received the J&J vaccine.

There are still some situations where you may want to consider wearing a mask, even if fully vaccinated. This may include travel, or when in indoor public places — especially in areas with high levels of community spread.

When Do I Get the Second Dose of the COVID-19 Vaccine?

The time period for when you get your second dose varies depending on which vaccine you received and how old you are. When you get your first dose of the Pfizer or Moderna vaccine, talk to your health provider about scheduling the second dose.

Depending on your age, you also may be eligible for additional or booster doses after your primary series. For more information, visit the CDC website.

Where Can I Go for COVID-19 Vaccine Information?

For information about COVID-19 vaccination at UPMC, visit

Use the CDC’s “v-safe” smartphone tool to report side effects or other concerns to the CDC; someone may contact you for more information. The tool also will remind you to get the second dose of the vaccine. Visit to register.

Editor's Note: This article was originally published on , and was last reviewed on .

Centers for Disease Control and Prevention, What to Expect After Getting a COVID-19 Vaccine. Link

About UPMC

Headquartered in Pittsburgh, UPMC is a world-renowned health care provider and insurer. We operate 40 hospitals and 800 doctors’ offices and outpatient centers, with locations throughout Pennsylvania, Maryland, New York, West Virginia, and internationally. We employ 4,900 physicians, and we are leaders in clinical care, groundbreaking research, and treatment breakthroughs. U.S. News & World Report consistently ranks UPMC Presbyterian Shadyside as one of the nation’s best hospitals in many specialties and ranks UPMC Children’s Hospital of Pittsburgh on its Honor Roll of America’s Best Children’s Hospitals. We are dedicated to providing Life Changing Medicine to our communities.