Tip Sheet: Key Facts About the COVID-19 Vaccine

Since early 2020, people around the world have been coping with COVID-19, the disease caused by the highly infectious SARS-CoV-2 virus that causes mild to severe respiratory illness. Cases of COVID-19 can be mild, but others can be more severe and even deadly—especially for older adults or those living with chronic health conditions. One in 100 older Americans have died from COVID-19 disease, and 75% of all COVID-19 deaths in the United States have been among adults 65 years or older. 

In August 2021 the U.S. Food and Drug Administration (FDA) provided full authorization for the Pfizer-BioNTech vaccine. The FDA has provided emergency authorization for the Moderna and Johnson & Johnson/Janssen (J&J) vaccines. All three vaccines are highly effective against getting severe COVID-19. The federal government is coordinating the distribution of vaccines across states.

Here’s what you need to know about how a vaccine for COVID-19 will help protect you and your loved ones. The summary table below provides information about these three vaccines, with more detailed information following the table.

Approved COVID-19 Vaccines (as of 12/22/2021)
Vaccine Name Initial Dosing Information Booster Doses Doses for Immuno-compromised People Possible Side Effects  
Pfizer-BioNTech 2 doses, 21 days apart

People 18 and older should receive booster doses.

Booster doses should be administered 6 months after receiving the 2nd shot of the initial vaccine series. Pfizer-BioNTech vaccine recipients can receive booster shots from Pfizer-BioNTech, Moderna, or Johnson & Johnson.

Administered at least 28 days after the second dose. Pain, swelling or redness at injection site, fatigue, headache, muscle or joint pain, chills, fever, nausea, swollen lymph nodes. For more information from the Food & Drug Administration (FDA) about this vaccine, visit: https://www.fda.gov/media/144414/download


Moderna 2 doses, 28 days apart

People 18 and older should receive booster doses.

Booster doses should be administered 6 months after receiving the 2nd shot of the initial vaccine. Moderna booster shots are half-doses of the original vaccine dose. Moderna vaccine recipients can receive booster shots from Moderna, Pfizer-BioNTech, or Johnson & Johnson.

Administered at least 28 days after the second dose. Pain, swelling at injection site, fatigue, headache, muscle or joint pain, chills, fever. For more information from the Food & Drug Administration (FDA) about this vaccine, visit: https://www.fda.gov/media/144638/download


Johnson & Johnson/Janssen 1 dose All people who received the Johnson & Johnson/ Janssen vaccine are eligible for a booster dose at least 2 months after the first shot was administered. Johnson & Johnson vaccine recipients can receive booster shots from Johnson & Johnson, Moderna, or Pfizer-BioNTech. No additional primary shot is recommended at this time.

Pain, redness of the skin and swelling at the injection site, headache, fatigue, muscle aches, nausea, fever For more information from the Food & Drug Administration (FDA) about this vaccine, visit: https://www.fda.gov/media/146305/download



*NOTE: The Johnson & Johnson vaccine was “paused” in April 2021 due to a rare side effect, called thrombosis with thrombocytopenia syndrome (TTS). The FDA and CDC evaluated the safety of the vaccine during the pause. They determined that its benefits outweigh its risks.  Additional cases of TTS due to the Johnson & Johnson vaccine have been documented since the pause including 8 deaths.  There were only 2 cases of TTS and no deaths in person 65 years and older.  The FDA added a contraindication that Johnson & Johnson vaccine should not be administered to individuals with a history of thrombosis with thrombocytopenia following the Johnson & Johnson COVID-19 vaccine.  The CDC recommends, in most situations, that the Pfizer-BioNTech or Moderna COVID-19 vaccines are preferred over the Johnson & Johnson COVID-19 vaccine for primary and booster vaccination.

Safety has been key to the development and approval process of COVID-19 vaccines.

Tens of thousands of people have participated in carefully designed and controlled clinical trials of COVID-19 vaccines to determine how safe and effective they are. Once proven safe and effective, the U.S Food and Drug Administration (FDA) and independent, expert advisory boards review the clinical trial data to make sure that the data are correct.

The FDA originally issued an emergency use authorization for all three vaccines. Emergency use authorization is only granted if the benefits of a vaccine outweigh its risks. Under an emergency use authorization, vaccines are still considered investigational. The FDA has now provided full authorization for the Pfizer-BioNTech vaccine. The emergency use authorizations for the Moderna and Johnson & Johnson/Janssen (J&J) vaccines are still in effect while the companies are in the process of applying for full FDA authorization.

In addition, the Advisory Committee on Immunization Practices (ACIP) at the Centers for Disease Control and Prevention (CDC) reviews all safety data before recommending any COVID-19 vaccine for use. All three vaccines have been reviewed for safety and found to be safe and effective.The CDC currently recommends receiving an mRNA vaccine, either the Pfizer or Moderna vaccines due to the severity of safety issues with the Johnson & Johnson vaccine and higher vaccine effectiveness of mRNA vaccines compared with the Johnson & Johnson vaccine. 

The COVID-19 vaccination will help prevent you from getting the virus.

Getting a COVID-19 vaccine will lower your risk of getting sick if you are exposed to the novel coronavirus. It is still possible that you may contract COVID-19 after receiving the vaccine, but data from real-world use of COVID-19 vaccines to date suggests that getting vaccinated may also help you from getting seriously ill if you do get infected. Both the Pfizer-BioNTech and Moderna vaccines require two doses and it is very important to keep your second appointment to receive your second shot. This is how these vaccines were designed, and it’s what makes both most effective. The Johnson & Johnson vaccine only requires one shot.

Consult the FDA fact sheets for recipients and caregivers of the Pfizer-BioNTech, Moderna, and Johnson & Johnson vaccines for more information. We also recommend discussing the risks and benefits of getting vaccinated with your primary healthcare provider.

You may have heard about variants of COVID-19 in the news, including the Delta and Omicron variants. Variants are caused when the COVID-19 virus changes (known as mutation). Different variants may spread more easily, may cause more serious disease, and may not respond as well to treatment. 

Therefore, it is important to continue to take steps to prevent the spread of COVID-19. So far, the COVID-19 vaccines provide protection against the known variants, including Delta and Omicron, and vaccination, including a booster shot, is still the best protection available. However, no vaccine provides 100% protection against COVID-19 and its variants. Therefore, even people who are vaccinated should keep following recommended steps to protect themselves and others. 

The short-term side effects of the COVID-19 vaccination are manageable.

When you get a vaccine, your arm may be sore, red, or warm to the touch, but these symptoms usually go away on their own within a week. In the trials, some people reported getting a headache, muscle aches, fatigue, or fever after getting a vaccine. These symptoms usually went away in a few days. These side effects are a sign that your immune system is doing exactly what it is supposed to do: working and building up protection to disease.

Before getting any vaccine, tell your vaccination provider about all your medical conditions, including if you:

  • Have any allergies
  • Have a fever
  • Have a bleeding disorder or take blood-thinning drugs
  • Are immunocompromised or take medicine that affects your immune system
  • Are pregnant or plan to become pregnant
  • Are breastfeeding
  • Have received another COVID-19 vaccine

They will discuss any additional factors you need to know before receiving a COVID-19 vaccine based on your unique circumstances.

If you have received the Johnson & Johnson vaccine, you should look out for symptoms of blood clots with low platelets for three weeks after your shot. These include:

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

If you experience any of these symptoms after receiving the Johnson and Johnson vaccine, seek medical attention immediately.

Getting vaccinated protects others.

Getting vaccinated yourself may help protect the people you are around, especially those who are at increased risk of becoming seriously ill from COVID-19, including older persons and those with chronic, underlying conditions.

The vaccine is available at no cost to you, whether you have insurance or not.

Any FDA-authorized vaccine is covered under Medicare at no cost to beneficiaries. Medicaid and private health insurance are also required to cover all vaccine costs during this public health emergency, and people who are uninsured can get free vaccines from their state or local health department or a community health center. Updates on the vaccine’s availability in your community are available from your state’s health department.

The COVID-19 vaccines are now available to everyone 12 years and up.  All eligible individuals can now get vaccinated at large chain pharmacies, independent pharmacies, regional chain pharmacies, and federally qualified health centers. See vaccines.gov for more information. You can also text your zip code to 438829 or call 1-800-232-0233 to find COVID-19 vaccine locations

As of December 21, 2021, the CDC reports that over 495 million vaccine doses have been administered.

Even with a vaccine available, it is still important to wear a mask and to physically distance.

Although the vaccines are safe and effective, many people remain unvaccinated, and the COVID-19 virus can still spread. It is very important that we all continue to use all the tools available to us to help stop this pandemic, including wearing a mask over your nose and mouth, washing your hands often, and staying at least 6 feet away from others in public. Getting the COVID-19 vaccination and following the CDC’s recommendations for how to protect yourself and others from getting sick will offer you the best possible protection from getting and spreading COVID-19. 


Last Updated December 2021