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 occasionally deadly—especially for older adults or those living with chronic health conditions.

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 9/28/2021)
Vaccine Name Vaccine Effectiveness* Initial Dosing Information Booster Doses  Doses for Immuno-compromised People Possible Side Effects
Pfizer-BioNTech 94% 2 doses, 21 days apart

The following groups should receive a booster shot:

The following groups may receive a booster shot based on their individual benefits and risks:

  • people aged 18–49 years with underlying medical conditions
  • people aged 18-64 years who are at increased risk for COVID-19 exposure and transmission because of occupational or institutional setting 
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 94% 2 doses, 28 days apart People who received the Moderna vaccine will likely need a booster dose, but there is not enough data available yet to start the plan for administering boosters. 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 66% 1 dose People who received the Johnson & Johnson/Janssen vaccine will likely need a booster dose, but there is not enough data available yet to start the plan for administering boosters. There is not enough data available yet to determine whether an additional dose of the Johnson & Johnson /Janssen vaccine provides improved protection against COVID-19.

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 the vaccine is still safe and effective, and that its benefits outweigh its risks.

* Vaccines have two roles in protecting you. The first is preventing you from contracting COVID-19 at all. This is the rate reported in this table. The second role of the vaccine in protecting you is how well it prevents you from getting seriously ill or dying if you do get COVID-19. All three of the vaccines have been found highly effective in preventing COVID-19–related hospitalization and death.

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 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 most recent one, the Delta variant. 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 protect against the known variants and vaccination 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.

The Centers for Medicare and Medicaid Services (CMS) announced that 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.

As of September 28, 2021, the CDC reports that over 390 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 September 2021