COVID-19 (Coronavirus)

The coronavirus disease 2019 (COVID-19) pandemic disrupted our lives and our healthcare systems and accounted for millions of illnesses across the globe ranging from mild to severe to deadly. COVID-19 vaccination is a critical tool in stopping this pandemic.

There are several COVID-19 vaccines that are in the late stages of development. Currently, three vaccines have been authorized for use by the U.S. Food and Drug Administration (FDA) and recommended by the Centers for Disease Control and Prevention (CDC). These vaccines are designed to teach your body’s immune system to recognize and fight off the virus that causes COVID-19. There are several COVID-19 vaccines that are in the late stages of development and may be authorized for use in the future.

Millions of people in the United States have received COVID-19 vaccines. These vaccines have undergone the most intensive safety monitoring in U.S. history and were found to be both safe and effective. Two of these vaccines require two doses. The first shot starts building protection. A second shot a few weeks later is needed to get the most protection the vaccine has to offer. The vaccine that only requires one dose has been paused for use out of an abundance of caution until the CDC and FDA can review data to assess a potential safety issue involving six people reported a rare and severe type of blood clot after getting this vaccine.

None of these vaccines will give you COVID-19.

Information about COVID-19 vaccines will be updated frequently as new information becomes available.

CDC will convene a meeting of the Advisory Committee on Immunization Practices (ACIP) on Wednesday to further review these cases and assess their potential significance. FDA will review that analysis as it also investigates these cases. Until that process is complete, we are recommending a pause in the use of this vaccine out of an abundance of caution. This is important, in part, to ensure that the health care provider community is aware of the potential for these adverse events and can plan for proper recognition and management due to the unique treatment required with this type of blood clot.

Why are COVID-19 vaccines important?

COVID-19 has sickened and killed millions of people worldwide. COVID-19 vaccines have been tested in clinical trials to determine that they are highly effective in stimulating our bodies to develop immunity and protect us from the disease. Therefore, COVID-19 vaccines are a critical tool in stopping the pandemic, resuming normal life, and protecting ourselves and others from this disease.

What is COVID-19?

COVID-19 is caused by a virus called Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). It is caused by a strain of coronavirus not previously seen in humans. Coronaviruses, named for the crown-like spikes on their surfaces, are a large family of viruses, which circulate in humans and other animals such as pigs, bats, and cats.

SARS-CoV-2 is the third novel coronavirus to emerge in this century and infect humans (the original SARS outbreak emerged in China in 2003 and the Middle East Respiratory Syndrome Coronavirus emerged in Saudi Arabia in 2012). It was first reported in Wuhan, China, in December 2019. COVID-19 was declared a global pandemic by the World Health Organization in March 2020. The United States declared a public health emergency for the COVID-19 pandemic in March 2020 as well.

SARS-CoV-2 spreads easily from person-to-person when people are in close contact, mainly through respiratory droplets produced when an infected person coughs, sneezes, or talks. To a less extent, the virus can also spread by people who touch contaminated surfaces or objects such as handrails and doorknobs, then touching their eyes, noses, or mouths without washing their hands first.

People with COVID-19 may not know that they are spreading it. People who are infected with the virus that causes COVID-19 can spread it before they become ill. Some people who are infected might not exhibit symptoms, but can spread the virus to other people. COVID-19 can be serious, especially for older adults and people who have underlying medical conditions like heart or lung disease or diabetes. Symptoms can start in as little as 2 days or as long as 14 days after exposure with the average time taking about 5 days.

Symptoms of COVID-19 include:

Fever or chills
Cough
Fatigue
Loss of taste or smell
Difficulty breathing
Muscle or body aches
Headache
Pain or pressure in the chest
Sore throat
Congestion or runny nose
Nausea or vomiting
Diarrhea
Not able to wake up or stay awake

People with COVID-19 symptoms often recover on their own. They can also slowly get worse with difficulty breathing, or abruptly become very ill about a week after their symptoms start.

Learn more about COVID-19.

Who should get COVID-19 vaccines?

Not everyone will be able to get a COVID-19 vaccine right away. When more COVID-19 vaccines are available, more people will be able to get them. Each state decides who is eligible to get these vaccines. The FDA authorized the Pfizer-BioNTech COVID-19 vaccine for individuals 16 years of age and older, and the Moderna and Janssen COVID-19 vaccines for individuals 18 years of age and older. Please note that the use of Janssen COVID-19 vaccine has been paused out of an abundance of caution until the CDC and FDA can review data to assess a potential safety issue involving six people reported a rare and severe type of blood clot after getting this vaccine.

Who should not get COVID-19 vaccines?

You should not get a coronavirus vaccine if you:

Had a severe allergic reaction to any ingredient in the vaccine (you can find vaccine ingredients on the Janssen, Moderna and Pfizer fact sheets)
Had a severe reaction after a previous dose of the Moderna or Pfizer vaccine

You should talk with your healthcare provider before getting vaccinated if you:

Are sick, not feeling well, or have a fever
Think you may have had a serious reaction to a vaccine in the past
Have allergies
Have a bleeding disorder or are on a blood thinner
Are immunocompromised or are taking medicine that affects your immune system
Are planning to become pregnant, are pregnant, or are breastfeeding
Have received another COVID-19 vaccine

What are the side effects of COVID-19 vaccines?

These COVID-19 vaccines were tested for safety and will continue to be studied to ensure their safety. Most people who have taken COVID-19 vaccines report that side effects are usually mild and go away after several days. However, it is possible for severe and unexpected side effects to occur.

The common side effects may include:

Pain, swelling, or redness where the shot was given
Feeling tired
Headache
Muscle pain
Chills
Joint pain
Fever
Nausea or vomiting
Feeling unwell
Tender or swollen lymph nodes

Experiencing these side effects actually means that the vaccine is working to stimulate your body to generate an immune response. Remember, vaccines mimic a natural infection without causing us to become sick. Some people feel their immune response more than others and some people may feel the immune response more after the second dose of the vaccine. Learn more about vaccine side effects.

There is a remote chance that a COVID-19 vaccine could cause a severe allergic reaction. A severe allergic reaction would usually occur within a few minutes to one hour after getting a dose of a COVID-19 vaccine. For this reason, your vaccination provider may ask you to stay at the place where you received your vaccine for monitoring after vaccination.

Signs of a severe allergic reaction can include:

Difficulty breathing
Swelling of your face and throat
A fast heartbeat
A bad rash all over your body
Dizziness and weakness

If you experience a severe allergic reaction, call 9-1-1, or go to the nearest hospital. Call your vaccination provider or your healthcare provider if you have any side effects that bother you or do not go away.

Please report any potential side effects experienced from COVID-19 vaccination to the Vaccine Adverse Event Reporting System, a program co-managed by the U.S. Centers for Disease Control and Prevention and the Food and Drug Administration to ensure that all recommended vaccines remain safe. The Countermeasure Injury Compensation Program (CICP) may help pay for the costs of medical care and other expenses for people seriously injured from a COVID-19 vaccine. Learn more about the CICP.

These may not be all the possible side effects of a COVID-19 vaccine. Serious and unexpected side effects may occur, as these vaccines are still being studied in clinical trials.

How is COVID-19 vaccine safety being monitored for safety?

A robust vaccine safety monitoring system is in place in the United States for COVID-19 and other vaccines. Learn how our federal partners are working together to ensure the safety of COVID-19 vaccines, which includes developing new safety monitoring systems and additional information sources. All COVID-19 vaccines authorized for use underwent clinical trials in many thousands of study participants, and will continue to be monitored and studied to ensure their safety. Data from these activities are monitored by CDC, FDA and other federal agencies. You can read the statement FDA and CDC released regarding the pause of the Janssen COVID-19 vaccine.

After vaccination, you can sign up for a new health check service on your smartphone, called V-safe from the Centers for Disease Control and Prevention. V-safe uses text messaging and web surveys to check in with vaccine recipients after COVID-19 vaccination. V-safe also provides a reminder to get your second dose of vaccine, if needed, and will follow up with you if you report a medically important event.

Where can I get more information about COVID-19 vaccines?

LAST REVIEWED: March 2021