COVID-19: Learn the Facts

You Stop the Spread, adult on a laptopThe COVID-19 vaccines are safe, effective, free, and widely available. You do not need an ID or insurance to get the vaccine. Visit this page regularly to find the latest, evidence-based information about COVID-19 vaccines, vaccine development, and more.

Information on available vaccines

There are currently three COVID-19 vaccines available in the United States: the Pfizer vaccine, the Moderna vaccine, and the Johnson & Johnson (Janssen) vaccine. Other COVID-19 vaccines are in development.

Here’s what’s important to know: All three FDA-approved vaccines are safe and have been proven to be extremely effective at preventing serious illness, hospitalization, and COVID-19 related deaths. Getting vaccinated is the most effective way to protect yourself and your family from the risks of COVID-19.


Authorized for individuals ages 12 and up.
Type: mRNA
Dose: 2 doses 21 days apart
Efficacy: Based on evidence from clinical trials, the Pfizer-BioNTech vaccine was 95% effective at preventing laboratory-confirmed COVID-19 illness in people without evidence of previous infection.
Source: Centers for Disease Control and Prevention (CDC)


Authorized for individuals ages 18 and up.
Type: mRNA
Dose: 2 doses 28 days apart
Efficacy: Based on evidence from clinical trials, the Moderna vaccine was 94.1% effective at preventing laboratory-confirmed COVID-19 illness in people who received two doses who had no evidence of being previously infected.
Source: Centers for Disease Control and Prevention (CDC)

Johnson & Johnson (Janssen)

Authorized for individuals ages 18 and up.
Type: Viral vector
Dose: 1 dose
Efficacy: The Johnson & Johnson (Janssen) vaccine was 66.3% effective in clinical trials at preventing laboratory-confirmed COVID-19 illness in people who had no evidence of prior infection two weeks after receiving the vaccine. People had the most protection two weeks after getting vaccinated.
Source: Centers for Disease Control and Prevention (CDC)



Vaccine development

Developing new vaccines is a thorough and careful process. Safety is the top priority during all phases of vaccine development, approval, and use.

Nurse vaccinating an older adult

FDA clinical trials

Before the U.S. Food and Drug Administration (FDA) can approve a vaccine, it has to be tested through clinical trials to make sure it is safe and see how well it prevents illness. COVID-19 vaccines were tested in large clinical trials, made up of far more participants than is usually required, to make sure they met well-established safety standards. Vaccines are also continually assessed and evaluated for safety with new populations, such as children. The participants of the trials include people of different ages, races, and ethnicities, as well as those with different medical conditions to make sure each vaccine is effective, across the board. Learn more about how medical experts ensure vaccines work both in clinical trials and the real world by visiting the CDC’s website.


An adult working in a test lab

Emergency use authorization (EUA)

During a public health emergency, such as the COVID-19 pandemic, the FDA can authorize safe and effective medical devices, treatments and vaccines more quickly using emergency use authorization (EUA). EUAs use the best available science to help necessary medical products get authorized more quickly. The COVID-19 vaccines went through all of the same steps in clinical trial phases that all vaccines go through. Learn more about EUAs by visiting the FDA's website.


Close up of a nurse with glasses wearing a mask

Continuous safety monitoring

There are systems in place that track common side effects and rare adverse, sometimes serious, reactions in people who receive any vaccine, including COVID-19 vaccines. The CDC and FDA monitor these systems in real time to make sure safety issues are detected as quickly as possible.

  • The Vaccine Adverse Event Reporting System (VAERS) is the national system that collects reports from health care professionals, vaccine manufacturers, and the public on adverse events that happen after vaccination. Reports of adverse events that are unexpected, appear to happen more often than expected, or have unusual patterns are followed up with specific studies. Providers are required to report any adverse events to this system.
  • V-safe is a new smartphone-based tool that makes it easy for people to report any health problems or serious reactions after they get their COVID-19 vaccines. Learn how to register and use v-safe by visiting the CDC’s website.
  • Vaccine Safety Data Link is a network of nine integrated health care organizations across the U.S. that conduct active surveillance and research. The system is also used to help determine whether possible side effects identified through VAERS are actually related to vaccination.

Frequently asked questions

See answers to frequently asked questions about COVID-19 vaccines, safety, and efficacy by opening the tabs below.

Are vaccines safe for pregnant and breastfeeding people?

COVID-19 vaccination is recommended for all people 12 years and older, including people who are pregnant, breastfeeding, or trying to get pregnant now or might become pregnant in the future.

Based on current data from the v-safe COVID-19 Vaccine Pregnancy Registry, scientists did not find an increased risk for miscarriage among people who received an mRNA COVID-19 vaccine before 20 weeks of pregnancy. This adds to the growing evidence of the safety of these vaccines. Additionally, previous findings from three safety monitoring systems did not find any safety concerns for pregnant people who were vaccinated late in pregnancy or for their babies.

The American College of Obstetricians and Gynecologists and 21 of the leading organizations representing experts in maternal care and public health professionals also issued a statement urging pregnant individuals to be vaccinated.

The increased risk of severe illness and pregnancy complications related to COVID-19 infection makes vaccination for pregnant people more urgent than ever. CDC and DHS recommend that pregnant people should be vaccinated now against COVID-19 if they have not yet received a COVID-19 vaccine. Learn more on the CDC website.

How were COVID-19 vaccines developed so quickly?

No safety steps were skipped during the development of COVID-19 vaccines. A number of factors allowed safe and effective COVID-19 vaccines to be available quickly.

  • Earlier research on other coronaviruses (SARS and MERS) jump started the COVID-19 vaccine development process. SARS was first detected in 2002, while MERS was first detected in 2012, and both have been researched ever since.
  • Through ground-breaking partnerships between leading medical experts, scientists were able to build on lessons learned from past pandemics (Zika, Ebola, H1N1) to make the COVID-19 vaccines.
  • Medical experts and other key players all dedicated their time, effort, and resources to developing COVID-19 vaccines.
  • Issuing an EUA shortened the official process, but did not skip any safety steps. For example, the FDA invited more experts to review than usual. With all hands on deck, the review process was shortened from months to weeks. The EUA allowed faster public access to vaccines.

Is the COVID-19 vaccine a live vaccine?

No. The Pfizer and Moderna COVID-19 vaccines are made with mRNA technology. The Johnson & Johnson vaccine is a viral vector vaccine, which means that it contains just a part of the virus that causes COVID-19 inserted into the backbone of an adenovirus vector. This vector poses no threat of causing illness in humans.

What ingredients are in the COVID-19 vaccines?

See full lists of ingredients for the PfizerModerna, and Johnson & Johnson vaccines.

The vaccines do not contain fetal cells, blood products, the live SARS-CoV-2 virus, mercury, egg, latex, pork products, preservatives, or microchips.

See DHS fact sheets for the full picture of what's in the Pfizer, Moderna, and Johnson & Johnson vaccines.

Are COVID-19 vaccines safe for people with underlying medical conditions?

Yes. People with underlying conditions can get the COVID-19 vaccine as long as they are not allergic to any of the ingredients in the vaccines. When checking, it is important to look at the detailed list (see answer to question above). Vaccination is important for people with underlying medical conditions because they may be at an increased risk of severe illness from COVID-19.

Learn more about vaccine considerations for people with underlying medical conditions to make an informed decision.

Is there risk of a severe allergic reaction with the COVID-19 vaccine?

Adverse reactions are possible, although they are very rare. Systems, like VAERS and v-safe, are in place to monitor for reactions to COVID-19 vaccines. This is why you may be asked to wait 15 minutes after receiving the COVID-19 vaccine so any reactions can immediately be addressed.

I am considering getting the Johnson & Johnson vaccine. What do I need to know?

Know that the Johnson & Johnson vaccine is safe and effective, and that the pause on administering the vaccine was lifted after an extensive safety review by independent experts, the CDC and the FDA. There is a risk, primarily for women ages 18-49, of a very rare but severe type of blood clotting. The vaccine fact sheet for providers and recipients and caregivers has been updated. Learn more about the pause lifted on the Johnson & Johnson vaccine.

Getting vaccinated is the most effective way to protect yourself and your family from the risks of COVID-19. The Johnson & Johnson vaccine is a one dose shot, meaning, you have full immunity 14 days after you receive it. You can look for vaccine by brand at

If you do receive the Johnson & Johnson vaccine, contact your health care provider immediately if you experience any of the following symptoms within three weeks of receiving your vaccine:

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

Will COVID-19 vaccines protect against any new strains of COVID-19?

Based on initial evidence all three authorized vaccines effectively reduce the risk of COVID-19 for all of the emerging variants.

Additional COVID-19 vaccine resources

Access resources and data about the COVID-19 vaccines, including their development and approval, safety, efficacy and more.

Vaccine data

Access the latest COVID-19 statistics and data, including vaccination distribution rates and how the information is tracked and reported.


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