Each vaccine has its own risks and benefits, but those that have been approved for use are effective at reducing risk of a COVID-19 infection. The best vaccine for an individual is one they can access and feel comfortable taking.

All data and statistics are based on publicly available data at the time of publication. Some information may be out of date. Visit our coronavirus hub for the most recent information on the COVID-19 pandemic.

The Food and Drug Administration (FDA) has approved or authorized three vaccines: Moderna, Pfizer-BioNTech, and Johnson & Johnson’s Janssen. The Centers for Disease Control and Prevention (CDC) recommend getting Moderna or Pfizer-BioNTech if they are available.

However, different vaccines are available globally. Many countries are starting to approve the new Novavax vaccine and the Oxford AstraZeneca vaccine that is common in Europe.

Like all medical treatments and medications, vaccines come with risks and benefits.

The data on COVID-19 vaccines show that side effects are minimal. While there have been rare instances of serious side effects, the risk of adverse events from a COVID-19 infection is much higher.

Read more to learn about the approval status, dosage, efficacy, and side effects of each COVID-19 vaccine.

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The Pfizer-BioNTech vaccine, also called COMIRNATY, is an mRNA vaccine.

Overview

It uses a lipid, or a fatty acid, to deliver a piece of the virus’s genetic code. However, it does not contain the virus — rather, it contains a piece of messenger RNA (mRNA) that codes for the virus’s unique spike protein.

The body responds to this spike protein as an intruder and develops the immune reaction it needs to fight it. The vaccine teaches the body how to fight the COVID-19 virus when it encounters the real thing.

The vaccine’s contents leave the body and do not alter a person’s genetic code.

It does not contain:

  • gelatin
  • fetal cells
  • latex
  • eggs or other common allergens
  • latex
  • preservatives
  • metals
  • antibiotics

Approval status

The FDA has approved the vaccine for individuals over the age of 16. It has an emergency use authorization for people over the age of 5 and for booster shots.

Dosage

The initial series is two injections, at least 21 days apart, and a booster requires a third shot.

The dosage is:

  • Ages 5-11: two 0.2 milliliter (mL) doses
  • Ages 12-15: two 0.3 mL doses
  • Ages 16 and older: two 0.3 mL doses

It is safe to mix and match this vaccine with others.

Side effects

The vaccine’s side effects are typically mild, and some people report having more side effects after the second vaccine.

They commonly report cold and flu-like symptoms such as:

  • fever
  • headache
  • muscle aches
  • soreness at the injection site
  • nausea
  • chills
  • fatigue

The side effects usually disappear within a few days. They happen because of the immune system’s reaction to the injection, so having side effects shows that the vaccine is working.

Efficacy

According to the CDC, the full series of the vaccine is more than 95% effective at preventing laboratory-confirmed COVID-19 infections in adults who are not immunocompromised and have no documented history of a COVID-19 infection.

In children ages 5–15 and people with immunocompromising conditions, the vaccine was at least 90% effective.

Among adults without immunocompromising conditions between March 11 and August 15, 2021, the vaccine offered 88% efficacy against hospitalization. This time period extends into the Delta wave of the pandemic.

Preliminary data from Pfizer showed that three doses of the vaccine could neutralize the Omicron variant.

Other research is still ongoing. A 2022 study found that in a lab setting, a booster could offer some immunity to Omicron.

The Moderna vaccine, also called Spikevax, is an mRNA vaccine

Overview

Although it works similarly to the Pfizer vaccine, it delivers a slightly higher dose.

Like Pfizer, it contains mRNA that gives instructions for fighting the spike protein on the COVID-19 virus. This produces an immune reaction that trains the body to fight the virus if it encounters it in the real world.

The vaccine’s contents leave the body and do not alter a person’s genetic code. It does not contain any of the following:

  • viruses
  • bacteria
  • fetal cells
  • eggs
  • preservatives
  • metals
  • antibiotics
  • latex

Approval status

The FDA has approved the Moderna vaccine for adults ages 18 and over. It also has an emergency use authorization as a one-dose booster 5 months after receiving another vaccine.

Moderna is not approved for use in children.

Dosage

The initial Moderna series requires two injections, with a third shot as a booster.

It has earned an emergency use authorization for people over the age of 18. Each dose is 0.5 mL, and the two shots should be at least 28 days apart.

Like the Pfizer vaccine, it is safe to mix and match this vaccine with others.

Side effects

Because they are both mRNA vaccines, the side effects of Moderna are similar to those of Pfizer.

Some people report mild cold or flu-like symptoms shortly after getting vaccinated with side effects more frequently appearing after the second vaccine than the first. Some common side effects include:

  • headache
  • fatigue
  • chills
  • fever
  • body aches
  • gastrointestinal issues
  • redness, swelling, and pain at the injection site

Efficacy

Among adults without immunocompromising conditions between March 11 and August 15, 2021, Moderna was 93% effective against hospitalization due to COVID-19. This time frame includes the Delta wave, but not Omicron.

A 2022 study found that an additional Moderna booster dose could provide some immunity against the Omicron variant while the two-dose series did not. Moderna is working on a booster specific to new variants.

The J&J/Janssen vaccine is a single-shot viral vector vaccine.

On May 5, 2022, the FDA limited the Emergency Use Authorization (EUA) granted to the vaccine. The Johnson & Johnson vaccine is now only authorized for use in people ages 18 years and older who can’t receive other approved COVID-19 vaccines or who would choose not to be vaccinated otherwise. Individuals who cannot receive other COVID-19 vaccines include those for whom it is not clinically appropriate or who don’t have access to the Moderna or Pfizer vaccine.

Overview

Unlike Pfizer and Moderna, it is not an mRNA vaccine. Instead, it works similarly to traditional vaccines.

The vaccine uses a weakened form of a harmless adenovirus that delivers genetic code for the unique COVID-19 spike protein. This creates an immune reaction that prepares the body to fight COVID-19. The vaccine’s contents leave the body and do not alter a person’s genetic code.

It cannot infect a person with COVID-19 or the adenovirus, and it does not contain:

  • preservatives
  • antibiotics
  • metal
  • latex
  • fetal parts
  • eggs

The injection is generally less effective than the Moderna and Pfizer vaccines.

The CDC urges people to choose the mRNA vaccines unless they are inaccessible. While J&J/Janssen is safer than going unvaccinated, it may have worse side effects than other vaccines.

Approval status

The FDA has approved the vaccine on an emergency use authorization basis for people over the age of 18. It has also given emergency use authorization for a booster at least 2 months after the first dose.

The vaccine is not approved for children or anyone under the age of 18.

Side effects

The most common side effects of this vaccine include mild cold or flu-like symptoms such as nausea, fever, chills, and muscle aches.

Very rarely, however, a person may develop a blood clot.

The CDC estimates that roughly 3.83 people per million will have this side effect. However, the blood clot rate is much higher with a COVID-19 infection, with as many as 1 in 5 people experiencing a blood clot. Of 18.2 million J&J/Janssen vaccine recipients, just 57, or 1 in more than 300,000, have reported blood clots.

Dosage

The J&J/Janssen vaccine is a single-dose vaccine. It has an emergency use authorization in the United States for people over the age of 18.

A person can also get a single dose booster, but the CDC recommends choosing Pfizer or Moderna instead. It is safe to mix and match this vaccine with others.

Efficacy

Between March 11 and August 15, 2021, a time period that included the Delta wave but not Omicron, the J&J/Janssen vaccine was 71% effective in preventing COVID-19 hospitalization.

The Oxford AstraZeneca vaccine works very similarly to the J&J/Janssen vaccine.

Overview

It uses an adenovirus to deliver the COVID-19 spike protein into the body. This creates an immune reaction that trains the body to fight the virus if it encounters it again.

Approval status

The AstraZeneca vaccine does not have FDA approval in the United States. However, it is popular in Europe because it is less expensive to produce than mRNA vaccines and is easier to store.

Dosage

The World Health Organization (WHO) recommends two doses of 0.5 mL each, and the vaccines should be 8 to 12 weeks apart. It is safe to mix and match this vaccine with others.

Side effects

Some common side effects include:

  • fever
  • chills
  • muscle aches
  • flu and cold-like symptoms
  • pain at the injection site

In rare cases, the AstraZeneca vaccine may cause blood clots. The risk of blood clots from COVID-19 is exponentially higher.

Efficacy

The AstraZeneca vaccine prevents symptomatic infection in 6 out of 10 people. Early trials, prior to Delta and Omicron, showed an 80% efficacy at preventing hospitalization.

The Novavax vaccine uses older vaccine technology — specifically, a protein subunit.

Overview

This vaccine delivers an antigen synthesized from the COVID-19 spike protein to train the body to fight the virus. It does not contain a live virus, and the spike antigen cannot replicate.

Approval status

Novavax is not yet approved for use in the U.S., but a request for an emergency use authorization has been submitted. As of November 2021, it is approved for use in Indonesia and the Philippines.

Dosage

The WHO recommends two 0.5 mL doses given 3–4 weeks apart.

It is safe to mix and match this vaccine with others.

Side effects

Side effects include:

  • fatigue
  • headache
  • fever
  • muscle pain
  • injection site swelling, pain, and redness

Efficacy

In clinical trials, the efficacy of Novavax against mild, moderate, and severe disease was 90%. Researchers do not know if it prevents infection or transmission and are conducting additional research.

There are four types of COVID vaccines in use or in clinical trials:

TypeHow they workAvailable vaccines
mRNAThese use messenger RNA to give the body’s cells information about how to fight the virus, usually by providing information about the virus’s spike protein. Pfizer-BioNTech, Moderna
Whole virusThese use whole viruses to provoke an immune response.Coronavac, Covilo, Covaxin
Protein subunitThese use a component of the virus, usually a protein, to train the body how to fight a virus by inducing an immune response. Novavax
Viral vectorThese vaccines use a harmless virus to train the body how to fight a harmful virus.J&J/Janssen, Oxford-AstraZeneca

Current CDC guidelines suggest that vaccines are safe for most people — including those who are pregnant, breastfeeding, and have immunocompromising conditions. A person should only avoid a vaccine if they have had an allergic reaction to a specific ingredient in that vaccine.

The availability of vaccines varies from location to location. In areas that offer multiple vaccines, a person can often choose their vaccine. This might require going to a specific provider or scheduling the vaccine for a specific day.

It is usually safer to get the first available vaccine to maximize a person’s protection against COVID-19.

All currently approved COVID-19 vaccines are safe for use and reduce a person’s chance of severe illness with the virus.

Although all vaccines come with side effects, the risk of side effects from COVID-19 remains much higher. Except for a severe allergic reaction or a known allergy, there is no reason to avoid a COVID-19 vaccine.