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Vaccines teach our immune system how to fight viruses in a way that prevents serious complications. The COVID-19 vaccines are an example of this. The vaccines that are currently authorized and recommended to prevent COVID-19 are from:

  • Pfizer-BioNTech
  • Moderna
  • Johnson & Johnson / Janssen

There are a few other COVID-19 vaccines with clinical trials in progress that may receive Emergency Use Authorization at a later time. These include from:

  • Oxford-AstraZeneca
  • Novavax

mRNA Vaccines

The Pfizer-BioNTech and Moderna vaccines use mRNA (messenger RNA). mRNA vaccines are a new type of vaccine that works in a different way than other vaccines you may have received in the past, like the flu shot and chicken pox vaccines. However, the outcome is the same – it protects you from getting a specific illness.

mRNA vaccines give our body’s cells instructions to make a protein specific to the virus we’re trying to protect against. Then the body’s immune cells recognize that the protein does not belong and fight it off by creating antibodies. The COVID-19 mRNA vaccines specifically give our cells instructions for making a piece of “spike protein,” which is found on the surface of the virus that causes COVID-19 (SARS-COV-2).

When our immune cells recognize and attack this spike protein, our body learns how to protect itself against COVID in the future. Like other vaccines, mRNA vaccines give individuals protection without them ever having to risk the serious consequences of getting sick with COVID-19.

While the COVID-19 mRNA vaccines are the first of their kind, researchers have been studying and working with potential mRNA vaccines for more than a decade.

Both the Pfizer-BioNTech and Moderna COVID-19 vaccines are mRNA vaccines. However, there are a few differences between the two that individuals should keep in mind:

Pfizer-BioNTech COVID-19 Vaccine

The FDA-approved Pfizer-BioNTech mRNA vaccine is recommended for people 16 and over. The Pfizer vaccine continues to be available under emergency use authorization for children ages 12 to 15. The shot is given by injecting it into the muscle of the upper arm.

It’s given in two doses, 21 days apart, and does not contain eggs, preservatives or latex.

Based on evidence from clinical trials, the vaccine is 95% effective at preventing COVID-19 in those who had no evidence of being previously infected. This means that the vaccine was protecting them, rather than the antibodies people get after they are infected with the coronavirus.

Read about the side effects of this vaccine and individuals who should not receive it.

Moderna COVID-19 Vaccine

The Moderna mRNA vaccine is recommended for individuals over the age of 18 and is given by injection in the muscle of the upper arm.

It is given in two doses, 28 days apart, and does not contain eggs, preservatives or latex.

Based on evidence from clinical trials, the vaccine was 94.1% effective at preventing COVID-19 illness in individuals who had no evidence of being previously infected.

Read more about the side effects of this vaccine and individuals who should not receive it.

Johnson & Johnson / Janssen Vaccine

The Johnson & Johnson / Janssen vaccine is a viral vector vaccine. Viral vector vaccines are a type of vaccine used to protect against viruses. A few are currently being researched for protection against COVID-19.

This type of vaccine uses live (but safe) viruses to carry instructions to our cells. In the case of COVID-19, these instructions allow our body to create the “spike protein” that our immune cells will recognize as a part of the virus that causes COVID-19 (SARS-COV-2). This gives our immune system the ability to build protection for us if we’re ever exposed to SARS-COV-2. This type of vaccine and the mRNA vaccine are slightly different in how they get the instructions to our cells, but they are the same in how they help our bodies protect us against the coronavirus.

NOTE: As of April 25, 2021, the CDC and FDA have announced to resume the use of the Johnson & Johnson COVID vaccine. A review of the data showed that the potential benefits outweigh its known and potential risks. The CDC says that women younger than age 50 should be aware of the rare but increased risk of thrombocytopenia syndrome (TTS) following the Johnson & Johnson vaccine, and that there are other vaccine options available. Learn more from the CDC.

Page last updated August 30, 2021.