Are mRNA vaccines ‘true’ vaccines?

Are mRNA vaccines new? 

It’s true that there were no FDA-authorized mRNA vaccines in the U.S. before the COVID-19 vaccines. But the technology is not new. Over the past few decades, scientists have run clinical trials with mRNA vaccines for influenza, Zika, Ebola, cytomegalovirus, and rabies.

How are mRNA vaccines different from other vaccines? 

Vaccines are proteins, sugars, or nucleic acids (DNA and RNA) that are designed to teach your immune system to make antibodies. These antibodies can fight the disease. When you get a vaccine, your body learns to battle the bug before you are exposed. But different types of vaccines work in different ways. 

What are the types of vaccines?

Image from the World Health Organization

There are three general types of vaccines. Let’s break them down.

1. Whole virus vaccines use disease-causing pathogens. 

  • Live-attenuated vaccines simulate natural infection with a weaker version of the virus. Example: measles, mumps, and rubella (MMR) and chickenpox vaccines.
  • Inactivated vaccines ‘kill’ the virus’s genetic material with heat, radiation, or chemicals. Example: polio and rabies vaccines.
  • Viral vector vaccines use a different virus that has been stripped of its disease-causing ability. That virus inserts a code in the body’s cells that will protect against the targeted virus. Example: Johnson & Johnson and Oxford/AstraZeneca COVID-19 vaccines.

2. Subunit vaccines contain very specific, isolated protein parts of the virus. Example: diphtheria, tetanus, and pertussis (DTaP) vaccine for children.

3. Nucleic acid vaccines are the newest type and don’t include any part of the virus. Instead, they provide a DNA or RNA blueprint that tells the cell to make the viral protein. This protein teaches the immune system what to look for during an infection. Example: Pfizer-BioNTech and Moderna COVID-19 mRNA vaccines. 

Check out global progress of COVID-19 vaccines by type here

Are mRNA vaccines safe in the long-term?

The design of mRNA vaccines and the results of clinical studies suggest that they are safe. But the best evidence is that the Pfizer-BioNTech and Moderna mRNA vaccines are the most widely distributed of their kind. Worldwide, over 60 million people are fully vaccinated -- at least 50% of likely received an mRNA vaccine. 

The chances that you could die or suffer long-term consequences from getting sick with COVID-19 are far higher than the chance that you’ll experience any adverse events from an mRNA COVID-19 vaccine. 

Last update: 5 March, 2021, 16:45 ET

Science review: BK, ERS