March 27, 2026

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Why you should keep getting mRNA vaccines

The COVID pandemic ushered mRNA vaccines into the spotlight, and the technology has even greater potential. Here’s what to know about the way that they work, their safety, and more

By Meghan Bartels edited by Lauren J. Young

quantic69/Getty Images

Messenger RNA, or mRNA, vaccine technology burst onto the scene early in the COVID pandemic, leaving many people playing catch-up on the science behind the advance. Within the first six months of their availability, COVID vaccines prevented some eight million COVID infections, one study has shown.

But despite the vaccines’ success, critics have fought against the COVID shots’ rollout and mRNA vaccine technology more broadly. Recently, the Trump administration’s Food and Drug Administration initially declined to review an mRNA vaccine for influenza. The FDA has since reversed its decision, but the Trump administration has made other moves to target the technology, including cutting nearly $500 million in grant funding for mRNA vaccine projects. Despite setbacks, many scientists believe mRNA vaccines will not only help control infectious disease but also improve cancer treatment.

How do mRNA vaccines work?

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All vaccines are designed to train the immune system to recognize a specific pathogen or other threat to the body. Vaccines that protect against infectious diseases have traditionally introduced a weakened or inactivated virus or bacterium or a distinctive protein from its surface to trigger an immune response that is milder than an infection. If the body encounters the same signal again, it is better prepared to fight off the invader.

In an mRNA vaccine, the vaccine gives the body a section of mRNA, genetic material copied from DNA that encodes one of the pathogen’s proteins. This piece of mRNA acts as a template for the body to produce and then recognize that protein.

Some vaccine skeptics have raised concerns about this use of foreign genetic material. Contrary to some claims, “it’s not going to change your DNA,” says Sabrina Assoumou, an infectious disease physician at Boston Medical Center and an associate professor at Boston University. Extensive research has shown that the snippet of mRNA enters cells but not the cell nucleus, where most of your genetic material is stored.

And mRNA is easily broken down by the body. Humans ingest mRNA all the time from the food we eat, but our digestive system deactivates it. “Cells have safeguards so that we don’t get invaded by nucleic acids that just happen to be about,” says Jennifer Pancorbo, an expert in pharmaceutical biomanufacturing at North Carolina State University. To prevent the genetic material from disassembling too quickly, vaccine developers enclose the mRNA in a specialized mix of tiny fatty molecules called lipid nanoparticles. These molecules form a protective bubble around the mRNA that makes it easy for cells to absorb this genetic material. There the mRNA remains for hours or, at most, a few days before a specialized enzyme breaks it down.

Additionally, mRNA vaccines include salts, sugars, acids and acid stabilizers, which make them more shelf-stable and enable them to be frozen.

How do mRNA vaccines compare with other types of vaccines?

The oldest approach to vaccination in use today includes either inactivated pathogens—such as those in most modern polio vaccines—or pathogens that remain viable but have been weakened enough not to trigger disease—such as those in the measles, mumps and rubella, or MMR, vaccine. These “whole-virus” vaccines are simple to make, and researchers understand in detail how they operate in the body. And they provide strong protection from an infection. The inactivated and weakened pathogens look “a lot like the bad guy,” Pancorbo says, “so it’s very easy for the immune response to be very specific and mount really quickly against that pathogen if you happen to be exposed to it.” That said, whole-virus vaccines can cause more unpleasant side effects, and in rare cases, weakened live pathogens can redevelop infectious capability.

Perhaps the most common vaccine approach is called a subunit vaccine, which contains only specific parts of a pathogen—often proteins. Subunit vaccines are safer than whole-virus ones because there’s absolutely no chance of a virus regaining the ability to infect people. But these vaccines sometimes require additional compounds called adjuvants or other strategies that have been shown to safely boost the immune system’s res