How do mRNA vaccines work?

An mRNA vaccine uses messenger ribonucleic acid to teach our cells to make a harmless small protein that mimics the “spike protein” on the outer membrane of SARS-CoV-2, the virus that causes the COVID-19 disease (the spike protein is what allows the virus to bind to our cells and cause infection).

Once our cells make these small spike protein dupes (mimicking the spike protein found on the outside of SARS-CoV-2), our immune system recognizes that they do not belong. We then experience an immune response, where our body begins making antibodies, similar to natural infection but without the risks of developing COVID-19. If you are exposed to the SARS-CoV-2 virus, you will be protected. Even if you have a weak immune response to the vaccines, you will still be protected from severe illness.

It is important that everyone who can get vaccinated do so. The more SARS-CoV-2 spreads, the more opportunities it has to form variants, mutations of the original virus. Currently, the mRNA vaccines are very effective against variants, but if there are enough mutations impacting the spike proteins on the outside of the virus it is possible our immune system will no longer recognize the virus as it was trained.

Boosters may be required, depending on how long the immunity given by the vaccine lasts, and depending on how many variants form. Currently, no booster shots are recommended, but researchers are in development, and the US Surgeon General stated that Americans should expect to have another shot within a year. While a typical booster shot is the same vaccine as previously given (e.g., a tetanus booster shot is the same vaccine dose given every 10 years), COVID-19 vaccines are likely to be unique each year, similar to the flu shot.

Some things to remember:

  • The vaccines cannot give someone COVID-19—they do not contain any virus.
  • They cannot interact or change our DNA. The mRNA never enters the nucleus of the cell (where DNA is stored), and the mRNA is broken down and removed after the cell codes for the dupe spike proteins. This means that once the cell has made the necessary proteins for an immune response, the mRNA from the vaccine is discarded.
  • COVID-19 mRNA vaccines are rigorously tested for safety; emergency use authorization does not mean they are not held to the same standards as all other vaccines in the United States.
  • mRNA vaccines are new for public use, but not to researchers. Researchers have been studying them for decades, as they can be developed quickly, are highly effective, and are relatively inexpensive to produce. They have huge promise for viruses such as HIV or even cancer vaccines.

Encourage your employees to get vaccinated. For further reading about COVID-19 go to the Washington State Labor and Industries page: For business resources related to sick leave and the COVID-19 vaccine, go to

For industry-specific COVID-19 guidance from L&I, go to