By David Verhoeven, Iowa State University
While effective vaccines for COVID-19 should have heralded the benefits of mRNA vaccines, fear and misinformation about their supposed dangers circulated at the same time. These misconceptions about mRNA vaccines have recently spilled over into worries about whether their use in agricultural animals could expose people to components of the vaccine within animal products such as meat or milk.
In fact, a number of states are drafting or considering legislation outlawing the use of mRNA vaccines in food animals or, at minimum, requiring their labelling on animal products in grocery stores. Idaho introduced a bill that would make it a misdemeanour to administer any type of mRNA vaccine to any person or mammal, including COVID-19 vaccines. A Missouri bill would have required the labelling of animal products derived from animals administered mRNA vaccines but failed to get out of committee. Arizona and Tennessee have also proposed labelling bills. Several other state legislatures are discussing similar measures.
I am a researcher who has been making vaccines for a number of years, and I started studying mRNA vaccines before the pandemic started. My research on using mRNA vaccines for cattle respiratory viruses has been referenced by social media users and anti-vaccine activists who say that using these vaccines in animals will endanger the health of people who eat them.
But these vaccines have been shown to reduce disease on farms, and it’s all but impossible for them to end up in your food.
TRADITIONAL ANIMAL VACCINE APPROACHES
In food animals, several types of vaccines have long been available for farmers to protect their animals from common diseases. These include inactivated vaccines that contain a killed version of a pathogen, live attenuated vaccines that contain a weakened version of a pathogen and sub unit vaccines that contain one part of a pathogen. All can elicit good levels of protection from disease symptoms and infection. Producing these vaccines is often inexpensive.
Another major drawback for all three of these vaccine types is the time it takes to test and obtain federal approval to use them. Typically, animal vaccines take three or more years from development to licensure by the U.S. Department of Agriculture. Should new viruses make it to farms, playing catch-up using traditional vaccines could take too long to contain an outbreak.
ADVANTAGES OF ANIMAL MRNA VACCINES
All cells use mRNA, which contains the instructions to make the proteins needed to carry out specific functions. The mRNA used in vaccines encode instructions to make a protein from a pathogen of interest that immune cells learn to recognise and attack. This process builds immunological memory, so that when a pathogen carrying that same protein enters the body, the immune system will be ready to mount a quick and strong response against it.
Compared to traditional vaccines, mRNA vaccines have several advantages that make them ideal for protecting people and farm animals from both emerging and persistent diseases.
Unlike killed or subunit vaccines, mRNA vaccines increase the buildup of vaccine proteins in cells over time and train the immune system using conditions that look more like a viral infection. Like live attenuated vaccines, this process fosters the development of strong immune responses that may build better protection. In contrast to live attenuated viruses, mRNA vaccines cannot revert to a pathogenic form or mix with circulating pathogens. Furthermore, once the genetic sequence of a pathogen of interest is known, mRNA vaccines can be produced rather quickly.
