Despite the proven efficacy of mRNA vaccines for COVID-19, misconceptions and misinformation surrounding their safety have led to concerns about their use in agricultural animals and the potential presence of vaccine components in animal products like meat or milk. Several states are considering legislation to outlaw or label mRNA vaccines used in food animals. mRNA vaccines have demonstrated disease reduction on farms and are highly unlikely to end up in the food supply.
Traditional vaccines for animals, such as inactivated, live attenuated, and subunit vaccines, have limitations in terms of immune response strength, vaccine effectiveness against evolving pathogens, and the time required for development and approval. In contrast, mRNA vaccines offer advantages for protecting both humans and animals from emerging and persistent diseases. They stimulate strong immune responses and can be produced relatively quickly. They do not revert to pathogenic forms or mix with circulating pathogens. Moreover, mRNA vaccines come in different forms, some of which are self-amplifying and potentially require less mRNA for immunity.
Regarding the persistence of mRNA vaccine components, the technology used in mRNA vaccine production has been refined to allow the mRNA to evade immediate rejection by the body’s antiviral defenses. COVID-19 mRNA vaccines incorporate modified nucleotides to enhance stability within cells. However, mRNA vaccines do not last long enough in animals to result in any vaccine component being present in animal products. Stringent withdrawal periods are established for animal vaccines, ensuring that no vaccine component is present at the time of milking or slaughter. Residual mRNA molecules, even if consumed, are rapidly degraded by the gastrointestinal tract.
While mRNA vaccines for animals are still in development, they undergo safety and efficacy testing in clinical trials, similar to human vaccines. Regulatory approval for animal use requires a level of protection against infection or disease symptoms, and vaccines must be fully cleared from the animal’s body before they can be used for human consumption.
The future adoption of mRNA vaccines for livestock remains uncertain and depends on factors such as manufacturing cost, cold storage requirements, and efficacy compared to other vaccine types. Limiting the use of mRNA vaccines in animals would hinder a promising method to protect animals from pathogens that existing vaccines cannot effectively combat.