Veterinary vaccines are being used significantly more often to safeguard both the health of animals and the general public.
The livestock and poultry sectors have had significant success with first-generation veterinary vaccinations, such as inactivated and live-attenuated vaccines.
Animals on farms (livestock), in the wild, and as pets are all protected against deadly diseases by veterinary vaccines. The vaccines also lessen the demand for antibiotics and make it possible to raise enough livestock to feed the world’s expanding population. One of the greatest successes in veterinary medicine was the Global Rinderpest Eradication Program, which involved veterinary immunisation. In 2011, it contributed to the complete eradication of rinderpest. The first animal sickness to be eradicated worldwide was this one.
There is proof that unintended human exposure to veterinary vaccines can result in negative side effects. These traditional immunizations do, however, have certain possible drawbacks. Live-attenuated vaccines are linked to the danger of disease transmission, but inactivated vaccines do not result in broad-spectrum immune responses.
The second-generation (recombinant subunit vaccines) and third-generation vaccinations have addressed the drawbacks of the first-generation vaccines (DNA, RNA, viral-vector-based, and chimeric vaccines).
Marker vaccinations that eliminate mutations of wild-type pathogens are another innovative idea.
Vaccines for animals are just as important for human health. The vaccinations given to cattle and poultry aid in preserving the best possible levels of animal health and enhance food animal output. Together, these initiatives enhance the amount of high-quality animal protein available to the general public.
The world’s population is expected to reach 8 billion people in 2022, according to UN projections.
In 2050, this is anticipated to increase to 9.7 billion. A large increase in animal food production is required to satisfy the rapidly expanding human population’s appetite. Vaccines for animals are crucial in addressing this requirement. Vaccinations for animals also lower the danger of zoonotic infections, which can spread from animals to people via a variety of routes. By giving rabies vaccines to domestic and wild animals, human rabies in developed nations has all but been eradicated.
The most notable instance of rising zoonotic disease risk for humans is the ongoing coronavirus disease 2019 (COVID-19) pandemic.
The main factors that cause pathogens from animal to human populations to spread, resulting in the introduction of new and fatal zoonotic illnesses, are altered anthropogenic land use, environmental degradation, globalised trade, and travel. Novel veterinary vaccines being developed quickly may be key to preventing the spread of these illnesses. Veterinary vaccinations created against different pathogens (such as Escherichia coli and Salmonella enteritidis) assist lower the risk of humans contracting foodborne illnesses by reducing pathogen shedding from diseased animals.
Antibiotics that are used to treat illnesses in animals are less frequently required thanks to veterinary vaccinations. Antibiotic overuse can cause the growth of resistant bacteria in animals. Humans may contract resistant germs from animals if they consume raw or undercooked animal products. Humans can contract resistant germs by consuming vegetables, fruits, or water that has been tainted with animal waste. Antibiotic resistance is decreased when vaccinations rather than drugs are used to prevent infections.
How could immunizations for animals harm human health?
Increased exposure to vaccine strains in humans could result from increased use of veterinary vaccines, which could have a negative impact on human health. Animals receive a lot of veterinary immunizations either orally or nasally (aerosol vaccines). These vaccination delivery methods increase the likelihood that adjacent individuals will unintentionally come into contact with vaccine strains.
There are currently many live-attenuated vaccinations available for animal usage. Live vaccination injection to food animals can raise the chance that people will become exposed to vaccine strains, which could then be harmful to their health.
Elderly people, cancer patients, organ transplant recipients, those infected with HIV, and other patients with impaired immune systems are particularly susceptible to experiencing negative health effects after being exposed to animal vaccination strains.
In terms of occupational exposure, veterinarians are more likely to experience needlestick injuries, open wounds, or eye splashes that expose them to live vaccination strains. People who work in fish and animal farms may also be exposed to veterinary vaccines on the job. Research looked at workplace exposure to veterinary biologics have found that unintended autoinoculation of live anthrax vaccine, Brucella vaccine, and vaccines against Newcastle virus can cause both local and systemic infections in people.
An allergic or inflammatory reaction at the injection site is one of the most typical signs of veterinary vaccination exposure (inoculation). These adverse reactions are brought on by adjuvants used in vaccination formulations. Evidence suggests that accidental injection in the fingers or joints may result in necrosis of the fingers or sterile joint abscesses. It has been discovered that auto-injection can occasionally result in anaphylactic reactions that demand hospitalisation.
People can purposefully expose themselves to veterinary vaccines in addition to incidental exposure.
For instance, individuals occasionally utilise livestock vaccines as prophylaxis against specific illnesses (such as West Nile encephalitis, Lyme disease, and anthrax) for which there is not yet a human vaccine.
Parvathy Sukumaran 
