Non-vaccination of dogs is linked to uncompleted COVID-19 vaccination protocols of owners.

Despite the known importance of vaccines as one of the greatest achievements in medical science, vaccine hesitancy has been increasing in the last decade and has become a major threat to global health. The growth of vaccine hesitancy worldwide became more evident with the onset of COVID-19 and raised the fear that this hesitancy would also impact companion animal vaccination. This study aimed to characterize vaccine-hesitant groups regarding companion animals and human vaccinations, as well as to explore the possible association between vaccine hesitancy in pets and their owners. An anonymous online survey containing 27 closed questions was conducted, including questions about dog health, such as vaccination, neutering, and homeopathy use, as well as questions about the COVID-19 vaccination status of the owner and motivations for vaccinating or not vaccinating their pets. Most participants (81.5 %) reported receiving three or more doses of the COVID-19 vaccine. Not vaccinating against COVID-19 or having an incomplete vaccination protocol was associated with an increase in the age range of participants (odds ratio [OR] = 1.43), not having higher education (OR = 7.70), and being in extreme income ranges (less than two minimum wages [OR = 7.57] and more than 10 [OR = 5.20]). The use of homeopathy in humans (OR = 3.24) and dogs (OR = 3.74) was associated with non-vaccination against COVID-19. Owners who were not fully vaccinated against COVID-19 were almost six times more likely to not vaccinate their dogs (OR = 5.94). Non-vaccination of dogs was also associated with non-neutering (OR = 3.56), keeping the dog in contact with other dogs (OR = 2.09), and an increase in the number of dogs in the house increased the chance of not vaccinating the animals (OR = 1.30). The present study revealed a strong association between non-vaccination against COVID-19 and non-vaccination in companion dogs, raising the hypothesis that vaccination hesitancy is a growing challenge in veterinary medicine. In addition, the characteristics of Brazilians who are reluctant to be vaccinated against COVID-19 or immunize their companion animals are described here for the first time.

Forty years of canine vaccination.

During the last 40 years vaccines have been developed that have greatly reduced the incidence of infectious diseases of dogs. In general, modified live products have been superior to inactivated vaccines for dogs. It can be expected that recombinant and/or DNA vaccines may dominate the market in the future. Although most vaccines on the market are safe and efficacious, there have been exceptions where disease was induced by vaccination or dogs were not protected. The failure of protection may in part be due to variations in individual vaccine batches. Only potency tests but not efficacy tests are required, which may not be sufficient. For example, a virus titer in a vaccine may be meaningless if the minimum protective dose is not known. Overattenuated virus (e.g., CDV-Ond or parvovirus in cat cells) may have a high titer in tissue culture but is not immunogenic. The question of frequency of vaccination of dogs should be addressed. Annual revaccinations for CDV, CPV, and CAV are probably not needed. However, it would be desirable to collect more data to support less frequent vaccinations. Annual immunization for bacterial diseases such as kennel cough, Lyme disease, and leptospirosis should continue. It also would be desirable to develop more oro/nasal vaccines, perhaps combined with newly developed vectors that are less likely to induce undesirable side effects that may be seen after parenteral vaccination. Finally a word of warning against homeopathic "nosodes" to replace tested canine vaccines. They will appear highly effective as long as the majority of dogs remain vaccinated. As soon as a nonvaccinated dog population is large enough to allow virulent agents to spread, disease outbreaks will occur and we will be back where we began 40 years ago.