Vaccine skepticism has spread to our pets.

More than half of U.S. dog owners expressed concerns about vaccinating their dogs, including against rabies, according to a new study published Saturday in the journal Vaccine. The study comes as anti-vaccine sentiments among humans have exploded in the wake of the COVID-19 pandemic.

“Canine vaccine hesitancy is pervasive,” said Matt Motta, one of the paper’s authors and a political scientist at Boston University’s School of Public Health who studies hesitancy. “Honestly, we were pretty surprised.”

This is not the first indication that insurgent anti-vaccine attitudes have impacted our furry friends. A study published in the Canadian Veterinary Journal in 2021 found overlap between the movement against mandatory childhood vaccines and vaccine-resistant pet owners. Another found a link between people skeptical of vaccinating their dogs and those who believe vaccines cause autism in children – a false rumor that’s been long-debunked.

Pets are now often considered to be a member of the family, and their health-care decisions are weighed with the same gravity. But the consequences of not vaccinating animals can be just as dire as humans. Dogs, for example, are responsible for 99% of rabies cases globally. Rabies, which is often transmitted via a bite, is almost always fatal for animals and people once clinical signs appear. A drop in rabies vaccination could constitute a serious public health threat.

In the new study, the authors surveyed 2,200 people and found 53% had some concern about the safety, efficacy or necessity of canine vaccines. Nearly 40% were concerned that vaccines could cause dogs to develop autism, a theory without any scientific merit.

“What this demonstrates is that COVID fundamentally changed how Americans look at vaccines,” said Motta, who co-authored the paper alongside his sister, Gabrielle Motta, a veterinarian in Pennsylvania, and political scientist Dominik Stecula at Colorado State University.

Most states require rabies vaccinations for both cats and dogs. Other shots, like the parvovirus vaccine, are critical for dogs’ health. Vaccination rates for pets are not tracked the same way that rates for childhood shots in humans are tracked, but the U.S. is not considered a rabies reservoir. According to the U.S. Centers for Disease Control and Prevention, around 60 to 70 dogs and more than 250 cats are reported rabid each year.

The pandemic, along with a broader political movement targeting vaccines, brought skepticism to new levels. Less than 80% of Americans now believe childhood vaccines are important, compared to 93% before the pandemic, according to an April analysis from UNICEF that called waning childhood vaccinations a “red alert” situation.

Some states and activists have targeted childhood vaccine mandates required for kids to attend school, and national kindergarten vaccination rates for some diseases have dropped consistently over the past two years, according to the CDC. Declining vaccination levels even before the pandemic allowed the measles to make a comeback for the first time in years

“We are living in a world where states are considering rolling back vaccine requirements,” Motta said. “What’s to say pets aren’t the next frontier?”