AIn early 2021, four orangutans and five bonobos were the first great apes in an American zoo to receive vaccinations against Covid-19. An outbreak in the San Diego Zoo’s western lowland gorilla troop had caused panic among staff after the virus spread among the animals, likely from an asymptomatic zookeeper. Eight gorillas tested positive – with symptoms such as runny noses, lethargy and coughing – and there were fears that the virus could spread to other primates.
“We were approached by the San Diego Zoo to ask if we had a vaccine because the primates got sick. Fortunately, we had a few that we thought would be appropriate, ”recalls Dr. Mahesh Kumar, a senior vice president at US veterinary pharmaceutical company Zoetis, which developed the shot.
The great apes in California have made a full recovery, but from the start of the pandemic there was fear for the well-being of our closest cousins. In March 2020, experts warned it could destroy populations of chimpanzees, gorillas and orangutans due to their genetic proximity to humans. National parks in the Democratic Republic of the Congo and Rwanda quickly closed their doors to tourists as a precaution, and many park rangers now follow strict guidelines for social distance around the animals. So far, the warnings have not materialized, but the virus has spread rapidly through other animal groups.
The Zoetis vaccine given to the great apes at the San Diego Zoo in January and February is being developed specifically for mink after outbreaks on dozens of farms around the world. Sars-CoV-2 is highly transferable between animals and has a high morbidity and mortality. According to the New York Times, another American company and researchers in Russia are also developing vaccines against mink.
Millions of the carnivorous mammals have been culled as a precautionary measure in Denmark, the world’s largest exporter of mink fur, with corpses buried in shallow graves. Genetic analysis of the Danish strains in the farmed mink found that the mutations were unlikely to undermine human vaccines and therapies, but several scientists backed the controversial culling to stop the uncontrolled spread by mink populations. Thousands of mink died after catching the virus, and it has been detected in wild mink during animal surveillance near a Utah mink farm.
If approved for use on mink by U.S. regulators, Kumar believes the vaccine could also benefit humans, potentially halting the emergence of new coronavirus variants that could undermine immunization efforts in humans. The company must show regulators that the vaccine has reasonable expectations for efficacy and safety, and is conducting trials with mink farmers in the US. So far, it has no blood analysis data on the vaccine’s efficacy in great apes, but has found a strong immune response in mink.
“We clearly know that the minks in Denmark were able to pass the virus back on to humans. The mink contributed a number of changes to the virus, so we are clearly concerned about the mink’s spill to humans. So by protecting the mink, it prevents the overflow into the human population, ”says Kumar.
“We make and develop vaccines for multiple animal species, including coronavirus vaccines. So we used knowledge to develop this [for Covid-19]We had several formulations that we tested on cats and dogs when we were contacted by the San Diego Zoo. “
Kumar says Zoetis has received several requests from other US zoos to use the experimental jab – similar to the Novartis human vaccine – after the great apes’ vaccinations received news worldwide. But each shot requires an emergency permit from the United States Department of Agriculture (USDA), and there are strict rules for the commercial use of the vaccine, whereby developers are only allowed to sell vaccinations for the listed species.
Zoetis, which was rolled out from Pfizer in 2013, first began developing the vaccine after pets in Hong Kong began testing positive for Covid-19, with fears that dogs and cats could be carriers for the spread of animal to human. There is no evidence that this is the case, but in the UK Vets have warned of a possible link between the Kent coronavirus strain and heart problems in cats and dogs.
In the USDA notice announcing it would accept licensing applications for mink vaccinations against Sars-CoV-2, the agency said there was very limited evidence that the disease spreads between cats and dogs in non-laboratory settings. It concluded that a Covid-19 vaccine for pets would be of no value and that it would not license species other than mink without more evidence of transmission. Kumar says Zoetis is ready if the virus changes.
“Of course we don’t want it to end up with cats and dogs. However, it is a major concern for us that if the virus were to change and mutate so that it becomes more contagious in cats and dogs, we are ready. We’re pretty sure we’ll have something very soon if something like this happened. “