The scientific community has never sought to develop a vaccine as rapidly as it is pushing for a coronavirus vaccine. In an effort to make progress at lightning speed, researchers are turning to animals for answers.
Ferrets, monkeys, and hamsters stand at the forefront of the quest to create an effective and long-lasting COVID-19 vaccine. Ralph Baric, a coronavirus expert at the University of North Carolina, Chapel Hill, calls it “a great experiment.”
How Can Animals Support Vaccine Development Efforts?
According to Kate Broderick, research chief at Inovio Pharmaceuticals, animal testing allows scientists to witness how the body reacts to vaccines in ways human studies simply cannot.
“We’re able to perform autopsies and look specifically at their lung tissue and get a really deep dive in looking at home their lungs have reacted,” Broderick explains of the animals. No animal species perfectly mimics human infection, so it’s important for researchers to test multiple animals at once and compare the results.
What Do Animal Results Show?
Early animal testing results indicate no signs of disease enhancement, a side effect that sometimes occurs when a vaccine doesn’t properly stimulate the immune system. In some aggressive cases of disease enhancement, the vaccine not only fails to produce antibodies that block infection, but it actually makes any resulting disease even worse. Fortunately, there’s no evidence that the coronavirus vaccine candidates under development pose a risk for disease enhancement.
Instead, researchers across the globe have observed interesting behaviors in the animals undergoing testing. One research team at the University of Hong Kong infected eight hamsters with COVID-19, all of which lost weight, became lethargic, and developed ruffled fur and rapid breathing. Research lead Jasper Fuk-Woo Chan reported these findings “closely resemble the manifestations of upper and lower respiratory tract infections in humans.”
Other researchers are immunizing animals with a vaccine candidate, then “challenging” the animals with exposure to the virus. Scientists can glean many pieces of essential information from such experiments:
- Dangers of COVID-19 drugs and vaccines
- Challenges of experimental vaccines against SARS-CoV-2 virus
- Transmission of virus through aerosolized particles vs larger droplets
- Virus behavior in children
Ferrets, for example, are believed to mimic the respiratory transmission of COVID-19 because they sneeze like humans.
But the most valuable animal the quest for a coronavirus vaccine appears to be the monkey. Although monkeys are more difficult to handle than mice or hamsters, their close genetic relationship to humans allows for precise, insightful results.
One Dutch study of eight monkeys infected with SARS-CoV-2 found that the oldest monkeys developed higher levels of the virus than their younger counterparts. Other studies are now staging experiments to better understand transmission risks of coronavirus.
Inovio Produces Antibodies in Animals
Inovio made headlines in May when the immunotherapy company announced its experimental coronavirus vaccine successfully produced protective antibodies and immune system responses in mice and guinea pigs.
“We saw antibody responses that do many of the things we would want to see in an eventual vaccine,” said Dr. David Wiener, director of the vaccine and immunotherapy center at the Wistar Institute, a collaborator with Inovio. “We are able to target things that would prevent the virus from having a safe harbor in the body.”
This accomplishment marks a major milestone in the use of animals for vaccine development and research.
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