At a glance
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Rabies still kills tens of thousands of people each year, mostly in Africa and Asia, and nearly all human cases are linked to dog bites.
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A study in PLOS Neglected Tropical Diseases finds that SPBN GASGAS, an oral rabies vaccine placed inside edible baits for dogs, appears safe for both animals and people, even if humans come into contact with the vaccine virus.
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Used alongside traditional injectable vaccines, oral vaccination of free-roaming dogs could help countries reach herd immunity and eliminate dog-mediated rabies.
A new study suggests that delivering rabies vaccine to dogs through edible baits—rather than by syringe—could become a powerful tool in the global effort to eliminate rabies spread by dogs.
For decades, oral rabies vaccination has played a major role in controlling the disease in wildlife, helping remove rabies from fox and raccoon populations across large parts of Europe and North America.
Yet 99% of human rabies deaths are linked not to wild animals, but to dogs.
To tackle the problem at its source, Ceva Santé Animale, a France-based animal health company, has registered an oral rabies vaccine designed for use in free-roaming and street dogs that are difficult to catch and inject.
In PLOS Neglected Tropical Diseases, Dr. Gowri Yale, Global Rabies Programme Director at Ceva Santé Animale, and her colleagues present a detailed human safety assessment of SPBN GASGAS, a third-generation oral rabies vaccine developed specifically for dogs.
Drawing on three decades of laboratory, regulatory, and field data, the researchers found that even if people come into contact with the vaccine virus—through a leaking bait or a recently vaccinated dog—there are no safety concerns.
Rabies remains a serious public health issue in Africa and Asia, causing tens of thousands of deaths every year. About 40% of those deaths occur in children under 15. Once rabies symptoms appear, the disease is almost always fatal.
Yale believes oral vaccines could make a major difference. They can “increase coverage with ease and quickly without chasing dogs.”
She adds that administering the vaccine does not require advanced technical skills. Field workers can be trained to use oral rabies vaccines in a day or two.
“Additionally, oral rabies vaccines provide very long-lasting immunity, helping maintain herd immunity and making elimination achievable. This helps countries reliably reach the critical 70% immunity needed to stop rabies transmission,” she said.
Testing safety
SPBN GASGAS is a genetically engineered version of the long-used SAD B19 vaccine strain, modified to prevent the virus from causing harm.
Extensive testing in dogs, foxes, and mongooses—as well as non-target animals including cats, skunks, and pigs—showed no serious adverse effects, even when animals received high doses, repeated doses, or the vaccine through different routes.
Researchers also found that the vaccine virus is not actively shed by vaccinated animals and does not spread beyond the point where it enters the body. There was no transmission from vaccinated pregnant animals to their offspring.
Because live vaccines that replicate can theoretically mutate back into a harmful form, the team repeatedly grew the vaccine virus in cell cultures and in highly susceptible mouse brain tissue, followed by full genome sequencing.
After five rounds of testing, the key safety mutations remained stable. No return to virulence was observed when the virus was injected into adult mice.
To model what might happen if immunocompromised people came into contact with the vaccine, scientists tested it in immunocompromised mice. The vaccine remained safe when given orally or under the skin. Illness occurred only when the virus was injected directly into the brain—an extreme exposure route that would not occur in real-world use.
The final mile
Because oral rabies vaccination has already helped eliminate wildlife rabies in parts of Europe and North America, Yale says the potential for eliminating dog-mediated rabies in low- and middle-income countries is significant.
“If oral rabies vaccines are rolled out at scale alongside existing tools, the problem is solved—rabies is removed at its source, which is free-roaming dogs,” she said.
Although oral vaccines cost more per dose than injectable ones, the overall costs may be lower. Injectable campaigns require large teams, trained staff to safely restrain dogs, and vehicles to transport equipment and personnel.
In contrast, oral vaccination can often be carried out by small teams—sometimes just two people on a motorbike—without needing to handle dogs or rely on advanced technical skills.
The way vaccine baits are distributed is also important. The researchers recommend a “hand-out and retrieve” approach, in which trained workers give the bait directly to dogs and collect any leftovers. This method reduces the risk of human contact compared with giving baits to owners or scattering them in the environment.