(CNN)Several great apes at the San Diego Zoo have been vaccinated against Covid-19 a few weeks after the zoo's gorillas tested positive for the virus.
Members of the zoo's bonobo and orangutan troops were vaccinated using doses from a supply intended strictly for non-human use, the San Diego Zoo Wildlife Alliance (SDZWA) said in statement to CNN.
Veterinarians for the SDZWA, the nonprofit that oversees the San Diego Zoo and San Diego Safari Park, identified members of the bonobo and orangutan troops most at risk who could be easily vaccinated, the organization said.
Vaccinations began in January and have continued up to this month, and the animals received their second dose after three weeks.
"The animals are doing well and we have seen no adverse reactions from the vaccine. The wildlife in our care is closely monitored throughout their lives," said Darla Davis, a SDZWA spokeswoman.
In January, eight of the San Diego Zoo Safari Park's gorillas caught the virus, though their symptoms were mild and limited to coughing, congestion and fatigue. The troop has since fully recovered.
"The gorilla troop at the Safari Park did not receive the vaccine as they were exposed to the SARS-CoV-2 virus, and we assume their own immune systems have developed antibodies to the virus," Davis said.
Most coronavirus cases among animals have occurred in domestic pets like dogs and cats, but animals in zoos have been diagnosed, too, likely after contact with infected zookepers.
In April, several tigers and African lions at the Bronx Zoo tested positive for coronavirus, and snow leopards at the Louisville Zoo in Kentucky caught the virus in December.
A small number of dogs and cats in the United States have been infected with the virus, according to the Centers for Disease Control and Prevention. In most animal cases, coronavirus isn't deadly, though coronavirus outbreaks at fur farms in the US and abroad have killed thousands of mink.
It's unlikely the leopards -- or other animals -- pose a significant risk in transmitting the virus to humans, as Covid-19 is primarily spread between people.