Nine great apes at the San Diego Zoo - four orangutans and five bonobos - made veterinary history in recent weeks as the world's first non-human primates known to be vaccinated against Covid-19, zoo officials said on Thursday.

One of the recipients was a 28-year-old female Sumatran orangutan named Karen who had garnered headlines at the zoo when she became the first ape to undergo open-heart surgery in 1994.

Each of the nine animals received two doses of...