Fact Check-Chimpanzee adenovirus vector in the AstraZeneca COVID-19 vaccine does not cause monkeypox

False claims that the outbreak of monkeypox was caused by using a chimpanzee adenovirus vector in the Oxford/AstraZeneca COVID-19 vaccine have been gaining traction online.

One person on Twitter,a former member of the London Assembly, wrote on May 20: “Who is surprised that after millions of people have been injected with genetically modified chimp virus, there is now an outbreak of monkeypox?” (here). His post has since received 2,000 retweets and has been liked 6,000 times.

The same suggestion has also been echoed elsewhere on Twitter, as well as Facebook, with users highlighting a list of ingredients making up the AstraZeneca COVID-19 vaccine (here , here , here , here and here).

While it is true that the AstraZeneca vaccine uses a chimpanzee adenovirus vector in its formula (see the ingredients list here), it is not connected to monkeypox. Monkeypox is caused by the monkeypox virus, according to the World Health Organization (

“It is wholly different from Monkeypox and there is no possibility whatsoever that the two are linked,” said Ian Jones, professor of virology at the University of Reading.

He told Reuters via email: “The virus used in the AZ vaccine is an adenovirus that has been mutated to prevent it (from) growing in human cells.“

Since there is little if any immunity to it among humans, it can be used as a vaccine, or vaccine vector, he said. “All the vector does is carry the vaccine component into human cells, it does not establish any sort of infection itself.”

Jones’ words were echoed by experts at Meedan Health Desk, a group of public health scientists working to tackle medical misinformation online, who told Reuters: “Scientists use a chimpanzee adenovirus as a vector - a way to get instructions for making virus-fighting antigens into the body.” (here).

Meedan added: “It should be noted that chimpanzees are not monkeys.”

Chimpanzees are from a group of primates known as great apes, see here.

Monkeypox outbreaks in Europe and North America have raised alarm because the viral disease, which spreads through close contact and was first found in monkeys, mostly occurs in west and central Africa, and only very occasionally spreads elsewhere.

Monkeypox is a virus that causes fever symptoms as well as a distinctive bumpy rash and is usually mild. (here).

Reuters has debunked COVID-19 vaccine misinformation in the past. See here , here and here .


False. There is no link between the use of chimpanzee adenovirus vector in the AstraZeneca vaccine and monkeypox, which is caused by the monkeypox virus. Chimpanzees are not monkeys and the viruses are not related.

This article was produced by the Reuters Fact Check team. Read more about our fact-checking work here.

Advisory June 8, 2022: This piece has been corrected to reflect that the tweet on paragraph 2 was sent by a former member of the London Assembly.