The Health Security Agency said Tuesday that two people who work with poultry in the U.K. tested positive for bird flu, but they didn’t have any symptoms and there’s no proof that it spreads from person to person.

The two people are the first people in the U.K. to test positive for the virus since a 79-year-old English man was sick after he let ducks into his home.

The agency said that the avian flu had only been passed from birds to people in the U.K. a few times before that January 2022 case.

Workers in the poultry industry who tested positive for the H5 strain were thought to have been around sick birds at the same farm, which could not be found.

After avian flu was found on dozens of farms, all birds on poultry farms had to stay inside from November until mid-April. Since October 2021, the U.K. has had its worst avian flu outbreak, with hundreds of proven cases and millions of birds being killed.

Through screening poultry employees who had contact with diseased birds, the positive tests were found. The two employees tested negative after that.

According to the agency, precautionary contact tracing was being done.

The amount of risk to human health from bird flu was very low in the general population, according to Susan Hopkins, the agency’s chief medical adviser.

According to Hopkins, “current evidence suggests that the avian influenza viruses we are seeing circulating in birds around the world do not easily spread to people.” Although there isn’t any proof of this strain spreading from person to person anywhere in the world, we know that viruses change all the time and are constantly on the lookout for any indications of shifting population danger.