H1N2 swine flu: UK's first human case recovers after mild illness

English health officials are tracing the contacts of a person in North Yorkshire who seems to have caught a flu virus from pigs called influenza A(H1N2)v, the first time such a transmission has happened in the UK.

The person had a mild illness and has since fully recovered, but public health doctors are investigating how they caught it, as viruses that cross from animals to people have the potential to cause pandemics.

However, this strain of flu has crossed from pigs to humans in other countries on 50 reported occasions since 2005, without triggering any such event.

Paul Hunter at the University of East Anglia, UK, says it is reassuring that previous infections in humans caused by this type of virus don’t seem to have been more severe than seasonal flu strains.

“It clearly needs to be kept an eye on, but I’m not particularly concerned about it,” he says. If this virus does start spreading between people, this year’s flu vaccine should give partial protection against it, he says.

The virus in the North Yorkshire case is different to the previous human cases of influenza A(H1N2), but is similar to viruses in UK pigs, says the UK Health Security Agency (UKHSA).

It was detected because the infected person consulted their family doctor, who sent a sample for testing as part of the national routine flu surveillance programme. Testing at primary care clinics and hospitals in parts of North Yorkshire has now been stepped up.

“We are working rapidly to trace close contacts and reduce any potential spread,” Meera Chand of the UKHSA said in a statement. “In accordance with established protocols, investigations are underway to learn how the individual acquired the infection and to assess whether there are any further associated cases.”

“Pig keepers must also report any suspicion of swine flu in their herds to their local vet immediately,” UK chief veterinary officer Christine Middlemiss said in a statement.

In 2009, a different flu virus called H1N1, containing genetic sequences from flu viruses that originated in pigs, birds and humans, started spreading between people, in a pandemic that became known as swine flu. That variant is now part of the range of viruses that cause ordinary seasonal flu.

A bird flu virus called H5N1 has also been causing a large flu outbreak among domestic and wild birds since 2021.