A new strain of swine flu has been detected in humans for the first time in the UK, picked up via routine testing by the patient’s GP.
The UK Health Security Agency (UKHSA) will now ‘increase surveillance’ at GP surgeries in this area.
There have been 50 human cases of the influenza A(H1N2)v strain globally since 2005, but this is the first case in the UK.
The patient was tested by their GP after experiencing respiratory symptoms, and the swine flu strain was picked up by UKHSA and the RCGP’s routine national flu surveillance.
While the patient has made a full recovery after a mild illness, close contacts are being offered testing by UKHSA.
The agency has not yet discovered the source of the infection and continues to investigate.
Its statement yesterday said: ‘UKHSA is monitoring the situation closely and is taking steps to increase surveillance within existing programmes involving GP surgeries and hospitals in parts of North Yorkshire.
‘To assist in the detection of cases and assessment of transmission, those people who are contacted and asked to test are encouraged to do so.’
Professor Peter Openshaw, professor of experimental medicine at Imperial College London, said that without evidence that the virus is transmitted between humans, this first detection in the UK is ‘not particularly worrying’ and ‘shows surveillance is working’.
Dr Ed Hutchinson, senior lecturer at the University of Glasgow Centre for Virus Research, said viruses are ‘heavily dependent on their hosts’ and they ‘usually find it hard to infect a different host species to the one they’re used to’.
He said: ‘Influenza A viruses are (by virus standards) unusually good at infecting a wide range of different species, but even they struggle at replicating in a new host species.
‘A virus that jumps into a new host – for example from a pig into a human – usually doesn’t spread any further, causing what we call a ‘spillover infection.’
‘Because a spillover infection won’t spread more widely, this is mainly a concern if it makes the infected person ill: it’s good to know that in this case the individual recovered after a mild illness.
‘However, it is very important to monitor spillover infections. This is because, on very rare occasions, these spillover viruses can become good enough at growing in their new human host to begin spreading from human to human.
‘Very occasionally, this creates a new human-adapted virus that could cause a pandemic – although it is important to be clear that this report does not suggest that this particular spillover virus had got anything like that far.’
The influenza A(H1N2)v is one of three ‘major subtypes’ of swine influenza viruses found in pigs and occasionally in humans. This infection is usually caused by direct or indirect exposures to pigs or contaminated environments.
In 2009, a pandemic was caused by a different strain of swine flu in humans but this strain now circulates seasonally and is different to viruses currently found in pigs.
UKHSA urged vulnerable patients to come forward for their influenza jabs last month, highlighting that more people died from flu than Covid-19 last winter.