Swine flu Q&A: From tell-tale symptoms to how quickly it spreads – everything YOU need to know

Britain was today rocked by fresh swine flu fears after someone was sickened by a strain never seen here before. 

Officials don’t know how the unidentified Brit got infected with H1N2, leaving some experts concerned it could be spreading under the radar. 

UK Health Security Agency (UKHSA) bosses are scrambling to contain the virus.

All contacts of the individual, who has fully recovered after a ‘mild’ illness, are being traced. 

So how deadly is swine flu? Are the symptoms any different to regular flu? And isn’t the illness already circulating through the UK? Here, MailOnline explains everything you need to know about the strain.  

What is H1N2?

H1N2 is one particular strain of swine flu. Like human influenza viruses, there are different types. 

Swine flu is usually caused by three main subtypes — H1N1, H1N2 and H3N2. 

A variant of H1N1 triggered the 2009 swine flu pandemic and killed thousands of people around the world. 

However, that specific sub-type still circulates in humans today and is no longer referred to as ‘swine flu’ because of its distinct genetic make-up. 

How deadly is it?

Only 50 human cases of H1N2 have been reported globally since 2005. 

But none of them have been in the UK. What’s more, none are related genetically to this specific strain.

Since the 2009 swine flu crisis there have been sporadic fatalities worldwide linked to viruses jumping from pigs to humans.

An independent review of the UK response to the pandemic confirmed 457 deaths were caused by swine flu in the country.

But the case fatality rate — the proportion of patients who died from the disease — was thought to have been around 0.02 per cent. For comparison, when Covid first struck, it had a fatality rate of up to three per cent.

How quickly does it spread?

It is not known at this stage how transmissible the strain is or if there could be other cases in the UK.

However, the virus only rarely spreads between humans. 

Instead, most cases occur among people exposed to infected pigs, such as visitors of country fairs and farmers.

UK Health Security Agency (UKHSA) bosses said they were ‘working rapidly to trace close contacts and reduce any potential spread’.

Where is it spreading?

The case was identified after the Brit, who’s thought to live in north Yorkshire, tested positive after visiting their GP with ‘respiratory symptoms’.

But health chiefs have not yet found the source of the infection and have opened an investigation, the UKHSA said. 

The UKHSA said it was now ‘monitoring the situation closely’ and increasing its swine flu surveillance programme involving GP surgeries and hospitals within north Yorkshire. 

They have also urged anyone with ‘respiratory symptoms’ to stay at home and avoid all contact with others until the illness has subsided. 

What are the symptoms of H1N2?

For most people, swine flu is mild. It comes on quickly and generally lasts for around a week. 

The virus often causes fever, tiredness, a cough and a sore throat. 

Other symptoms can include a headache, aching muscles, chills, sneezing, a runny nose, loss of appetite, vomiting and diarrhoea. 

But cases are normally mild and clear up on their own. Death rates are typically low.

Scientists say, however, that children under five, people over 65, pregnant women and those with underlying health conditions are more at risk of complications if they become infected.

How is it different to the 2009 swine flu outbreak? 

That variant, scientifically known as H1N1(pdm09), contained genetic material from viruses circulating in pigs, birds and humans.

Swine flu is of concern because pigs can act as ‘mixing vessels’, harbouring viruses from different species at the same time. As such, genetic material can mix to create a hybrid virus in a process called assortment.

That is what sparked the 2009 pandemic.

It is not yet known what genes the H1N2 strain circulating in Britain carries.

How does swine flu spread?

Like with any flu, when infected pigs cough, sneeze or even just breathe, droplets carrying pieces of influenza can spread through the air. 

If these land in a person’s nose and mouth, or inhaled, they can become infected.

Swine flu surges in pigs around autumn, raising the risk of the disease spilling over into humans.

The virus might survive in carrier pigs for several weeks without them showing any clinical signs. These carrier pigs can then be a source of infection for other pigs.

It can also be spread by wild animals and birds or indirectly through contaminated equipment, clothing, feed or water.

It has not been shown to be transmissible through eating pork and other products derived from pigs. Culls of pigs have occurred for similar viruses, however.

Health officials say the most effective way of reducing transmission is by following simple respiratory and hand hygiene. 

How can swine flu be treated?

Most people cannot be certain they have had swine flu without it being confirmed through laboratory tests. 

This requires PCR testing, like what was used to detect Covid.

During the 2009 crisis, people ill with swine flu were often treated with the antiviral drug Tamiflu. But follow-up analysis suggested the drug worked no better than remedies like paracetamol.

The NHS still says Brits may get Tamiflu (known as oseltamivir) or Relenza (zanamivir) in the event of catching bird flu, which is considered another variant flu threat. 

It says: ‘Antiviral medicines help reduce the severity of the condition, prevent complications and improve the chances of survival.

‘They are also sometimes given to people who have been in close contact with infected birds, or those who have had contact with infected people, for example family or healthcare staff.’