Researchers have found that we can pass on the flu just by breathing normally
It had been thought the illness was transmitted via watery droplets expelled into the air as coughs or sneezes.
But experts have discovered we can pass on the virus just by normal breathing, especially in the first few days of being infected.
And they warn it is not enough to simply wash our hands and work surfaces or avoid someone spluttering on the train or in the office.
To avoid catching a dose of the flu, the only way would be to send those coming down with flu home, avoid public places during the flu season or get the flu jab.
Flu cases have risen by over 150% in the UK this year, and at least 120 deaths have been recorded
We found that flu cases contaminated the air around them with infectious virus just by breathing, without coughing or sneezing.
Researchers said the findings shed new light on the importance of airborne transmission because of the large quantities of infectious virus being exhaled from people suffering from flu.
It comes as the UK is hit by rising levels of flu cases with GPs reporting an increase of over 150 per cent in cases since the start of the year with at least 120 deaths so far this winter.
Flu cases have soared more than two and a half times in just a fortnight – fuelled by the deadly ‘Australian’ strain. About 31,300 patients in England visited their GP last week – a rise of almost 153 per cent since the start of the year.
The worst hit regions include Birmingham, Norwich, Nottingham, Manchester, York, Newcastle, Bristol, Portsmouth and Canterbury.
31,300 patients in England visited their GP due to flu last week
Health officials have renewed their pleas for people to have the flu jab with 8.3 million suffering flu-like symptoms.
The crisis is adding extra pressure onto an already stretched NHS, which is considered to be in the middle of its worst winter on record.
Commenting on the research, Professor Dr Donald Milton at the University of Maryland School of Public Health in the US said: “We found that flu cases contaminated the air around them with infectious virus just by breathing, without coughing or sneezing.
“People with flu generate infectious aerosols – tiny droplets that stay suspended in the air for a long time – even when they are not coughing, and especially during the first days of illness.
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“So when someone is coming down with influenza, they should go home and not remain in the workplace and infect others.”
The study involved putting 142 students with flu inside a machine 30 minutes on the first, second, and third days after the onset of symptoms.
The machine captured what they expelled when breathing, talking, spontaneously coughing and sneezing and the infectivity of naturally occurring influenza aerosols was assessed.
Analysis showed a significant number of flu patients routinely shed infectious virus into aerosol particles small enough to present a risk for airborne transmission.
The most prevalent strain of flu in the UK is influenza B, which includes H3N2 or ‘Aussie flu’
Professor Sheryl Ehrman at San Jose State University in California added: “The study findings suggest that keeping surfaces clean, washing our hands all the time, and avoiding people who are coughing does not provide complete protection from getting the flu.
“Staying home and out of public spaces could make a difference in the spread of the influenza virus.”
The study was published in the Proceedings of the National Academy of Sciences.
Professor Helen Stokes-Lampard, Chair of the Royal College of General Practitioners, said: “General practice continues to face huge winter pressures with a significant increase in patients presenting with influenza, and high numbers of patients continuing to present with other common winter illnesses.
“The best prevention for flu, other than observing good hygienic practices, such as regular hand washing, is for people, particularly those in at-risk groups, including patients with long-term conditions and pregnant women, to get their flu jab.
“It is not too late to receive some benefit from vaccination.
“If someone does have the flu, unfortunately there is no cure, but patients can assist their own recovery through taking plenty of rest and drinking lots of fluids.”
The latest statistics suggest around 4,500 people were admitted to hospital with flu last week.
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The most prevalent strain is influenza B which includes H3N2, or ‘Aussie flu’, which is thought to have claimed the life of Bethany Walker, from Applecross in the Scottish Highlands, earlier this month.
A spokeswoman for Public Health England (PHE) said: “We’re right into flu season now but there’s still time to be vaccinated.”
PHE figures show there were 17 flu-related deaths during the second week of the year alone.
Dr Nick Scriven, president of the Society for Acute Medicine, warned the strain on already-stretched services could last for many more weeks, putting NHS staff at risk of getting ill themselves.