It's not to be sneezed at - flu is spread by breathing
Merely breathing out is enough to spread the flu virus, according to new research.
Even without an infected person sneezing and coughing, the virus - which has already led to 24 deaths in Ireland this season - can spread, and pose a risk to others.
The findings in the 'Proceedings of the National Academy of Sciences' said people with flu generate infectious aerosols - tiny droplets that stay suspended in the air for a long time, particularly during the first days of illness.
It reinforces the need for people who have flu symptoms to stay at home and remain out of the workplace.
They assessed the flu virus in 142 individuals who were confirmed to have the illness.
They took samples from each participant during the first three days after their symptoms emerged and were able to use viable data from 218 samples of exhaled breath and 218 "nasopharyngeal swabs", where samples are taken through the nose or the back of the nose and throat.
The samples of exhaled breath included samples taken during natural breathing, spontaneous coughs, and sneezes.
Nearly half had traces of infectious virus.