If everyone were to wash their hands the risk of colds, flu and even bird flu would be much less, say UK experts.
Professor John Oxford, of London's Queen Mary's School of Medicine, warns many people are failing to do so and are complacent about personal hygiene.
Clean hands are key to cutting infections, say experts
His team looked at the most effective methods to prevent the transmission of colds and flu, including bird flu.
Rather than relying on products such as antiviral tissues, personal cleanliness should be a priority, they say.
Hand cleaning came out top, followed by disinfecting surfaces.
The least effective way to prevent transmission of the common cold is through the use of virucidal nasal tissues, Professor Oxford and colleague Dr Rob Lambkin, also from Queen Mary's, concluded.
Studies have shown that viruses can survive on human hands for several hours and that they can be spread by direct contact.
As well as through coughs and sneezes, a person may pick up the virus on their fingers by touching an infected object or person.
Breaking the chain
If they then rub their nose or eyes with their virus-contaminated fingers they can become ill themselves and spread the infection to others, leading to a vicious cycle.
The UK experts say the best way to break the chain is for people to wash their hands.
Professor Oxford said: "Unfortunately, personal cleanliness and hygiene levels have dropped steadily over the last decades with many microbes, as never before, using the opportunity to spread.
"First and foremost to reduce virus transmission attention must be paid to hand washing and then when this is satisfactory, focus on cleansing surfaces and equipment shared by others such as desks, tables, telephones and door knobs."
He said it was important that people did not come to rely on antiviral tissues to reduce the spread of viruses and then reduce hand washing as this could lead to an increase in infection of what could be very serious respiratory viruses.
"Quite rightly for influenza, great reliance continues to be placed on vaccines and antiviral drugs, but still virus destruction on surfaces and hand washing continues to be an important adjunct."
Dr Mark Britton, chairman of the British Lung Foundation, said: "It is absolutely reasonable what they are saying. People need to be reminded about the importance of basic hand hygiene.
COMMON HOME SURFACES THAT CAN HARBOUR VIRUSES (in descending order of risk)
Toilet flush handle
Source: Journal of Infection, August 2005, pages 103-9
"This is a very sensible precaution that should be taken, especially as we approach winter and colds and viruses are likely to be emerging."
Dr Graham Archard, of the Royal College of General Practitioners, said improved hygiene would help prevent flu, but added that it was also important for those at high risk - such over 65 years old - to be vaccinated against the influenza virus.
Professor Ron Eccles of the Common Cold Centre in Cardiff said: "The only way to avoid catching a cold is to become a hermit.
"If you are in contact with other people you are likely to get a cold as the viruses are so common."
He said the best way a person could reduce the risk of catching a cold was to:
- wash hands regularly, especially after being in crowded places
- use a tissue thick enough so that it won't break apart when blowing their nose and dispose of it after use
- keep their hands away from their nose and mouth