Flu Transmission via hands and surfaces

While most people are aware that colds and flu are transmitted from person to person via coughing and sneezing there is less awareness that people can catch flu and colds through other forms of direct and indirect contact.

One of the pre-requisites in preparing the public for any pending pandemic will be to greatly increase public awareness of these forms of transmission and effective measures for controlling them.

Influenza is of course highly contagious, in particular for those who don't have any pre-existing antibodies against influenza obtained through previous viral exposure. This will typically include young children during inter-pandemic phase influenza and almost everyone during a highly mutated viral pandemic.

Commonly around 50% of all "normal" influenza infections are asymptomatic and this is particularly common in children. Most influenza virus is transmitted via droplets through the coughing and sneezing of infected persons. It can however also be transmitted by direct and indirect contact and many people seem unaware of this.

Direct-contact transmission involves skin-to-skin contact and the physical transfer of the virus to a susceptible person from an infected person.

Such direct contact transmission can occur in a hospital or care setting for example as staff perform patient care activities involving physical contact. Direct-contact transmission in these settings can also occur between two patients (e.g., by hand contact). In domestic settings when people fall ill, awareness of contact transmission will be less and the risks of this route may be higher.

Indirect-contact transmission involves a contaminated intermediate object, usually inanimate, in the infected persons environment. There is some evidence that flu virus can survive outside the human body for some time. The infected persons may contaminate a surface through coughing , sneezing or hand contact ( if hands have come into contact with mouth or nose). Another person touching this surface with their hands may then transfer this infection to themselves through hand to face contact. (There have been suggestions that influenza can even infect through the eye membranes).

There is insufficient data to exactly determine the proportion of influenza transmission that is attributable to direct or indirect contact.

So apart from being actually coughed or sneezed upon by an infected person, the most common way to catch the flu is by touching something which has been coughed on or sneezed upon by an infected person. The person who used that door handle before you had the flu. They covered their mouth with their hand as they coughed then used that same hand to open the door. You touch the same place and without thinking later rub your eye or nose. You have introduced the virus to your most vulnerable point of infection.

Good hand washing practice and awareness of such transmission routes is vital.
Droplet transmission is still thought the predominant overall form of spread particularly in a setting such as a crowded space where air exchange is limited. However contact transmission should always be controlled for.

Good hand washing practice should involve the use of reliable soaps and/or wipes.