Improved hand hygiene is known to reduce transmission of both respiratory (RTI) and gastrointestinal infections (GTI) under "semi-closed" conditions such as hospitals, day-care centres and schools. It is not known if similar interventions would have the desired effect in a regular office work. This study is aiming to investigate this possibility by recruiting volunteers from several companies in the Helsinki Region. The two intervention groups will receive detailed instructions e.g. for proper coughing and sneezing, and for regular cleaning of hands with either standard liquid soap or with alcohol-based gel rubbing. Third group will serve as the control and is advised not to change their previous behaviour in this respect. The participants will report weekly possible RTI or GTI symptoms and related days off through internet. The study is planned to run about 18 months to cover the seasonal variation of the epidemics of the causative different viruses.

It is common knowledge that both respiratory tract infections (RTI) and gastrointestinal infections (GTI) cause a large part of short periods of days off from work, day care and school. In addition, because of the generally mild nature of the diseases, especially adults often come to work in spite of symptoms, and may therefore initiate transmission of infection among their colleagues. The chain of events from exposure to a pathogenic virus to subsequent infection and staying home because of infectious disease is a very complicated one, and is affected by many factors potentially causing variation, such as the multitude of causative agents, different individual histories of infections, variability of inter-personal contacts in work and various working- team feelings -influenced thresholds for staying home etc. Therefore, we aim to recruit at least 24 operationally distinct volunteer groups, each including at least 50 persons, and to continue the intervention about 18 months.

A virus transmission "risk-index" will be calculated for each group based on potential participant questionnaires enquiring, among other things, about numbers and ages of children, their possible out-of-home day care, personal properties such as smoking, chronic diseases, and potential differences in contacts during daily work. The 24 groups will be divided in groups of three most similar ones, and members each triplet then randomised in one the intervention groups or the control (see brief summary).

Data collection is based on self-reporting through Monday-morning electronic reports using a standard form. The from is enquiring about possible exposure to persons suffering from RTI or GTI, and possible own symptoms of the same diseases during the preceding 7 day period (including weekends and other holidays). The form will require daily records offering all possible combinations of the following categories: healthy-with symptoms, working normally-day off, own disease-child ill-other reason for day off.

Etiology of the symptoms will not be searched for on individual basis in this study but a connection to RTI virus epidemiology is built by a sentinel surveillance, where occupational health clinics located in the premises of the participating companies send a standard number of weekly specimens collected from employees visiting the clinic. For possible GTI outbreaks a standard outbreak investigation principle will be followed, including 3-5 specimens. from typical patients will be collected. Common causative agents of the diseases will be searched for using real-time PCR techniques.

Inclusion Criteria:

• Volunteers working in defined units

Exclusion Criteria:

• Persons with open wounds or chronic eczema in hands

Entire follow up period of 16 months

In a pre-study interview, 90% stated "when I have cold I usually come to work if I only can". Participants in the intervention arms, but not those of the control arm, were advised to stay home when sick: possible contribution to outcome measure 1.