30 Influenza 2006

during an ongoing epidemic or pandemic, especially in our highly mobile and densely populated world.

Epidemic Prophylaxis

Exposure Prophylaxis

Basic personal hygiene measures, invented more than a century ago, are still the cornerstones of prophylaxis. Physicians should encourage regular hand-washing among family members of patients. In general, people should be discouraged to touch their eyes nose or mouth. Minimise the impact of sneezes and coughs by all possible means (WHO 2006a).

Vaccination

Vaccination against influenza viruses is the second cornerstone in preventing influenza. Vaccination in the northern hemisphere is recommended to start in October. Recommendations regarding the composition of the vaccine are issued yearly on the basis of detailed investigations of circulating strains. Vaccination against the prevalent wild-type influenza virus is recommended for all individuals in high-risk groups, including those aged 65 years or older (CDC 2005), and those with chronic illness, particularly diabetes, chronic respiratory and cardiac disease, and persons immunocompromised from disease or concomitant therapy. In addition, it is generally recommended that all healthcare personnel be vaccinated annually against influenza (CDC 2006b). The rate of influenza vaccination depends on a number of variables, including explicit physician recommendation and media coverage (Ma 2006).

In healthy primed adults, the efficacy after one dose may be as high as 80-100 %, while in unprimed adults (those receiving their first influenza immunisation), efficacy is in this range after two doses. With some underlying conditions (i.e., HIV infection, malignancies, renal transplantation), efficacy is lower (Korsman 2006); however, protection ultimately depends on who is vaccinated and on the match between the vaccine and the circulating virus (Wong 2005).

The evidence of efficacy and effectiveness of influenza vaccines in individuals aged 65 years or older has recently been reviewed. Well matched vaccines prevented hospital admission, pneumonia, respiratory diseases, cardiac disease, and death. The effectiveness is better in people living in homes for the elderly than in elderly individuals living in the community (Jefferson 2005). Inactivated vaccine reduces exacerbations in patients with chronic obstructive pulmonary disease (Poole 2006). Influenza vaccines are efficacious in children older than two years but little evidence is available for children under two (Smith 2006). Nasal spray of live vaccines seemed to be better at preventing influenza illness than inactivated vaccines.

Antiviral Drugs

In selected populations, antiviral drugs may be a useful option in those not covered or inadequately protected by vaccination. It should be emphasised, though, that the prophylactic use of available antiviral drugs is by no means a substitute for the yearly vaccination recommended by national health services.