H1N1 Influenza Pandemic in Italy Revisited: Has the Willingness to Get Vaccinated Suffered in the Long Run?

Ludolph, Ramona; Nobile, Marta; Hartung, Uwe; Castaldi, Silvana; Schulz, Peter J.

Influenza is an annually recurring, contagious viral respiratory infection that usually hits countries with temperate climate during the winter season. 1 An influenza infection poses a serious health threat especially to known risk groups such as elderly people and pregnant women. But also the large number of mild to moderate infections cause remarkable economic costs and have a direct impact on the affected peoples' daily life. 1 However, due to different, incomplete or unreliable reporting, the true morbidity and premature mortality caused by influenza epidemics is hard to assess. 2 The prediction of the medical and economic consequences of an influenza pandemic is even more difficult as the level of uncertainty is higher. There are various effective possibilities to prevent an influenza infection such as regular hand washing, the avoidance of larger gatherings of people or air travelling. The most effective prevention tool is, however, vaccination. 1, 3 Although seasonal influenza clearly depicts a burden for a country's health care system it is still relatively well manageable as the time of occurrence is foreseeable and the consequences calculable. Pandemic influenza, in contrast, happens rarely but has the potential to cause considerable damage on a national and global level. That is because of several differences between seasonal and pandemic influenza: Since the latter one only spreads a couple of times during a century most people have little or no immunity against the virus due to the missing previous exposure, whereas most people have at least some immunity against the seasonal influenza virus. 4 Moreover, pandemic influenza cannot only lead to severe complications for at high risk populations such as elderly or people with a weak immune system but also for healthy adults. 4 Due to the rapid spread of pandemic influenza, which has become even faster because of the increased rate of air travelling nowadays, countries have only little time to get prepared for the high number of cases which might likely lead to an overwhelming of their health care system. While there is mostly an effective flu vaccine against the seasonal influenza available, the strain of a pandemic influenza cannot be foreseen. Thus, it takes some time to develop a vaccine and in the meantime health authorities have to rely on nonpharmaceutical preventive measures which results in a longer timeperiod needed for the virus's containment. The combination of these factors and a usually high number of cases further causes considerable public concern -often heated up by intense media coverage. Thus, the management of pandemic influenza represents a high challenge for governments and health authorities and calls for a solid preparedness plan in order to meet the needs of the population.