New Respiratory Viruses and the Elderly

Jartti, Laura; Langen, Henriikka; Söderlund-Venermo, Maria; Vuorinen, Tytti; Ruuskanen, Olli; Jartti, Tuomas

The most severe epidemics have been caused by the influenza A virus. In 1918-1919 the H1N1 virus pandemic resulted in an estimated 50 to 100 million deaths [29] . The mortality was surprisingly high among young adults. The most recent pandemics have usually been caused by the influenza A virus strain H1N1 and H3N2. The 2009 H1N1 virus was highly contagious from human to human [30, 31] . In USA, the prevalence of H1N1-associated deaths was 12 deaths per 100 000 population. Of these, only 9% occurred in persons aged ! 65 years [31] . Similarly, H5N1 which had its source in birds, has infected humans since 1997, and has, by March 2011, been associated with high mortality; of 528 patients with confirmed disease, 311 (59%) have died [13, 30, 32, 33] . The mortality rate associated with H5N1 infection has been 89% among children aged <15 years [32] . Elderly are often protected by pre-existing antibodies from previous illnesses, maybe even decades back [28, 30, 31] . On the other hand, the risk of severe illness is markedly increased by underlying medical conditions, especially chronic obstructive and other pulmonary diseases, immunosuppression, diabetes, obesity, or chronic heart conditions, which often accompany old age.