Rizzo Caterina, Viboud Cécile, Montomoli Emanuele, Simonsen Lone, Miller Mark A
Department of Pharmaco-Biology, University of Bari, Italy.
Vaccine. 2006 Oct 30;24(42-43):6468-75. doi: 10.1016/j.vaccine.2006.06.052. Epub 2006 Jul 7.
We investigated trends in influenza-related mortality among the elderly population in Italy associated with increased vaccination coverage. Using Italian vital statistics data, we studied monthly death rates for pneumonia and influenza and all-cause for persons >/=65 years of age by 5-year age groups for 1970-2001. Using a classic seasonal regression modelling approach, we estimated the age-specific seasonal excess mortality rates among Italian elderly as a measure of influenza-related deaths. We studied trends in excess mortality after adjusting for population aging and analyzing separately seasons dominated by the severe A/H3N2 subtype and those dominated by other circulating influenza subtypes. After the late 1980s, no decline in age-adjusted excess mortality was associated with increasing influenza vaccination distribution primarily targeted for the elderly. These findings suggest that either the vaccine failed to protect the elderly against mortality (possibly due to immune senescence), and/or the vaccination efforts did not adequately target the frailest elderly. As in the US, our study challenges current strategies to best protect the elderly against mortality, warranting the need for better controlled trials with alternative vaccination strategies.
我们调查了意大利老年人群中与疫苗接种覆盖率提高相关的流感相关死亡率趋势。利用意大利的人口动态统计数据，我们研究了1970年至2001年期间65岁及以上人群按5岁年龄组划分的肺炎和流感以及全因的月度死亡率。采用经典的季节性回归建模方法，我们估计了意大利老年人中特定年龄的季节性超额死亡率，以此作为流感相关死亡的衡量指标。我们在调整人口老龄化因素后研究了超额死亡率趋势，并分别分析了以严重的A/H3N2亚型为主导的季节和以其他流行流感亚型为主导的季节。20世纪80年代后期以来，针对老年人的流感疫苗接种分布增加，但年龄调整后的超额死亡率并未下降。这些发现表明，要么疫苗未能保护老年人免受死亡影响（可能由于免疫衰老），和/或疫苗接种工作没有充分针对最体弱的老年人。与美国一样，我们的研究对当前旨在最佳保护老年人免受死亡影响的策略提出了挑战，这就需要进行更好的对照试验，采用替代的疫苗接种策略。
