Each year, influenza viruses circulate worldwide and are responsible for a considerable burden of medical visits, hospital admissions, and deaths. Older adults (aged ≥65 years) are more susceptible to influenza illness than younger adults and are less likely to benefit from preventive measures such as vaccination because of the increased prevalence of chronic conditions and the degeneration of immune functioning at older ages.¹ Although influenza vaccines have been used since the 1940s, and the WHO recommends vaccinating older adults, evidence on vaccine efficacy in this age group is scarce, and there are several reports of decreased immunogenicity and vaccine effectiveness in older adults compared with younger adults.

中文翻译：

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热带和亚热带地区的流感疫苗接种

每年，流感病毒在世界范围内传播，并造成相当大的医疗就诊，住院和死亡负担。老年人（≥65岁）比年轻人更容易感染流感，并且由于慢性病患病率增加以及老年人免疫功能下降，因此不太可能受益于预防措施，例如疫苗接种。¹尽管自1940年代以来就已使用流感疫苗，并且WHO推荐给老年人接种疫苗，但在这一年龄组中疫苗效力的证据很少，并且有几项报道表明，与年轻人相比，老年人的免疫原性和疫苗效力降低。