Lehmann D, Marshall T F, Riley I D, Alpers M P
Papua New Guinea Institute of Medical Research, Goroka.
Ann Trop Paediatr. 1991;11(3):247-57. doi: 10.1080/02724936.1991.11747510.
The effect of a 14-valent pneumococcal polysaccharide vaccine on morbidity from acute lower respiratory tract infection (ALRI) was determined in a randomized double-blind controlled trial in children under the age of 5 years living in the Paupa New Guinea highlands. The vaccine did not protect against mild ALRI. Vaccine efficacy in the study as a whole was 28% for moderate/severe ALRI, which was not statistically significant though consistent with the significant effect on mortality. Children entered the trial in five separate cohorts 4 months apart. The incidence of disease and vaccine efficacy varied between cohorts and with age. There was no vaccine effect in the first cohort, which had a much higher proportion of older children. The effect was greatest and statistically significant among those groups encountering an epidemic of moderate and severe ALRI at a young age. It was therefore in children at the most vulnerable age in times of greatest incidence of disease that the vaccine had its most potent effect. It is postulated that the efficacy of pneumococcal vaccine is dependent on the predominant invading serotypes in the period after vaccination, the age at which children develop immunocompetence to specific vaccine serotypes, and the levels of naturally acquired specific immunity already present in children at the time of vaccination, and that for all of these conditions there will be a cohort effect.
在巴布亚新几内亚高地开展的一项针对5岁以下儿童的随机双盲对照试验中，确定了14价肺炎球菌多糖疫苗对急性下呼吸道感染（ALRI）发病率的影响。该疫苗不能预防轻度ALRI。在整个研究中，该疫苗对中度/重度ALRI的效力为28%，虽与对死亡率的显著影响一致，但无统计学意义。儿童分五个独立队列、每隔4个月进入试验。疾病发病率和疫苗效力在各队列之间以及随年龄有所不同。在第一个队列中没有疫苗效果，该队列中年龄较大儿童的比例要高得多。在那些幼年时遭遇中度和重度ALRI流行的组中，疫苗效果最大且具有统计学意义。因此，在疾病发病率最高时处于最脆弱年龄的儿童中，该疫苗具有最显著的效果。据推测，肺炎球菌疫苗的效力取决于接种疫苗后一段时间内主要侵袭血清型、儿童对特定疫苗血清型产生免疫能力的年龄，以及接种疫苗时儿童已有的自然获得性特异性免疫水平，并且对于所有这些情况都将存在队列效应。
