Sutter R W, Patriarca P A, Brogan S, Malankar P G, Pallansch M A, Kew O M, Bass A G, Cochi S L, Alexander J P, Hall D B
Division of Immunization, Centers for Disease Control, Atlanta, Georgia 30333.
Lancet. 1991 Sep 21;338(8769):715-20. doi: 10.1016/0140-6736(91)91442-w.
From January, 1988, to March, 1989, a widespread outbreak (118 cases) of poliomyelitis type 1 occurred in Oman. Incidence of paralytic disease was highest in children younger than 2 years (87/100,000) despite an immunisation programme that recently had raised coverage with 3 doses of oral poliovirus vaccine (OPV) among 12-month-old children from 67% to 87%. We did a case-control study (70 case-patients, 692 age-matched controls) to estimate the clinical efficacy of OPV, assessed the immunogenicity of OPV and extent of poliovirus spread by serology, retrospectively evaluated the cold chain and vaccine potency, and sought the origin of the outbreak strain by genomic sequencing. 3 doses of OPV reduced the risk of paralysis by 91%; vaccine failures could not be explained by failures in the cold chain nor on suboptimum vaccine potency. Cases and controls had virtually identical type 1 neutralising antibody profiles, suggesting that poliovirus type 1 circulation was widespread. Genomic sequencing indicated that the outbreak strain had been recently imported from South Asia and was distinguishable from isolates indigenous to the Middle East. Accumulation of enough children to sustain the outbreak seems to have been due to previous success of the immunisation programme in reducing spread of endemic strains, suboptimum efficacy of OPV, and delay in completing the primary immunisation series until 7 months of age. Additionally, the estimated attack rate of infection among children aged 9-23 months exceeded 25% in some regions, suggesting that a substantial proportion of fully vaccinated children had been involved in the chain of transmission.
1988年1月至1989年3月，阿曼发生了1型脊髓灰质炎广泛暴发（118例）。尽管最近的免疫规划已将12月龄儿童3剂口服脊髓灰质炎病毒疫苗（OPV）的接种覆盖率从67%提高到了87%，但2岁以下儿童的麻痹性疾病发病率最高（87/100,000）。我们开展了一项病例对照研究（70例病例患者，692名年龄匹配的对照），以评估OPV的临床疗效，通过血清学评估OPV的免疫原性和脊髓灰质炎病毒的传播程度，回顾性评估冷链和疫苗效力，并通过基因组测序寻找暴发毒株的来源。3剂OPV可将麻痹风险降低91%；疫苗失败无法用冷链故障或疫苗效力欠佳来解释。病例和对照的1型中和抗体谱几乎相同，表明1型脊髓灰质炎病毒广泛传播。基因组测序表明，暴发毒株最近从南亚传入，与中东本土分离株不同。能够维持暴发的足够多儿童的积累似乎归因于免疫规划先前在减少地方性毒株传播方面的成功、OPV效力欠佳以及将基础免疫系列完成时间推迟至7月龄。此外，在一些地区，9至23月龄儿童的估计感染发病率超过25%，这表明很大一部分完全接种疫苗的儿童参与了传播链。
