Global Immunization Division, Center for Global Health, CDC, Atlanta, USA.
Vaccine. 2013 Oct 1;31(42):4911-6. doi: 10.1016/j.vaccine.2013.06.106. Epub 2013 Jul 24.
A serosurvey to evaluate population immunity to polioviruses (PVs) in the context of the importation-related wild PV1 outbreak in Tajikistan in 2010 (461 confirmed cases among children and young adults) was conducted.
Serum specimens from a nationwide sample of 1-24 year-old persons selected through stratified cluster sampling (n=2447) were tested for neutralizing antibodies to all three PV types. Samples with titers<1:8 were considered seronegative. The serosurvey was conducted during the interval after mOPV1 supplementary immunization activities (SIAs) and before tOPV SIAs (targeting ages ≤ 15 years) implemented to control the outbreak. In the absence of pre-outbreak specimens, results for PV3 were used as a proxy for pre-outbreak PV1 immunity patterns.
Overall, PV1 seroprevalence was 98.9%, PV2 seroprevalence was 98.8%, and PV3 seroprevalence was 86.9%. PV1 and PV2 seroprevalence exceeded 95% in all age groups and regions. PV3 seroprevalence was <90% in all age groups and regions, except 15-19 year-olds (91.7%) and Dushanbe (90.0%). PV3 seroprevalence was lowest among 1-4 (82.7%) and 5-9 (84.4%) year-olds, particularly among 1-4 year-olds in Kurgan-Tube (76.3%) and RRS (80.0%) regions. Birth cohorts immunized only through routine services (ages, 1-7 years) had lower PV3 seroprevalence than birth cohorts targeted by the SIAs during 1995-2002 (8-19 years): 82.5% versus 89.3%, p<0.001.
Suboptimal (<90%) PV3 seroprevalence across wide age range suggests the outbreak resulted from accumulation of susceptibles due to suboptimal coverage over a long time period, particularly in the birth cohorts immunized only through routine services and in areas where the outbreak began (Kurgan-Tube and RRS). High PV1 seroprevalence indicates that mOPV1 SIAs with expanded target age (≤ 15 years) succeeded in closing the immunity gap and ongoing WPV1 transmission is unlikely. To accelerate outbreak control in areas which have been polio-free for long time, expanding SIA target age should be considered.
在 2010 年塔吉克斯坦与输入性相关的野生 1 型脊灰病毒（PV1）暴发期间，开展了一项血清调查，以评估人群对脊灰病毒的免疫力。该血清调查是在实施针对该暴发的 mOPV1 补充免疫活动（SIAs）和 tOPV SIAs（针对年龄≤15 岁的人群）之后，以及在全国范围内选择的 1-24 岁人群中，通过分层聚类抽样采集血清样本（n=2447），并检测血清样本中针对所有 3 种 PV 型别的中和抗体。滴度<1:8 的样本被认为是血清阴性。该血清调查是在没有暴发前的标本的情况下进行的，因此使用 PV3 的结果来替代 PV1 免疫模式的暴发前情况。
总体而言，PV1 的血清阳性率为 98.9%，PV2 的血清阳性率为 98.8%，PV3 的血清阳性率为 86.9%。所有年龄组和地区的 PV1 和 PV2 血清阳性率均超过 95%。除 15-19 岁（91.7%）和杜尚别（90.0%）外，所有年龄组和地区的 PV3 血清阳性率均<90%。1-4 岁（82.7%）和 5-9 岁（84.4%）年龄组的 PV3 血清阳性率最低，尤其是库尔干-帖木儿（76.3%）和 RRS（80.0%）地区的 1-4 岁年龄组。仅通过常规服务（年龄为 1-7 岁）免疫的出生队列的 PV3 血清阳性率低于 1995-2002 年期间针对 SIAs 的目标出生队列（8-19 岁）：82.5%比 89.3%，p<0.001。
广泛年龄范围内的 PV3 血清阳性率不理想（<90%），这表明暴发是由于长时间内覆盖率不理想导致易感人群积累所致，特别是在仅通过常规服务免疫的出生队列和暴发开始的地区（库尔干-帖木儿和 RRS）。高 PV1 血清阳性率表明，扩大目标年龄（≤15 岁）的 mOPV1 SIAs 成功地缩小了免疫差距，目前 WPV1 传播的可能性不大。为了加速在长期无脊髓灰质炎地区的暴发控制，应考虑扩大 SIA 目标年龄。
