背景:在2018年至2022年之间,尼日利亚经历了循环疫苗衍生的2型脊髓灰质炎病毒(cVDPV2)的连续传播,共检测到526例cVDPV2型脊髓灰质炎病例,在疫情应对活动中提供了约1.8亿剂单价2型口服脊髓灰质炎病毒疫苗(mOPV2)和4.5亿剂新型2型口服脊髓灰质炎病毒疫苗(nOPV2)。灭活脊髓灰质炎病毒疫苗(IPV)于2015年被引入常规免疫,2021年增加了第二剂。我们旨在评估nOPV2对cVDPV2麻痹的有效性,并将nOPV2的有效性与mOPV2和IPV的有效性进行比较。
方法:在这项回顾性病例对照研究中,我们使用了尼日利亚2017年1月1日至2022年12月31日的急性弛缓性麻痹(AFP)监测数据,使用年龄匹配的,发病匹配,和位置匹配的cVDPV2阴性AFP病例作为测试阴性对照。我们还从3月份开始做了一项平行的前瞻性研究,2021年,使用与案例相同的解决方案中的年龄匹配社区控制。我们包括五月以后出生的孩子,2016年,小于60个月,报告了脊髓灰质炎免疫史(来自运动和IPV的OPV剂量)。我们使用条件性逻辑回归估计了nOPV2对cVDPV2麻痹的每剂量有效性,并将nOPV2的有效性与mOPV2和IPV的有效性进行了比较。
结果:在回顾性病例对照研究中,我们在2017年1月1日至2022年12月31日期间,在尼日利亚确定了509例cVDPV2脊髓灰质炎病例,并进行了病例验证和瘫痪发作.其中,82名儿童因不符合纳入标准而被排除在外,427例合格病例中的363例(85%)与1303例测试阴性对照相匹配.病例报告的OPV和IPV剂量少于测试阴性对照(病例中OPV剂量的平均数量为5·9[SD4·2],对照组为6·7[4·3];363例病例中的95例[26%]比1303例对照中的[39%]报告的一个或多个IPV剂量)。我们发现nOPV2的每剂量有效性较低(12%,95%CI-2至25)和mOPV2(17%,3至29),但两种疫苗之间没有显着差异(p=0·67)。一次IPV剂量的估计有效性为43%(23至58)。在前瞻性研究中,392例合格病例中的181例(46%)与1557例社区对照匹配。使用社区控件,我们发现IPV的有效性很高(89%,95%CI83至93,一次剂量),nOPV2的低每剂量有效性(-23%,-45到-5)和mOPV2(1%,-23至20),nOPV2和mOPV2的每剂量有效性之间没有显着差异(p=0·12)。
结论:我们发现两种口服疫苗的估计有效性没有显着差异,支持在cVDPV2暴发响应中应首选基因更稳定的nOPV2的建议。我们的发现强调了IPV的作用和加强常规免疫的必要性,IPV交付的主要途径。
背景:比尔和梅琳达·盖茨基金会和英国医学研究委员会。
BACKGROUND: Between 2018 and 2022, Nigeria experienced continuous transmission of circulating vaccine-derived type 2
poliovirus (cVDPV2), with 526 cases of cVDPV2 poliomyelitis detected in total and approximately 180 million doses of monovalent type 2 oral poliovirus vaccine (mOPV2) and 450 million doses of novel type 2 oral
poliovirus vaccine (nOPV2) delivered in outbreak response campaigns. Inactivated
poliovirus vaccine (IPV) was introduced into routine immunisation in 2015, with a second dose added in 2021. We aimed to estimate the effectiveness of nOPV2 against cVDPV2 paralysis and compare nOPV2 effectiveness with that of mOPV2 and IPV.
METHODS: In this retrospective case-control study, we used acute flaccid paralysis (AFP) surveillance data in Nigeria from Jan 1, 2017, to Dec 31, 2022, using age-matched, onset-matched, and location-matched cVDPV2-negative AFP cases as test-negative controls. We also did a parallel prospective
study from March, 2021, using age-matched community controls from the same settlement as the cases. We included children born after May, 2016, younger than 60 months, for whom polio immunisation history (doses of OPV from campaigns and IPV) was reported. We estimated the per-dose effectiveness of nOPV2 against cVDPV2 paralysis using conditional logistic regression and compared nOPV2 effectiveness with that of mOPV2 and IPV.
RESULTS: In the retrospective case-control study, we identified 509 cVDPV2 poliomyelitis cases in Nigeria with case verification and paralysis onset between Jan 1, 2017, and Dec 31, 2022. Of these, 82 children were excluded for not meeting inclusion criteria, and 363 (85%) of 427 eligible cases were matched to 1303 test-negative controls. Cases reported fewer OPV and IPV doses than test-negative controls (mean number of OPV doses 5·9 [SD 4·2] in cases vs 6·7 [4·3] in controls; one or more IPV doses reported in 95 [26%] of 363 cases vs 513 [39%] of 1303 controls). We found low per-dose effectiveness of nOPV2 (12%, 95% CI -2 to 25) and mOPV2 (17%, 3 to 29), but no significant difference between the two vaccines (p=0·67). The estimated effectiveness of one IPV dose was 43% (23 to 58). In the prospective
study, 181 (46%) of 392 eligible cases were matched to 1557 community controls. Using community controls, we found a high effectiveness of IPV (89%, 95% CI 83 to 93, for one dose), a low per-dose effectiveness of nOPV2 (-23%, -45 to -5) and mOPV2 (1%, -23 to 20), and no significant difference between the per-dose effectiveness of nOPV2 and mOPV2 (p=0·12).
CONCLUSIONS: We found no significant difference in estimated effectiveness of the two oral vaccines, supporting the recommendation that the more genetically stable nOPV2 should be preferred in cVDPV2 outbreak response. Our findings highlight the role of IPV and the necessity of strengthening routine immunisation, the primary route through which IPV is delivered.
BACKGROUND: Bill & Melinda Gates Foundation and UK Medical Research Council.