脊髓灰质炎疫苗2种序贯免疫程序不同免疫剂次免疫效果的评估

目的评估脊髓灰质炎疫苗2种序贯程序下不同剂次的免疫效果,为新免疫策略和免疫程序制定提供依据。方法 2016—2017年随机抽取天津市适龄接种脊髓灰质炎疫苗的新生儿128人,分A、B、C 3组,A组42人,B组44人,C组42人。A、B 2组接种1剂脊髓灰质炎灭活疫苗(IPV)和2剂脊髓灰质炎减毒活疫苗(OPV)(I-O-O),C组接种3剂IPV(I-I-I)。各组研究对象分别于接种疫苗后不同时间点采血,采用微量中和试验进行抗体检测,并对抗体阳性率和抗体几何平均滴度水平(GMT)进行分析。结果接种1剂次IPV后,A组Ⅰ型、Ⅱ型、Ⅲ型脊髓灰质炎抗体阳转率分别为69.05%(29人)、71.43%(30人)、71.43%(30人)(P0.05),抗体阳性率分别为97.62%(41人)、95.24%(40人)、80.95%(34人),3型脊髓灰质炎抗体GMT间差异无统计学意义(P0.05);接种OPV2或IPV2后,除B组Ⅲ型阳性率为97.73%(43人)外,B组Ⅰ型、Ⅱ型及C组各型阳性率均达到100%,仅Ⅱ型脊髓灰质炎抗体GMT在B、C组间(B组357.42,C组172.28)差异有统计学意义(P0.05);按I-O-O完成全程接种后,A组各型脊髓灰质炎抗体阳性率均为100%,3型脊髓灰质炎抗体GMT分别为1 075.05、464.67、786.53(P0.05)。结论接种1剂次IPV或接种IPV1+OPV2后各型脊髓灰质炎抗体阳性率未全部达到100%,接种2剂次IPV后各型脊髓灰质炎抗体阳性率均可达到100%;I-O-O序贯程序可以诱导研究对象产生保护性抗体,但在降低脊髓灰质炎的发生可能性方面,I-I-O序贯程序优于I-O-O。     

脊髓灰质炎灭活疫苗与二价脊髓灰质炎减毒活疫苗两种序贯基础免疫程序的免疫原性比较

目的比较脊髓灰质炎(脊灰)灭活疫苗(Inactivated poliovirus vaccine,IPV)与I+III型二价脊灰减毒活疫苗(Bivalent oral poliovirus vaccine,b OPV)两种序贯基础免疫程序的免疫原性。方法在河北省肥乡区招募健康婴儿,随机分成两组,按2-3-4月龄基础免疫程序分别接种IPV-b OPV-b OPV和IPV-IPV-b OPV,检测基础免疫前和免疫后28-42d血清脊灰病毒Ⅰ、Ⅱ、Ⅲ型中和抗体,分析中和抗体阳性率、阳转率和几何平均滴度(Geometric mean titer,GMT)。结果 IPV-b OPV-b OPV、IPV-IPV-b OPV程序组分别招募受试者69名、68名,两组婴儿基础免疫后脊灰病毒中和抗体阳性率分别为Ⅰ型100%、100%,Ⅱ型98.55%、100%,Ⅲ型100%、100%;阳转率分别为Ⅰ型100%、100%,Ⅱ型97.06%、100%(Fisher确切概率法,P0.05),Ⅲ型100%、100%;GMT增长倍数分别为Ⅰ型758倍、810倍(Z=-0.62,P=0.535),Ⅱ型5倍、26倍(Z=-5.15,P0.001),Ⅲ型379倍、634倍(Z=-3.34,P=0.001)。结论两种IPV与b OPV序贯基础免疫程序均具有良好的免疫原性;IPV-IPV-b OPV程序对Ⅱ、Ⅲ型脊灰病毒的免疫原性优于IPV-b OPV-b OPV程序。     

脊灰疫苗转换后不同疫苗组合免疫效果和成功率分析

目的分析单剂次IPV和两剂次IPV+bOPV两种不同序贯程序的脊灰基础免疫效果。方法在免疫前及应用1IPV+2bOPV和2IPV+1bOPV两种模式完成脊灰基础免疫后1个月,进行调查和采集静脉血,用微量中和试验检测脊灰Ⅰ～Ⅲ型中和抗体水平。结果脊灰Ⅰ、Ⅱ、Ⅲ型中和抗体阳性率免疫前分别为71.9%、56.1%、42.1%;用两种免疫模式完成基础免疫后,Ⅰ型和Ⅲ型脊灰中和抗体阳性率和免疫成功率均达到92%以上,几何平均滴度(GMT)值均1∶800;单剂次和两剂次IPV接种模式免疫后,Ⅱ型脊灰中和抗体阳性率分别为80.7%和96.2%,免疫成功率分别为51.6%和73.1%,GMT值分别为1∶9.15和1∶33.75,说明两剂次IPV免疫后GMT值显著高于单剂免疫。结论两种免疫模式均能确保脊灰I和Ⅲ型中和抗体维持高阳性率和高抗体水平,两剂次IPV免疫模式能更好地提高Ⅱ型脊灰中和抗体的免疫成功率并达到较高的GMT值水平。     

7岁以下儿童接种1剂次或2剂次Salk-IPV免疫效果的Meta分析

目的评价7岁以下儿童接种1剂次或2剂次Salk株脊髓灰质炎灭活疫苗(Salk-IPV)的免疫效果,为实施灭活脊髓灰质炎疫苗(IPV)序贯免疫时制定相应的免疫程序提供参考。方法通过检索美国国家医学图书馆数据库(NCBI)、Cochrane协作网图书馆、中国生物医学文献数据库(CBMdisc)、知网数据库(CNKI)和万方数据库,将评价Salk-IPV免疫效果的研究纳入分析。以7岁儿童接种疫苗至少1个月后诱导中和抗体的血清阳转率(SR)作为观察指标进行Meta分析;描述接种不同剂次Salk-IPV接种后血清型脊髓灰质炎中和抗体的SR的变化趋势。结果共纳入11篇文献,Meta分析结果显示:接种1剂次Salk-IPV后,I、Ⅱ和Ⅲ型脊髓灰质炎病毒中和抗体的SR分别为29%(95%CI:19%~39%)、41%(95%CI:31%~51%)和38%(95%CI:28%~48%);接种2剂次Salk-IPV后,I、Ⅱ和Ⅲ型脊髓灰质炎病毒中和抗体的SR分别为82%(95%CI:74%~90%)、83%(95%CI:77%~88%)和91%(95%CI:87%~95%)。随着免疫起始月龄推后,无论接种1剂次还是2剂次Salk-IPV,不同血清型脊髓灰质炎病毒中和抗体的SR均呈上升趋势。结论 7岁以下儿童采用二价口服脊髓灰质炎减毒活疫苗和Salk-IPV序贯免疫策略时,建议在常规免疫中至少接种2剂次以上Salk-IPV疫苗,血清中和抗体才有较高的阳性率。     

脊髓灰质炎灭活疫苗基础免疫效果观察

目的 考察灭活脊髓灰质炎疫苗(inactivated poliomyelitis vaccine,IPV)在中国婴儿中的免疫效果,并与目前常规使用的口服脊髓灰质炎减毒活疫苗(oral poliomyelitis vaccine,OPV)进行比较.方法 对2个月龄婴儿采用组群随机法分为2个组,每组208名,分别接种IPV和OPV,并采集免疫前后血清.采用微量中和方法,对血清中抗脊髓灰质炎病毒3个型的中和抗体进行测定,对于抗体保护率比较采用X2检验进行统计学处理.抗体滴度进行对数转换后采用Z检验进行比较,所有统计学检验以P<0.05来确定差异是否具有统计学意义.结果婴儿经初次免疫后,IPV组Ⅰ、Ⅱ、Ⅲ型病毒中和抗体保护率分别为100.0%(186/186)、97.3%(181/186)、98.9%(184/186),几何平均滴度(GMT)分别为151.2、86.7、211.3,OPV组Ⅰ、Ⅱ、Ⅲ型病毒中和抗体保护率分别为97.4%(188/193)、100.0%(193/193)、95.3%(184/193),GMT分别为1089.5、538.2、203.7.两组中Ⅰ、Ⅱ型的保护率差异没有统计学意义(Ⅰ、Ⅱ型分别为X2Ⅰ=2.991,P=0.084;X2Ⅱ=3.512,P=0.061),但Ⅲ型中差异有统计学意义(X2Ⅱ=4.143,P=0.042).IPV组Ⅰ、Ⅱ型抗体几何平均滴度低于OPV疫苗,差异有统计学意义(ZⅠ=12.537,P=0.000;ZⅡ=13.415,P=0.000),而Ⅲ型抗体几何平均滴度差异没有统计学意义(ZⅢ=0.067,P=0.947).结论 经基础免疫后IPV在婴儿中免疫效果良好,和OPV相比,IPV组Ⅰ、Ⅱ型保护率与OPV相当,Ⅲ型高于OPV组.IPV组Ⅰ、Ⅱ型抗体几何平均滴度低于OPV疫苗,而Ⅲ型抗体几何平均滴度与OPV组相当.     

北京市二价脊髓灰质炎减毒活疫苗引入前后不同基础免疫程序效果和疫苗效价分析

目的了解二价脊髓灰质炎(脊灰)减毒活疫苗(b OPV)引入前后北京市2014年和2016年不同基础免疫程序免疫效果和疫苗效价。方法 2014年和2016年脊灰疫苗基础免疫程序分别为3剂三价脊灰减毒活疫苗(t OPV)全程免疫和1剂脊灰灭活疫苗(IPV)与2剂二价脊灰减毒活疫苗(b OPV)序贯免疫,分别在北京市两个区选择完成基础免疫后4-8周的婴儿,采集血标本以检测脊灰病毒中和抗体,同时采集不同疫苗储运环节的疫苗标本以检测疫苗效价。结果 2014年和2016年分别调查儿童72人和68人。2014年基础免疫后Ⅰ、Ⅲ型脊灰病毒中和抗体阳性率分别为98.61%和100%,抗体滴度(1∶)[中位数(四分位数间距)]分别为1 536(1 024-1 536)、1 536(512-1 536);2016年基础免疫后Ⅰ型、Ⅲ型脊灰病毒中和抗体阳性率均为100%,抗体滴度(1∶)分别为1 024(512-1 536)、1 536(1 024-1 536)。2014年和2016年Ⅰ、Ⅲ型脊灰病毒中和抗体分布均有显著性差异(Ⅰ型:χ2=8.77,P=0.038;Ⅲ型:χ2=16.76,P=0.001)。2014年t OPV的平均效价为6.1±0.1Lg CCID50/剂,2016年b OPV的平均效价为6.9±0.2Lg CCID50/剂(t=-7.76,P0.001)。结论新疫苗b OPV引入后,IPV-b OPV序贯免疫程序的基础免疫效果与引入前的t OPV全程和IPV-t OPV序贯免疫程序效果一样好;疫苗储运各环节疫苗效价均合格,冷链运转良好。     

肾综合征出血热疫苗交叉加强免疫抗体应答水平

目的：研究在肾综合征出血热（HFRS）双价灭活疫苗基础免疫的基础上，1年后分别用双价苗和Ⅰ型、Ⅱ型单价苗分别进行加强免疫，以观察不同型别疫苗加强后机体的抗体应答水平及区别，以确定加强疫苗剂型。方法：对206名疫苗接种中的部分接种，在基础免疫后2周及1年后（加强前）和加强后2周、1年分别采集血清，以间接免疫荧光试验（IFA）和微量细胞病变中和试验（MCPENT）检测IFA-IgG抗体和中和抗体。结果：（1）基础免疫后2周IFA-IgG抗体阳转率为96.76％，GMT为38.05；中和抗体阳转率：Ⅰ型为100％，Ⅱ型为92.50％；中和抗体GMT：Ⅰ型为20.82，Ⅱ型为15.66。（2）基础免疫后1年（加强前）IFA-IgG抗体阳转率降为51.91％，GMT也降到25.45；中和抗体阳转率：Ⅰ型为55.81％，Ⅱ型为46.51％。中和抗体GMT也分别降到5.45和5.18。（3）加强免疫后2周IFA-IgG抗体阳转率回升到98.46％，GMT也上升到38.02；同时中和抗体率：3组两型抗体均为100％阳转；Ⅰ型抗体GMT分别为20.01，46.66和12.42；Ⅱ型抗体和GMT分别为20.00、19.99和16.82。结论：在双价疫苗基础免疫的基础上，通过3种疫苗加强免疫，产生的IFA抗体和中和抗体在阳性率和GMT水平3组间很接近，但Ⅰ型苗组应答的Ⅰ型中和抗体GMT是3组中最高的。提示：在双价苗基础免疫的基础上，可以考虑使用与该疫区相同型别的单价疫苗进行加强免疫，以降低疫苗接种成本和减轻接种的经济负担。     

产妇与婴儿脊髓灰质炎中和抗体水平变化特征分析

目的评价脊髓灰质炎中和抗体在产妇及其婴儿体内消长规律,比较不同免疫程序下婴儿抗体水平变化。方法选取2013年7月—2014年4月在广州市荔湾区妇幼保健院进行分娩的产妇及其新生儿作为研究对象,采用血清流行病学方法对产妇及产妇所生婴儿0(新生儿)、3、6月龄脊灰中和抗体水平进行分析;并根据婴儿基础免疫程序将其分为脊髓灰质炎减毒活疫苗(OPV)组、脊髓灰质炎灭活疫苗(IPV)与IPV+OPV 3组,比较疫苗接种后的抗体水平。结果共采集179位产妇外周静脉血,婴儿0、3、6月龄时分别采血176、149、62份。新生儿较产妇I、II、III型脊灰中和抗体水平有所下降,3、6月龄时抗体水平均大幅上升,6月龄时各型分别高达607.0(95%CI=146.0~2 523.1)、239.6(95%CI=80.4~713.6)和235.9(95%CI=56.0~994.8)。OPV、IPV、IPV+OPV组在婴儿各个时间段脊灰I、II、III型抗体几何平均滴度倒数(GMRT)和抗体阳性率差异均无统计学意义(均P0.05)。产妇脊灰抗体水平与新生儿脊灰Ⅱ、III型母传抗体呈显著正相关关系(tII=5.953、P=0.000,tIII=7.260、P0.001)。结论新生儿脊灰胎传抗体水平较母体下降。IPV全程接种、IPV与OPV序贯免疫对婴儿均有较好的免疫原性,中国现阶段可大力推进IPV与OPV序贯免疫程序。     

首剂脊髓灰质炎灭活疫苗纳入儿童基础免疫程序效果评价

目的评价首剂脊髓灰质炎(脊灰)灭活疫苗(IPV)与二价口服脊灰减毒活疫苗(bOPV)序贯基础免疫程序的效果。方法采用分层随机抽样方法选取重庆市脊灰基础免疫适龄儿童,分为实验1组(SG1)、实验2组(SG2)、对照组(CG),分别按Salk株IPV(IPVSalk)-bOPV-bOPV、Sabin株IPV(IPVSabin)-bOPV-bOPV、三价口服脊灰减毒活疫苗(tOPV)-bOPV-bOPV序贯程序完成3剂脊灰疫苗基础免疫,其中SG1和SG2组IPV从2018年8月1日开始接种,CG组tOPV于2016年4月1-30日接种,在基础免疫完成后1-3个月检测儿童血清脊灰中和抗体。结果 SG1、SG2、CG组分别纳入儿童335名、358名、334名。完成脊灰疫苗基础免疫后,各组I型脊灰抗体保护率分别为99.70%、99.70%、98.50%(Fisher精确概率法,SG1与CG:P=0.12;SG2与CG:P=0.11;SG1与SG2:P=1.00),II型分别为83.28%、74.58%、98.80%(χ2=49.34,P=0.00;χ2=85.59,P=0.00;χ2=7.84,P=0.01),III型分别为99.40%、100%、97.90%(Fisher精确概率法,P=0.11;P=0.01;P=0.23)。结论实验组儿童I型和III型脊灰中和抗体保持较高水平,首剂IPV与bOPV序贯免疫程序效果良好。     

梅州市Sabin株脊髓灰质炎灭活疫苗替代减毒活疫苗序贯程序免疫效果

目的在消灭脊髓灰质炎(脊灰)后期,分析用Sabin株脊灰灭活疫苗(IPV)替代首剂脊灰减毒活疫苗(OPV)的"1剂Sabin株IPV+3剂OPV序贯程序"的有效性、安全性。方法采用描述流行病学方法,对梅州市2008—2017年急性弛缓性麻痹(AFP)病例、2015年12月—2017年11月Sabin株IPV替代首剂OPV免疫后疑似预防接种异常反应(AEFI)病例监测结果进行分析。结果免疫策略调整前8年梅州市发生4例疫苗相关麻痹型脊灰(VAPP),发病率为0.21/10万。Sabin株IPV替代首剂OPV后,可获得较好的脊灰中和抗体保护率,2年未发生VAPP、疫苗衍生脊灰病毒(VDPV)病例。主动、被动监测结果显示,AEFI发生率分别为542.51/10万、65.52/10万,以一般反应为主,异常反应发生率和同期接种的第一、二类疫苗性差异无统计学意义。结论梅州市采用"1剂次Sabin株IPV+3剂次OPV"的序贯免疫程序2年来,保持高水平脊灰免疫屏障,消除脊灰野毒株传入的风险,并且防止了VAPP、VDPV病例的发生。     

Immunogenicity of four doses of oral poliovirus vaccine when co-administered with the human neonatal rotavirus vaccine (RV3-BB)

BackgroundThe RV3-BB human neonatal rotavirus vaccine was developed to provide protection from severe rotavirus disease from birth. The aim of this study was to investigate the potential for mutual interference in the immunogenicity of oral polio vaccine (OPV) and RV3-BB.MethodsA randomized, placebo-controlled trial involving 1649 participants was conducted from January 2013 to July 2016 in Central Java and Yogyakarta, Indonesia. Participants received three doses of oral RV3-BB, with the first dose given at 0–5 days (neonatal schedule) or ~8 weeks (infant schedule), or placebo. Two sub-studies assessed the immunogenicity of RV3-BB when co-administered with either trivalent OPV (OPV group, n = 282) or inactivated polio vaccine (IPV group, n = 333). Serum samples were tested for antibodies to poliovirus strains 1, 2 and 3 by neutralization assays following doses 1 and 4 of OPV.ResultsSero-protective rates to poliovirus type 1, 2 or 3 were similar (range 0.96–1.00) after four doses of OPV co-administered with RV3-BB compared with placebo. Serum IgA responses to RV3-BB were similar when co-administered with either OPV or IPV (difference in proportions OPV vs IPV: sIgA responses; neonatal schedule 0.01, 95% CI −0.12 to 0.14; p = 0.847; infant schedule −0.10, 95% CI −0.21 to −0.001; p = 0.046: sIgA GMT ratio: neonatal schedule 1.23, 95% CI 0.71–2.14, p = 0.463 or infant schedule 1.20, 95% CI 0.74–1.96, p = 0.448).ConclusionsThe co-administration of OPV with RV3-BB rotavirus vaccine in a birth dose strategy did not reduce the immunogenicity of either vaccine. These findings support the use of a neonatal RV3-BB vaccine where either OPV or IPV is used in the routine vaccination schedule.     

Serological response and poliovirus excretion following different combined oral and inactivated poliovirus vaccines immunization schedules

A controlled study was conducted in Karachi, Pakistan to compare humoral and mucosal immune responses against polioviruses in infants who received oral poliovirus vaccine (OPV) at birth and at 6, 10, and 14 weeks according to the Expanded Program on Immunization (EPI) with infants who received either three doses of inactivated poliovirus vaccine (IPV) at 6, 10, and 14 weeks together with OPV or one additional dose of IPV at 14 weeks together, with the last dose of OPV. A total of 1429 infants were enrolled; 24-week serum specimens were available for 898 infants (63%). They all received a challenge dose of OPV type 3 at 24 weeks of age. The addition of three doses of IPV to three doses of OPV induced a significantly higher percentage of seropositive children at 24 weeks of age for polio 1 (97% versus 89%, P<0.001) and polio 3 (98% versus 92%) compared to the EPI schedule. However, the one supplemental dose of IPV at 14 weeks did not increase the serological response at 24 weeks. Intestinal immunity against the challenge dose was similar in the three groups. Combined schedules of OPV and IPV in the form of diphtheria-pertussis-tetanus-IPV vaccine (DPT-IPV) may be useful to accelerate eradication of polio in developing countries.     

Immunogenicity and reactogenicity of rhesus rotavirus vaccine given in combination with oral or inactivated poliovirus vaccines and diphtheria-tetanus-pertussis vaccine.

Immunogenicity and reactogenicity of the oral rhesus rotavirus vaccine (RRV) were assessed among 72 infants (6 weeks old) in Lahore, Pakistan, from August to December 1985. Special emphasis was placed on the possible interaction or interference caused by giving RRV at the time infants received their first polio immunization. RRV was given to the infants at the same time as diphtheria-tetanus-pertussis (DTP), oral poliovirus vaccine (OPV), or inactivated poliovirus vaccine (IPV). The immune response to RRV was assessed by plaque-reduction neutralization 3 weeks after immunization and serum immunoglobulin (Ig) G and IgA antibody levels to poliovirus type 1 were tested by enzyme-linked immunosorbent assay (ELISA) after polio immunizations. Of the infants in the group given RRV with OPV, 50% had a two- to four-fold rise in neutralization titre against rotavirus, compared with 22% in the group given RRV with DTP and 20% in the group given RRV and IPV (P less than 0.05). Interference by live oral polio vaccination in the response to RRV seems unlikely. We observed no significant difference in rates of seroconversion of IgG antibodies to poliovirus type 1 among infants aged 18 and 21 weeks who received RRV and OPV (81%), RRV with delayed OPV (67%), or RRV and IPV (59%). Administration of RRV was safe and was not associated with adverse reactions in the 6 weeks old infants. The low rate of seroconversion to rotavirus suggests that a more antigen-rich vaccine or multiple doses of the same vaccine might produce a better immune response.     

A mucosal adjuvant for the inactivated poliovirus vaccine

The eradication of poliovirus from the majority of the world has been achieved through the use of two vaccines: the inactivated poliovirus vaccine (IPV) and the live-attenuated oral poliovirus vaccine (OPV). Both vaccines are effective at preventing paralytic poliomyelitis, however, they also have significant differences. Most importantly for this work is the risk of revertant virus from OPV, the greater cost of IPV, and the low mucosal immunity induced by IPV. We and others have previously described the use of an alphavirus-based adjuvant that can induce a mucosal immune response to a co-administered antigen even when delivered at a non-mucosal site. In this report, we describe the use of an alphavirus-based adjuvant (GVI3000) with IPV. The IPV-GVI3000 vaccine significantly increased systemic IgG, mucosal IgG and mucosal IgA antibody responses to all three poliovirus serotypes in mice even when administered intramuscularly. Furthermore, GVI3000 significantly increased the potency of IPV in rat potency tests as measured by poliovirus neutralizing antibodies in serum. Thus, an IPV-GVI3000 vaccine would reduce the dose of IPV needed and provide significantly improved mucosal immunity. This vaccine could be an effective tool to use in the poliovirus eradication campaign without risking the re-introduction of revertant poliovirus derived from OPV.     

Polio vaccination coverage and seroprevalence of poliovirus antibodies after the introduction of inactivated poliovirus vaccines for routine immunization in Japan

In Japan, the oral poliovirus vaccine (OPV) was changed to 2 types of inactivated poliovirus vaccine (IPV), the standalone conventional IPV (cIPV) and the Sabin-derived IPV combined with diphtheria-tetanus-acellular pertussis vaccine (DTaP-sIPV), for routine immunization in 2012. We evaluated polio vaccination coverage and the seroprevalence of poliovirus antibodies using data from the National Epidemiological Surveillance of Vaccine-Preventable Diseases (NESVPD) from 2011 to 2015. Several years before the introduction of IPV in 2012, OPV administration for children was refused by some parents because of concerns about the risk of vaccine-associated paralytic poliomyelitis. Consequently, in children aged <1?years who were surveyed in 2011–2012, polio vaccination coverage (45.0–48.8%) and seropositivity rates for poliovirus (type 1: 51.7–65.9%, type 2: 48.3–53.7%, and type 3: 15.0–29.3%) were decreased compared to those surveyed in 2009. However, after IPV introduction, the vaccination coverage (95.5–100%) and seropositivity rates (type 1: 93.2–96.6%, type 2: 93.1–100%, and type 3: 88.6–93.9%) increased among children aged <1?years in 2013–2015. In particular, seropositivity rates and geometric mean titers (GMTs) for poliovirus type 3 in <5-year-old children who received 4 doses of IPV (98.5% and 247.4, respectively) were significantly higher than in those who received 2 doses of OPV (72.5% and 22.9, respectively). Furthermore, in <5-year-old children who received 4 doses of either DTaP-sIPV or cIPV, the seropositivity rates and the GMTs for all 3 types of poliovirus were similarly high (96.5–100% and 170.3–368.8, respectively). Our findings from the NESVPD demonstrate that both the vaccination coverage and seropositivity rates for polio remained high in children after IPV introduction.     

PER.C6 cells as a serum-free suspension cell platform for the production of high titer poliovirus: A potential low cost of goods option for world supply of inactivated poliovirus vaccine

There are two highly efficacious poliovirus vaccines: Sabin's live-attenuated oral polio vaccine (OPV) and Salk's inactivated polio vaccine (IPV). OPV can be made at low costs per dose and is easily administrated. However, the major drawback is the frequent reversion of the OPV vaccine strains to virulent poliovirus strains which can result in Vaccine Associated Paralytic Poliomyelitis (VAPP) in vaccinees. Furthermore, some OPV revertants with high transmissibility can circulate in the population as circulating Vaccine Derived Polioviruses (cVDPVs). IPV does not convey VAPP and cVDPVs but the high costs per dose and insufficient supply have rendered IPV an unfavorable option for low and middle-income countries.     

Immunogenicity to poliovirus type 2 following two doses of fractional intradermal inactivated poliovirus vaccine: A novel dose sparing immunization schedule

IntroductionThe polio eradication endgame strategic plan calls for the sequential removal of Sabin poliovirus serotypes from the trivalent oral poliovirus vaccine (tOPV), starting with type 2, and the introduction of ≥1 dose of inactivated poliovirus vaccine (IPV), to maintain an immunity base against poliovirus type 2. The global removal of oral poliovirus type 2 was successfully implemented in May 2016. However, IPV supply constraints has prevented introduction in 21 countries and led to complete stock-out in >20 countries.MethodsWe conducted a literature review and contacted corresponding authors of recent studies with fractional-dose IPV (fIPV), one-fifth of intramuscular dose administered intradermally, to conduct additional type 2 immunogenicity analyses of two fIPV doses compared with one full-dose IPV.ResultsFour studies were identified that assessed immunogenicity of two fIPV doses compared to one full-dose IPV. Two fractional doses are more immunogenic than 1 full-dose, with type 2 seroconversion rates improving between absolute 19–42% (median: 37%, p < 0.001) and relative increase of 53–125% (median: 82%), and antibody titer to type 2 increasing by 2–32-fold (median: 10-fold). Early age of administration and shorter intervals between doses were associated with lower immunogenicity.DiscussionOverall, two fIPV doses are more immunogenic than a single full-dose, associated with significantly increased seroconversion rates and antibody titers. Two fIPV doses together use two-fifth of the vaccine compared to one full-dose IPV. In response to the current IPV shortage, a schedule of two fIPV doses at ages 6 and 14 weeks has been endorsed by technical oversight committees and has been introduced in some affected countries.     

The novel adjuvant dmLT promotes dose sparing,mucosal immunity and longevity of antibody responses to the inactivated polio vaccine in a murine model

One option for achieving global polio eradication is to replace the oral poliovirus vaccine (OPV), which has the risk of reversion to wild-type virulence, with the inactivated poliovirus vaccine (IPV) vaccine. Adjuvants and alternate routes of immunization are promising options that may reduce antigen dose in IPV vaccinations, potentially allowing dose sparing and cost savings. Use of adjuvants and alternate routes of immunization could also help promote mucosal immunity, potentially mimicking the protection against intestinal virus shedding seen with OPV. In the current study, we examined the impact of combining the novel adjuvant dmLT with trivalent IPV for dose sparing, induction of mucosal immunity and increasing longevity of anti-poliovirus (PV) responses in a mouse model following either intradermal (ID) or intramuscular (IM) delivery.We found that non-adjuvanted ID delivery was not superior to IM delivery for fractional dose sparing, but was associated with development of mucosal immunity. Vaccination with IPV + dmLT promoted serum anti-PV neutralizing antibodies with fractional IPV doses by either IM or ID delivery, achieving at least five-fold dose sparing above non-adjuvanted fractional doses. These responses were most noticeable with the PV1 component of the trivalent vaccine. dmLT also promoted germinal center formation and longevity of serum anti-PV neutralizing titers. Lastly, dmLT enhanced mucosal immunity, as defined by fecal and intestinal anti-PV IgA secretion, when included in IPV immunization by ID or IM delivery. These studies demonstrate that dmLT is an effective adjuvant for either IM or ID delivery of IPV. Inclusion of dmLT in IPV immunizations allows antigen dose sparing and enhances mucosal immunity and longevity of anti-PV responses.