2012—2018年青州市1～7岁儿童免疫规划疫苗接种率的调查分析

目的对山东省免疫规划信息系统(immunization information system, IIS)中,2012—2018年青州市1～7岁儿童免疫规划疫苗接种率进行分析。方法通过山东省IIS平台,收集青州市1～7岁儿童预防接种信息个案,分年龄、接种门诊和户籍类型,对疫苗接种率进行描述性分析。结果 2012—2018年青州市共收集1～7岁儿童个案77 856例。常住儿童为75 504例,流动儿童为2 352例。各年龄组免疫规划疫苗接种率均在89.42%～100%;BCG接种率最高,达到99.95%～100.00%;MenAC2接种率较低,>6～7岁组接种率为89.42%;MCV3为山东省增加剂次,其接种率相对较低,为90.60%。青州市20个预防接种门诊中,1～6岁儿童应种疫苗接种率均在98.41%～98.58%之间;>4～6岁组应种疫苗接种率最高,接种率为98.58%;>6～7岁组则接种率较低,仅84.03%。何官卫生院应种疫苗接种率最高,各年龄组免疫规划疫苗接种率99.51%～100.00%;云门山卫生院应种疫苗接种率较低,>6～7岁组仅62.61%。流动儿童接种率低于常住儿童。结论青州市免疫规划工作开展较好,6岁以下年龄组儿童免疫规划疫苗接种率处于较高水平;6～7岁组和流动儿童的疫苗接种率相对较低;提高大年龄组疫苗接种率是青州市预防接种管理的重点。     

潍坊市实施儿童预防接种信息化管理系统建设效果评价

目的了解潍坊市儿童预防接种个案信息化管理情况,为免疫规划管理提供科学依据。方法采用《金苗免疫助手系统》软件,建立儿童预防接种个案数据库,通过磁卡识别系统进行接种。结果截至2010年儿童接种个案信息常住与流动儿童分别录入794 015和117 192人,录入管理率分别为99.80%、96.11%;流动儿童建卡、证信息化电子网络管理前后相比具有统计学意义(χ2=4.52,0.01相似文献   

杭州地区婴儿麻疹流行特征与疫苗接种史的相关性分析

本文旨在探讨当前我国麻疹疫苗接种程序下的婴儿麻疹流行特征,为改进麻疹疫苗接种策略提供科学依据。利用麻疹监测系统,对杭州市2004～2007年婴儿麻疹发病的分布和疫苗免疫状况进行分析,发现婴儿麻疹发病率无明显城乡差异,发病季节主要集中在3～5月,发病年龄主要集中在5～9月龄。≤8月龄病例以常住儿童为主,≥9月龄病例以流动儿童为主。≥9月龄麻疹病例中,常住儿童所占比例低于流动儿童,而其麻疹疫苗接种率(47.5%)明显高于流动儿童(14.3%),两者有显著差异(χ2=11.75,P0.01)。因此,为进一步降低婴儿麻疹发病率,需加强流动儿童的麻疹疫苗补种;另外,建议将麻疹疫苗初次免疫时间提前至6月龄,这可能有助于降低婴儿麻疹发病率。     

鱼山镇1岁以上人群不同年龄组乙肝表面抗原携带率与乙肝疫苗接种关系的调查

研究鱼山镇乙肝疫苗接种率不同人群的乙肝病毒表面抗原(HBsAg)携带率的差异。将该镇所有户籍登记在册人员按出生日期分成3组,再按随机抽样法对每个年龄组抽取一定数量的人组成样本,调查乙肝疫苗接种史;对每位参加者采集静脉血5ml,无菌分离血清,使用固相放射免疫试剂和酶联免疫试剂检测乙肝病毒表面抗原和抗乙肝病毒表面抗原抗体(HBsAb,抗-HBs)。小年龄组、中年龄组、大年龄组乙肝疫苗接种率依次为80.00%、50.46%、25.36%,差异具有统计学意义(χ2=262.24,P<0.005);小年龄组、中年龄组、大年龄组HBsAg携带率依次为2.07%、11.93%、17.87%,差异具有统计学意义(χ2=77.48,P<0.005);小年龄组、中年龄组、大年龄组HBsAb依次为43.38%、24.77%、10.95%,差异具有统计学意义(χ2=107.28,P<0.005)。乙肝疫苗接种率在小年龄组、中年龄组、大年龄组依次降低,HBsAg携带率依次增高,HBsAb阳性率依次降低。因此,接种乙肝疫苗对人群有较好的保护作用,人群乙肝疫苗接种率越高,HBsAb阳性率越高,HBsAg携带率越低。     

婴儿脊灰母传抗体对Sabin株脊髓灰质炎灭活疫苗不同序贯免疫接种程序效果的影响

目的探讨婴儿脊髓灰质炎(简称脊灰)母传抗体对Sabin株脊髓灰质炎灭活疫苗(Sabin inactivated poliovirus vaccine,s IPV)与不同剂型脊髓灰质炎减毒活疫苗(oral poliovirus vaccine,OPV)采用不同序贯免疫程序接种效果的影响。方法选取柳州市600名2月龄无脊髓灰质炎疫苗免疫史的常住健康婴儿,分为6个序贯免疫组,其中1剂s IPV+2剂b OPV 2组:s IPV+2b OPV(糖丸)组、s IPV+2b OPV(液体)组;2剂s IPV+1剂b OPV 2组:2s IPV+b OPV(糖丸)组、2s IPV+b OPV(液体)组;2剂s IPV+1剂t OPV 2组:2s IPV+t OPV(糖丸)组,2s IPV+t OPV(液体)组。每组100人。按照0、28、56 d程序,分别在婴儿2、3、4月龄时接种相应疫苗。检测免前、全程免后28 d血清中脊灰中和抗体滴度,计算阳转率及GMT。结果 6个序贯免疫组免前各项指标分布均匀,各型脊灰抗体阳性率、抗体水平及分布均无明显差异。共有518例免前和免后配对血清抗体检测结果的研究对象进入免疫原性分析。s IPV+2b OPV组与2s IPV+b OPV组Ⅱ型抗体、2s IPV+t OPV(糖丸)组Ⅲ型抗体免前阴性和免前阳性者接种疫苗后阳转率差异均有统计学意义;s IPV+2b OPV(糖丸)组Ⅲ型抗体,2s IPV+b OPV(糖丸)组与2s IPV+b OPV(液体)组Ⅱ型抗体,2s IPV+t OPV(糖丸)组Ⅰ、Ⅱ型抗体的免前阳性与免前阴性者接种疫苗后的GMT差异均有统计学意义;2s IPV+t OPV(糖丸)Ⅰ型抗体组与2s IPV+t OPV(液体)Ⅱ型抗体组中,免前8~32、≥32两种滴度水平的免后GMT差异均有统计学意义。结论脊灰疫苗序贯免疫效果受脊灰母传抗体干扰。     

潍坊市健康人群麻疹、风疹、流行性腮腺炎抗体水平调查

目的了解潍坊市健康人群麻疹、风疹、流行性腮腺炎血清抗体水平,为消除麻疹、控制风疹及腮腺炎疫情提供依据。方法 2011年8月,采集昌乐、潍城2个县区<2、2～5、5～8、8～11、11～15、15～20、20～40、>40岁健康人群血标本,应用酶联免疫吸附试验检测麻疹、风疹、腮腺炎IgG抗体。结果检测总数320人,其中昌乐县健康人群的麻疹抗体阳性率为98.75%、潍城为96.25%;风疹抗体阳性率昌乐县健康人群为89.38%、潍城区为91.88%。昌乐、潍城两地区健康人群麻疹、风疹的抗体阳性率差异均无统计学意义(χ2=1.15、0.59,P>0.05);昌乐县健康人群腮腺炎抗体阳性率为84.38%、潍城区健康人群为66.25%,两者差异有统计学意义(χ2=14.14,P<0.01);8组不同年龄健康人群的麻疹抗体阳性率为92.50%～100%,风疹抗体阳性率为87.50%～92.50%,腮腺炎抗体阳性率为67.50%～85.00%,各年龄组间均无统计学意义(χ2=13.49、1.58、5.23,P>0.05)。结论潍坊市麻疹抗体阳性率较高,风疹、腮腺炎抗体阳性率相对偏低,今后须要积极开展学龄儿童麻腮风三联疫苗的查漏补种工作。     

儿童2剂水痘疫苗不同间隔免疫程序的比较

目的了解水痘疫苗2剂不同间隔时间免疫程序的安全性及免疫原性。方法按照随机、双盲的原则,选择符合条件的1~3岁、4~6岁、7~12岁儿童各200名,每个年龄组按照2剂间隔3个月和6个月的免疫程序,分别接种2剂冻干水痘减毒活疫苗。观察各组接种后的不良反应率,用膜抗原荧光抗体法(FAMA)检测疫苗接种前、后血清抗体阳转率、GMT水平和平均增长倍数。结果接种2剂水痘疫苗后,总体不良反应率在4%~13%;同年龄组不同间隔时间接种2剂疫苗后,不良反应发生率差异无统计学意义;不同年龄组间不良反应发生率差异无统计学意义。同年龄组不同间隔时间免前及接种2剂后,血清GMT水平差异均无统计学意义;同年龄组接种1剂与2剂水痘疫苗的血清GMT水平,两者间差异有显著性统计学意义。接种2剂水痘疫苗的GMT增长倍数高于接种1剂。不同间隔时间接种第2剂水痘疫苗后抗体阳转率差异无统计学意义;同年龄组接种2剂后抗体阳转率高于接种1剂,两者差异有统计学意义。结论间隔3个月和6个月接种第2剂水痘疫苗,在安全性及免后GMT水平、增长倍数及抗体阳转率等4个方面,两者差异均无统计学意义。     

新疆生产建设兵团儿童乙型肝炎疫苗接种率现况分析

目的:了解新疆生产建设兵团1992年以后出生儿童乙型肝炎疫苗接种情况和影响因素,为相关部门决策提供依据.方法:在南疆、北疆的8个年龄层等比例随机抽取儿童918名,进行乙型肝炎疫苗接种率问卷调查.用SPSS13.0软件进行统计学处理.结果:①儿童乙型肝炎疫苗首针及时接种率为65.7%(标准化率79.28%);全程接种率为70.2%(标准化率72.15%).②南疆、北疆儿童首针及时接种率分别为51.O%、82.5%,全程接种率分别为54.9%、87.6%.③在医院内、医院外出生儿童首针及时接种率分别为90.4%、54.1%,全程接种率分别为89.8%、61.0%.④汉族、少数民族儿童首针及时接种率分别为68.2%、60.9%,全程接种率分别为72.1%、66.3%.结论新疆生产建设兵团儿童乙型肝炎疫苗全程接种率低于全国平均水平.乙型肝炎疫苗接种率南疆高于北疆、在医院出生儿童高于在医院外出生儿童.汉族儿童的全程接种率相对较高.     

钦州市2005—2014年麻疹疫苗强化免疫前后麻疹流行病学特征分析

目的分析钦州市麻疹疫苗强化免疫(简称强免)前后麻疹流行病学特征,为消除麻疹提供依据。方法以2009年9月1日为分界点,对2005—2014年麻疹病例按强免前后采用Excel进行数据录入和SPSS19.0进行统计分析。结果强免前后性别分布差异有统计学意义,人群年龄分布总体差异有统计学意义,但8月龄~5岁组差异无统计学意义;职业分布总体差异有统计学意义,但散居儿童组差异无统计学意义;免疫史分布差异无统计学意义。强免前后麻疹高发人群都是以8月龄~5岁组儿童及散居儿童为主。结论根据钦州市麻疹流行特征,提高适龄儿童含麻疹成分疫苗接种率、及时接种率,加强查漏补种,并有计划开展麻疹疫苗强化免疫,这些措施是降低麻疹发病率、最终消除麻疹的关键。     

阳江市健康人群乙型肝炎血清流行病学调查

目的了解阳江市健康人群乙型肝炎表面抗体(抗-HBs)水平,评价乙型肝炎疫苗免疫效果。方法采用整群随机抽样方法,在阳江市辖区内随机抽取20个乡镇的常住健康人群为调查对象。采用电化学发光免疫法定量检测抗-HBs水平,运用SPSS18.0和Excel 2007软件进行数据整理和分析。结果共采集1 054人份血清进行检测,人群中乙肝疫苗接种率为94.88%,抗-HBs阳性率为63.47%、抗-HBs高应答率及GMT分别为29.51%和2 3.47 m IU/m L。乙肝疫苗接种率显示,随着年龄的增长疫苗接种率越低;20岁以下和20岁以上人群疫苗接种率分别为98.35%和54.22%,且男性高于女性;各地区间疫苗接种率差异无统计学意义(χ2=5.99,P=0.11)。抗-HBs阳性率显示,1~14岁儿童抗-HBs阳性率为63.00%。其中,1~岁组儿童最高为87.20%,7~岁组最低为54.56%;江城区抗-HBs阳性率最高(70.61%),阳西县最低(56.60%)。1岁以下儿童的抗-HBs应答率和GMT均最高,分别为61.22%和(91.56±2.15)m IU/m L。5~岁组最低,分别为13.74%和(12.44±1.46)m IU/m L,差异均有显著的统计学意义(χ2=57.31,P=0.00,F=5.77,P=0.00)。结论阳江市健康人群乙肝疫苗接种率高,初步形成免疫屏障。积极开展20岁以下人群的加强免疫和成人的乙肝疫苗的接种工作。     

Role of whole-cell pertussis vaccine in severe local reactions to the preschool (fifth) dose of diphtheria-pertussis-tetanus vaccine.

OBJECTIVE: To estimate the contribution of whole-cell pertussis vaccine to severe local reactions after the preschool (fifth) dose of adsorbed diphtheria toxoid-pertussis vaccine-tetanus toxoid (DPT) vaccine. DESIGN: Double-blind randomized controlled trial. SETTING: Urban community. PARTICIPANTS: Volunteer sample of 200 healthy children 4 to 6 years old who were eligible for the fifth dose of DPT vaccine. INTERVENTIONS: Children received, in both arms, either diphtheria toxoid-tetanus toxoid (DT) and monovalent pertussis vaccines (group A, 99 children) or DPT and meningococcal vaccines (group B, 101 children). All were licensed products from single lots. The children were assessed 24 hours later by a trained observer. Serum samples obtained before vaccination were tested for antibodies to tetanus and diphtheria toxins and five pertussis antigens by means of enzyme-linked immunosorbent assay. MAIN OUTCOME MEASURES: Rates of severe local reactions (an area of redness or swelling or both of 50 mm or greater) 24 hours after vaccination. Relation between serum antibody levels before vaccination and rates of severe local reactions to corresponding vaccines. RESULTS: All of the subjects were followed up 24 hours after vaccination. Severe redness was present in 38% given DPT vaccine, 29% given intramuscular pertussis vaccine and 9% given DT vaccine (p < or = 0.002, three-way comparison). Severe swelling was common after vaccination with all three products. After intramuscular pertussis vaccination a relation was evident between the prevaccination levels of antibody to whole-cell pertussis bacteria and the rates of redness (p < 0.02) but not between the prevaccination subcellular antibody levels and the rates of redness. CONCLUSION: That pertussis vaccine resembled the DPT vaccine in causing severe redness suggests that it is the principal cause of such reactions after DPT vaccination. The DT vaccine was also reactogenic; thus, cumulative sensitization to one or more of its constituents may be a factor.     

Comparative Effectiveness of Different Strategies of Oral Cholera Vaccination in Bangladesh: A Modeling Study

Background

Killed, oral cholera vaccines have proven safe and effective, and several large-scale mass cholera vaccination efforts have demonstrated the feasibility of widespread deployment. This study uses a mathematical model of cholera transmission in Bangladesh to examine the effectiveness of potential vaccination strategies.

Methods & Findings

We developed an age-structured mathematical model of cholera transmission and calibrated it to reproduce the dynamics of cholera in Matlab, Bangladesh. We used the model to predict the effectiveness of different cholera vaccination strategies over a period of 20 years. We explored vaccination programs that targeted one of three increasingly focused age groups (the entire vaccine-eligible population of age one year and older, children of ages 1 to 14 years, or preschoolers of ages 1 to 4 years) and that could occur either as campaigns recurring every five years or as continuous ongoing vaccination efforts. Our modeling results suggest that vaccinating 70% of the population would avert 90% of cholera cases in the first year but that campaign and continuous vaccination strategies differ in effectiveness over 20 years. Maintaining 70% coverage of the population would be sufficient to prevent sustained transmission of endemic cholera in Matlab, while vaccinating periodically every five years is less effective. Selectively vaccinating children 1–14 years old would prevent the most cholera cases per vaccine administered in both campaign and continuous strategies.

Conclusions

We conclude that continuous mass vaccination would be more effective against endemic cholera than periodic campaigns. Vaccinating children averts more cases per dose than vaccinating all age groups, although vaccinating only children is unlikely to control endemic cholera in Bangladesh. Careful consideration must be made before generalizing these results to other regions.     

A comparative evaluation of the immunological efficacy of ADPT vaccine and ADT-M anatoxin in the immunization of children against diphtheria and tetanus

Comparative study of the immunological effectiveness of adsorbed diphtheria-pertussis-tetanus (DPT) vaccine and adsorbed diphtheria-tetanus toxoid with reduced antigen content (adsorbed DT toxoid R) in the immunization of children, carried out in accordance with the vaccination schedule, was made. Immune response to the injection of adsorbed DPT vaccine was higher than after immunization with adsorbed DT toxoid R, as evidenced by antibody titers. It was probably due to differences in the number of injections constituting the course of immunization: it consisted of 3 injections and 1 booster injection for adsorbed DPT vaccine and 2 injections and 1 booster injection for adsorbed DT toxoid R. Immunization with adsorbed DPT vaccine produced immunity which was retained for a longer period. These results are indicative of the expediency of the primary immunization of children with adsorbed DT toxoid R introduced in three injections in order to ensure more stable and prolonged postvaccinal (mainly antidiphtheria) immunity.     

清远市2009—2012年疑似预防接种异常反应监测分析

目的了解广东省清远市疑似预防接种异常反应(AEFI)的发生特征,评价AEFI信息管理系统运转情况及预防接种安全性。方法采用描述流行病学方法对清远市2009—2012年报告的AEFI数据进行统计分析。结果2009—2012年清远市共报告AEFI 553例,年均发生率为7.6/10万,以一般反应为主(72.33%);AEFI监测县区覆盖率、48 h内及时报告率和调查率、个案调查表完整率等运转指标均明显提高;发生时间以3、9、11月份居多(占40.87%),人群以≤2岁婴幼儿为主(占60.58%),接种后1 d内发生AEFI占85.90%;发生率较高的疫苗主要为23价肺炎球菌多糖疫苗、甲型H1N1流感病毒裂解疫苗、b型流感嗜血杆菌结合疫苗、麻疹风疹联合减毒活疫苗、吸附白破联合疫苗、吸附百白破联合疫苗(占46.84%)。结论清远市AEFI集中在小年龄组及接种早期。疫苗的安全性和预防接种服务质量良好。AEFI监测的完整性和敏感性逐年提高。为减少预防接种后不良事件的发生,提高AEFI监测敏感性,须进一步规范预防接种工作,提高预防接种质量,加强AEFI监测。     

Protection of mumps in children with various underlying diseases: application of a live attenuated mumps and trivalent measles-rubella-mumps (MRM) vaccines in these children

A live attenuated mumps and trivalent measles-rubella-mumps (MRM) vaccines have been applied to 887 and 148 children with various underlying diseases at the vaccine clinic of Osaka University Hospital between 1975 and 1985, respectively. Clinical reactions after mumps vaccination occurred in only 7 children (0.8%) and those after MRM vaccination in 28 children (19%), but their underlying diseases were not deteriorated by either vaccination. Clinical follow up study revealed that 2 of the 430 children immunized with mumps vaccine had contracted the disease during 7 year period and 2 of the 123 children immunized with MRM vaccine had contracted clinical mumps or rubella during 3 year period. The seroconversion rates after mumps vaccination were 70% and 61% by the hemagglutination inhibition (HI) test and neutralization (NT) test, respectively, while 94% by the fluorescent antibody to membrane antigen (FAMA) test. Those after MRM vaccination were 87% for measles, 96% for rubella by the HI test and 89% for mumps by the FAMA test. Serological follow up study revealed that antibodies elicited by mumps vaccination were sustained without substantial decline for at least 7 years. These results suggest that a live attenuated mumps and MRM vaccines are safe and effective in children with various underlying diseases.     

中国婴儿中脊灰母传抗体水平对两种疫苗免疫效果的影响

为了了解2月龄婴儿中针对脊髓灰质炎病毒的中和抗体水平,并探讨母传抗体对脊髓灰质炎减毒活疫苗(OPV)和灭活疫苗(IPV)免疫效果的影响。对416名2月龄婴儿分别接种OPV和IPV,采集免疫前后血清,用微量中和法检测血清中Ⅰ、Ⅱ、Ⅲ型脊髓灰质炎病毒中和抗体滴度,评价抗体GMT水平及4倍增长情况。检测结果显示,2月龄婴儿母传抗体Ⅰ、Ⅱ、Ⅲ型阳性率分别为45%、38.2%和17.5%,抗体GMT水平为9.0、8.1和5.2。经接种两组疫苗后,母传抗体阳性者与阴性者免后抗体GMT水平相比,OPV组无明显差异,IPV组阳性者略低于阴性者。在免前抗体滴度<1∶32人群中,OPV组免后抗体滴度4倍增长率及几何滴度增长倍数分别为:Ⅰ型93.6%、71.2;Ⅱ型98.2%、43.7;Ⅲ型91.7%、47.9;IPV组免后抗体滴度4倍增长率及几何滴度增长倍数分别为:Ⅰ型82%、9.4;Ⅱ型62.8%、5.1;Ⅲ型95.6%、11.7;在免前抗体滴度1∶32～1∶128人群中,OPV组Ⅰ型92.3%、23;Ⅱ型86.4%、13.9;Ⅲ型55.6%、4.1;IPV组Ⅰ型48%、2.5;Ⅱ型15%、0.9;Ⅲ型55.6%、2.7。目前中国2月龄婴儿免前脊灰抗体阳性率较高,尤其是Ⅰ、Ⅱ型。脊灰母传抗体对两种疫苗免疫效果有一定干扰,对IPV疫苗的影响较为明显。     

Humoral imunity to pertussis in children with diabetes of type 1

To determine the state of humoral immunity to pertussis in children with insulin-dependent diabetes, IgG antibodies to pertussis toxin (PT) were determined in blood serum samples by means of EIA. In a group of children aged up to 6 years the highest percentage (100%) received the complete course of vaccination against pertussis with Russian adsorbed DPT vaccine, containing whole-cell pertussis monovaccine, while in a group over 6 years the complete vaccination course (3 vaccinations and 1 revaccination) had 53.4% of children. Pertussis morbidity was considerably higher in nonvaccinated subjects than in children with 4-fold vaccination (p < 0.001). The coefficient of association (Q) was 0.84. Children of all age groups were found to have low and average titers of antibodies to PT. The regressive analysis showed a decrease in antibodies in persons completely immunized against pertussis by the age of 6 years old. The presence of antibodies in nonimmunized persons showed that cases of pertussis or carrier state took place among the population. High titers of antibodies, indicative of recent cases of pertussis, were registered in all age groups, but high titers of antibodies were registered mostly in the group of children over 13 years old (p < 0.05), which confirmed an increase in pertussis morbidity in adolescents. Thus, vaccination against pertussis effectively protected children with diabetes of type 1, aged up to 6 years. For more prolonged protection the vaccination and revaccination of children aged over 4 years old is necessary.     

Assessing the best time interval between doses in a two-dose vaccination regimen to reduce the number of deaths in an ongoing epidemic of SARS-CoV-2

The SARS-CoV-2 pandemic is a major concern all over the world and, as vaccines became available at the end of 2020, optimal vaccination strategies were subjected to intense investigation. Considering their critical role in reducing disease burden, the increasing demand outpacing production, and that most currently approved vaccines follow a two-dose regimen, the cost-effectiveness of delaying the second dose to increment the coverage of the population receiving the first dose is often debated. Finding the best solution is complex due to the trade-off between vaccinating more people with lower level of protection and guaranteeing higher protection to a fewer number of individuals. Here we present a novel extended age-structured SEIR mathematical model that includes a two-dose vaccination schedule with a between-doses delay modelled through delay differential equations and linear optimization of vaccination rates. By maintaining the minimum stock of vaccines under a given production rate, we evaluate the dose interval that minimizes the number of deaths. We found that the best strategy depends on an interplay between the vaccine production rate and the relative efficacy of the first dose. In the scenario of low first-dose efficacy, it is always better to vaccinate the second dose as soon as possible, while for high first-dose efficacy, the best strategy of time window depends on the production rate and also on second-dose efficacy provided by each type of vaccine. We also found that the rate of spread of the infection does not affect significantly the thresholds of the best window, but is an important factor in the absolute number of total deaths. These conclusions point to the need to carefully take into account both vaccine characteristics and roll-out speed to optimize the outcome of vaccination strategies.     

Reactogenicity of fluid compared with adsorbed diphtheria-pertussis-tetanus vaccine.

Shortly after the introduction of adsorbed diphtheria-pertussis-tetanus (DPT) vaccine in British Columbia the frequency of reports of reactions to the vaccine increased. As the reasons for the increase were not clear a study was carried out in five health units to compare the reactions to adsorbed DPT vaccine manufactured by Wyeth Ltd. and Connaught Laboratories Ltd. and fluid DPT vaccines manufactured by Connaught, all the vaccines being injected in the anterolateral thigh. From the responses on 1619 questionnaires that the parents of vaccinated children had completed it was found that the relative risk of a reaction was higher with the fluid than with the adsorbed Connaught vaccine (1.7 for redness and 1.8 for swelling on the day of vaccination but 1.0 for drowsiness and 1.3 for persistent crying). The size and duration of local redness and swelling were also greater with the fluid than with the adsorbed Connaught vaccines. The results with the Wyeth and Connaught vaccine were very similar. Only 10% of the parents said that there had been no reaction; 9% said that the reaction was severe, and 6% said that it was completely unacceptable. The overall frequency of local reactions was 86.1%.     

A randomised double-blind clinical trial of two yellow fever vaccines prepared with substrains 17DD and 17D-213/77 in children nine-23 months old

This randomised, double-blind, multicentre study with children nine-23 months old evaluated the immunogenicity of yellow fever (YF) vaccines prepared with substrains 17DD and 17D-213/77. YF antibodies were tittered before and 30 or more days after vaccination. Seropositivity and seroconversion were analysed according to the maternal serological status and the collaborating centre. A total of 1,966 children were randomised in the municipalities of the states of Mato Grosso do Sul, Minas Gerais and São Paulo and blood samples were collected from 1,714 mothers. Seropositivity was observed in 78.6% of mothers and 8.9% of children before vaccination. After vaccination, seropositivity rates of 81.9% and 83.2%, seroconversion rates of 84.8% and 85.8% and rates of a four-fold increase over the pre-vaccination titre of 77.6% and 81.8% were observed in the 17D-213/77 and 17DD subgroups, respectively. There was no association with maternal immunity. Among children aged 12 months or older, the seroconversion rates of 69% were associated with concomitant vaccination against measles, mumps and rubella. The data were not conclusive regarding the interference of maternal immunity in the immune response to the YF vaccine, but they suggest interference from other vaccines. The failures in seroconversion after vaccination support the recommendation of a booster dose in children within 10 years of the first dose.