Immunogenicity and efficacy of one dose measles-mumps-rubella (MMR) vaccine at twelve months of age as compared to monovalent measles vaccination at nine months followed by MMR revaccination at fifteen months of age

BACKGROUND AND METHODS: measles is a common cause of morbidity and mortality in developing countries. Although the measles-mumps-rubella vaccine (MMR) is currently in use in developed countries, monovalent measles vaccine (MV) is routinely recommended by World Health Organization (WHO) at 9 months of age in Turkey, as in many other developing countries. In this study, 442 Turkish children received MV at 9 months of age and were revaccinated with MMR vaccine at 15 months of age. In the second group 495 children received MMR at 12 months of age with no earlier measles vaccination. Antibodies were measured before the first vaccination and 6 weeks after the MMR. All children had been followed for occurrence of measles infection for 60 months. Two vaccination schedules were compared for immunogenicity and protection rates. CONCLUSIONS: seroconversion and clinical protection rates were significantly higher in children who received only MMR at 12 months of age than in children revaccinated at 15 months of age. Seroconversion rate for measles was 69.9% in children who received MMR at 12 months of age and 90.3% in children revaccinated at 15 months of age (P=0.0003). While there was no measles case in children who were revaccinated, 12 (2.7%) children in the first group acquired measles during the follow-up period. Vaccination at 12 months of age appeared to be better than the current national standard. The late elimination of maternal antibodies and the inhibitory effect of a weak antibody response after the first dose of vaccine at 9 months may explain the better immunogenicity and efficacy of the MMR vaccine given at 12 months of age.     

Measles susceptibility in children in Karachi, Pakistan

Measles, despite being vaccine preventable is still a major public health problem in many developing countries. We estimated the proportion of measles susceptible children in Karachi, the largest metropolitan city of Pakistan, one year after the nationwide measles supplementary immunization activity (SIA) of 2007-2008. Oral fluid specimens of 504 randomly selected children from Karachi, aged 12-59 months were collected to detect measles IgG antibodies. Measles antibodies were detected in only 55% children. The proportion of children whose families reported receiving a single or two doses of measles vaccine were 78% and 12% respectively. Only 3% of parents reported that their child received measles vaccine through the SIA. Among the reported single dose measles vaccine recipients, 58% had serologic immunity against measles while among the reported two dose measles vaccine recipients, 64% had evidence of measles immunity. Urgent strengthening of routine immunization services and high quality mass vaccination campaigns against measles are recommended to achieve measles elimination in Pakistan.     

合肥市适龄儿童麻疹疫苗强化免疫效果评价

目的了解合肥市适龄儿童麻疹疫苗(MV)强化免疫活动(SIA)效果及影响因素,为调整和实施消除麻疹策略提供参考。方法应用分层随机抽样法,选择合肥市社区疫苗接种门诊、幼儿园、小学、中学等作为研究点,分析8月龄～14岁儿童SIA前后麻疹抗体水平。SIA前后分别调查儿童340名和348名,应用描述统计方法,分析SIA前后麻疹流行状况。结果合肥市适龄儿童MV总体接种率为98.04%。SIA后麻疹抗体阳性率、几何平均滴度(GMT)均上升,麻疹抗体阳性率为91.38%。1～4岁组、≥3次免疫史者GMT分别为最高,Logistic多元回归分析显示,1次免疫史者抗体保护水平低。2010年麻疹发病率为0.81/10万,较2009年下降91.86%,发病年龄以婴儿为主,≥2次免疫史者病例构成比最低。结论在麻疹逐渐减弱流行阶段,需要规范适龄儿童首剂次、2剂次MV常规免疫,开展必要强化免疫,加强免疫规划和病例监测质量管理。     

Evaluation of an early two-dose measles vaccination schedule.

Vaccination at 6 months of age followed by routine revaccination is recommended when exposure of infants to measles is likely. Dade County, Florida, began this early two-dose schedule during a large epidemic in 1986-1987 (i.e., 22% of cases occurred in infants aged 6-11 months). This schedule was continued routinely in high-risk areas. The effect of an early two-dose schedule on measles prevention in the county was examined by comparing measles vaccination coverage and epidemiology before (1985-1987) and after (1988-1996) the schedule became routine. To assess serologic response, seroprevalence of measles antibody among children aged 4-6 years in 1995 was examined. To evaluate vaccine effectiveness, a case-control study was conducted among preschool-aged children. Among those aged 2 years, vaccination coverage with > or =1 dose increased from 75% to 94% in 1996. The number of annual cases declined, and endemic measles transmission reportedly ended after 1993. Seroprevalence of plaque reduction neutralization antibody (titer > 1:120) among those receiving vaccination according to an early two-dose schedule and a single dose at age > or =12 months was 94% (95% confidence interval: 89, 98) and 98% (95% confidence interval: 95, 100). In these groups, vaccine effectiveness was comparably high. Early two-dose measles vaccination is associated with improved coverage and a comparably high level of humoral immunity and clinical protection as a single dose at age > or =12 months. This strategy can be useful in areas at high risk for measles among infants.     

Development and durability of measles antigen-specific lymphoproliferative response after MMR vaccination

The correlates of long-term protection from measles infection are poorly understood. We followed the development of measles-specific antibody and lymphoproliferative (LP) responses in 60 children for 6 months after MMR vaccination. Prevaccine plaque reduction neutralization antibody (PRN Ab) values were low (mean+/-SEM 9.9+/-1. 1). Ninety-three percent (56/60) had excellent PRN values at 6 months (PRN 1816+/-207). Prevaccine LP activity was also low (stimulation index (SI)=1.4+/-0.1) but increased rapidly (SI 10. 7+/-4.5 at 2-3 weeks; p<0.05). However, only 61% (37/60) of the children had both significant cellular and antibody responses (SI>/=3 and PRN>/=120: Ab(hi)CMI(hi)). One child had a strong LP response (SI=6.7) despite little antibody production (PRN=19 at 6 months: Ab(lo)CMI(hi)). We also conducted a cross-sectional study in a separate group of 87 children 5-13 years after MMR vaccination. PRN values >/=120 were present in most children at 5-8 (n=28) and 9-13 years (n=59) after vaccination (PRN 550+/-120 and 360+/-60, respectively) but a significant minority had either undetected or 'subprotective' values (29 and 34%, respectively). LP responses (SI>/=3) were detectable in 19/28 (66%) and 36/59 (56%) of the children 5-8 and 9-13 years after vaccination (SI 11.4+/-2.4 and 7. 75+/-1.9, respectively). Almost two thirds (18/28) of the children in the cross-sectional study with low or absent antibody titers (PRN 41+/-6) had strong LP responses to measles antigens (SI 6.8+/-1.3). These data suggest that LP responses may be better sustained than antibody titers in some children. The susceptibility of Ab(lo)CMI(hi) children to infection and the value of the early LP response for predicting the durability of immunity remain to be determined.     

Measles antibody responses after early two dose trials in Guinea-Bissau with Edmonston-Zagreb and Schwarz standard-titre measles vaccine: better antibody increase from booster dose of the Edmonston-Zagreb vaccine

In Guinea-Bissau, children were randomised at 6 months of age to receive either two doses of standard-titre measles vaccine at 6 and 9 months of age or an inactivated polio vaccine at 6 months and standard-titre measles vaccine at 9 months of age. During the first 5 months, children received Edmonston-Zagreb (EZ) vaccine and during the following 11 months, the Schwarz (SW) vaccine. Five percent of the mothers, 74% of children at 6 months of age, and 92% of unvaccinated children at 9 months of age had unprotective levels (<125 mIU/ml) of measles antibodies. Among children receiving EZ vaccine, 1% were unprotected at 18 months of age after either two (3/240) or one (3/211) doses of vaccine, the geometric mean measles antibody titre (GMT) being approximately 1550 mIU/ml in both groups. Among those receiving SW vaccine 9% (34/365) and 3% (9/310) were unprotected at 18 months of age in the two-dose and the one-dose groups (RR = 3.21 (95% confidence interval (CI) 1.56-6.58)), respectively. The GMT was higher after one dose of SW vaccine at 9 months of age (2491 mIU/ml) than after two doses of SW vaccine (1125 mIU) (P < 0.001). In the EZ vaccine group, there was no significant difference in antibody level for children vaccinated in the presence of high or low levels of maternal antibodies, whereas there was a marked difference in the SW group. The second EZ vaccine induced a significant antibody increase between 9 months of age (1191 mIU) and 18 months of age (1602 mIU, P=0.011), whereas antibody levels tended to decline from 9 months (1243 mIU) to 18 months of age (998 mIU, P = 0.124) after the second dose of SW vaccine. Conclusively, after two doses of EZ measles vaccine more children were protected at 18 months of age than after two doses of SW. One dose of SW provided the highest antibody response, but a higher proportion of unprotected than one or two doses of EZ. The EZ vaccine was less sensitive to maternal antibodies, and able to increase the antibody response by revaccination, while the second SW vaccine resulted in an unchanged or lower antibody response.     

Measles supplemental immunization activities improve measles vaccine coverage and equity: Evidence from Kenya, 2002

OBJECTIVES: To compare the measles vaccine coverage achieved through the routine vaccination program with that achieved during the 2002 supplemental immunization activity (SIA) at the national and provincial level, the percentage of previously unvaccinated children (zero-dose children) reached during the SIA, and the equity of measles vaccine coverage among children aged 9-23 months in Kenya. METHODS: Using data from a post-SIA coverage survey conducted in Kenya, we compute routine and SIA measles vaccine coverage and the percent of zero-dose children vaccinated during the SIA at the national and provincial level. Nationwide and for each province, we use the concentration index (CI) to measure equity of measles vaccine coverage. RESULTS: The SIA improved both coverage and equity, achieving significantly higher coverage in all provinces with routine measles vaccination coverage less than 80%, reached a large percentage of zero-dose children in these provinces, and reached more children belonging to the poorest households. CONCLUSION: Overall, by improving both measles vaccine coverage and equity in Kenya, the 2002 SIA reduced the gap in immunity between rich and poor households. Measles SIAs provide an ideal platform for delivering other life-saving child health interventions.     

麻疹疫苗高覆盖率背景下麻疹流行特征的变化与免疫策略调整必要性的探讨

目的探讨控制麻疹的策略和措施。方法对芜湖市1996～2005年麻疹的发病情况、麻疹爆发疫情、麻疹疫苗接种率、麻疹疫苗强化免疫等进行综合分析。结果1996～2005年，芜湖市麻疹疫苗报告接种率为98．47％，儿童疫苗免疫后抗体阳性率为95．77％。期间共报告麻疹病例697例，年平均发病率为3．19／10万，其中爆发疫情11起，爆发病例占总数的16．5％，其中有免疫史者占72．3％。与全国大多数地区相似，小于8个月和15岁以上年龄组的发病有增高趋势。根据国内文献资料，近年来全国部分地区13992例麻疹病例中，有麻疹疫苗免疫史的为3921例（28．0％），无免疫史的4753例（34．0％），免疫史不祥的5318例（38．0％）。结论有较好的计划免疫基础并不能避免麻疹的爆发，为达到消除麻疹的目标，除需要扎实开展儿童免疫规划基础工作外，还需对我国现行的麻疹免疫策略及免疫程序进行调整，建立新的成人免疫规划体系，适时研究开发更有效的麻疹疫苗毒株提高疫苗的免疫效力。     

Supplemental measles vaccine antibody response among HIV-infected and -uninfected children in Malawi after 1- and 2-dose primary measles vaccination schedules

BackgroundThe long-term antibody response to measles vaccine (MV) administered at age 6 months with or without subsequent doses is not well documented.MethodsMeasles serum antibody responses were evaluated after a supplemental dose of measles vaccine (sMV) administered at a median age of 20 months among Malawian children who had previously received 2 doses of measles vaccine (MV) at ages 6 and 9 months (HIV-infected and random sample of HIV-uninfected) or 1 dose at age 9 months (random sample of HIV-uninfected). We compared measles antibody seropositivity between groups by enzyme linked immunoassay and seroprotection by plaque reduction neutralization geometric mean concentrations.ResultsOf 1756 children enrolled, 887 (50.5%) received a sMV dose following MV at 9 months of age and had specimens available after sMV receipt, including 401 HIV-uninfected children who received one MV dose at 9 months, 464 HIV-uninfected and 22 HIV-infected children who received two doses of MV at ages 6 and 9 months. Among HIV-uninfected children, protective levels of antibody were found post sMV in 90–99% through ages 24–36 months and were not affected by MV schedule. Geometric mean concentration levels of measles antibody were significantly increased post-sMV among those HIV-uninfected children previously non-responsive to vaccination. Among HIV-infected children, the proportion seroprotected increased initially but by 9 months post-sMV was no higher than pre-sMV.ConclusionsOur findings support early 2-dose MV to provide measles immunity for young infants without risk of interference with antibody responses to subsequent MV doses administered as part of SIAs.     

北京市外来务工人员麻疹和流脑疫苗接种状况分析

目的了解北京市外来务工人员麻疹疫苗（MV）、流脑疫苗（MPV）接种状况,评估流动人口接种政策的实施情况。方法采用方便抽样方法,对804名无本市户籍、来京居住3个月以上、年龄15—45岁的外来务工人员进行问卷调查,采用描述性分析和X^2检验的数据分析方法。结果调查对象自报麻疹和流脑疫苗累计接种率分别为5．2％和6．8％。有11．6％和4．5％的调查对象较好地掌握了麻疹、流脑知识,28．1％的调查对象知晓为外来务工人员组织的免疫接种活动,65．8％的调查对象对疫苗安全的信任度较高。来京居住4年以上（麻疹7．4％;流脑9．9％）、了解接种活动（麻疹14．2％;流脑18．2％）、有正式工作合同（流脑9．7％）和对疫苗安全信任度较高（麻疹6．6％;流脑8．3％）的调查对象的自报接种率较高。而白天工作（麻疹4．8％;流脑6．5％）或收入较高（麻疹2．5％;流脑3．1％）的调查对象则接种率较低。结论针对来京务工人员麻疹、流脑疫苗接种活动参与率低的状况,建议免疫服务机构结合其工作生活环境的特点,加大对流动人口免疫接种服务递送的力度及灵活度,加强对疫苗接种的宣传,逐步提高来京务工人员接种率。     

麻疹母传抗体水平及6～8月龄接种麻疹疫苗的免疫效果监测

[目的]了解8月龄以下婴儿麻疹母传抗体水平及6～8月龄婴儿接种麻疹疫苗的免疫效果和安全性,探讨控制小月龄婴儿麻疹的免疫策略。[方法]在南昌市的12个县(区)随机抽取0～8月龄婴儿各70余名,监测麻疹母传抗体;对6～8月婴儿初免麻疹疫苗后免疫效果及安全性观察,采用酶联免疫吸附试验检测免前和免后1个月的麻疹IgG抗体滴度。[结果]8月龄以下婴儿母传抗体几何平均滴度为1︰209,各月龄组抗体几何平均滴度均未达保护水平;6月龄、7月龄、8月龄初免后GMT分别为1︰1407、1︰1897、1︰2410,初免前后GMT差异有统计学意义(P﹤0.05),初免后3组的阳性率均≥90%,免疫成功率﹥85%,接种MV未出现异常反应,提示6月龄的MV初免程序是可行的;但6、7、8月龄3组间免疫成功率差异有统计学意义(P﹤0.05),免前母传抗体阴性和阳性的免疫成功率差异有统计学意义(P﹤0.05),提示婴儿母传抗体的存在对MV的免疫成功率有干扰作用。[结论]婴儿麻疹母传抗体滴度均较低,无有效保护作用;6足月后接种麻疹疫苗安全有效。建议进行育龄妇女孕前接种MV和提前婴儿MV初免时间的成本效益研究,制定安全有效的免疫策略,减少小月龄婴儿麻疹发病率。     

A school-based measles outbreak: the effect of a selective revaccination policy and risk factors for vaccine failure

Persons who received measles vaccine between 12 and 14 months of age have been found to be at increased risk of measles compared with those vaccinated at greater than or equal to 15 months of age. Because of this, in 1987 the Immunization Practices Advisory Committee of the US Public Health Service recommended that, during measles outbreaks, revaccination of persons vaccinated at 12-14 months of age be considered. During a school-based outbreak in New Mexico in 1987, the authors evaluated the effect of a mandatory revaccination policy in affected schools. Before the effect of revaccination, the overall attack rate in persons vaccinated at greater than or equal to 12 months of age was 4.1 cases/1,000 students; afterward, the risk was significantly reduced by 73%, to 1.1/1,000 students. The attack rate among students targeted for revaccination declined 100%, compared with 41% among those not revaccinated. Overall, attack rates were significantly lower in schools conducting revaccination early compared with schools holding later revaccination. In a retrospective cohort study of single-dose vaccines in one school, age at vaccination was not associated with risk of disease; however, persons vaccinated greater than or equal to 10 years before the outbreak were at increased risk, independently of age at vaccination. Revaccination of persons whose most recent vaccination was between 12 and 14 months of age appeared to control transmission in this outbreak. Further studies are needed to confirm these observations and to evaluate the effect of other revaccination efforts during outbreaks.     

Progress in measles control--Zambia, 1999-2004

Zambia, a southern African country with estimated population of 11.6 million in 2005, reported 1,698-23,518 measles cases annually during 1991-1999. During that period, measles was considered one of the five major causes of morbidity and mortality among children aged <5 years. During 1999-2004, the challenge of controlling measles led Zambia to try several strategies in succession. In addition to a single dose of measles vaccine offered at age 9 months through routine services, in 1999, measles supplemental immunization activities (SIAs) targeting children aged 9 months-4 years were held in four urban centers. Those activities were followed in 2000 by a subnational measles SIA targeting children aged 9 months-4 years in approximately half of the country's 72 districts. In 2003, Zambia adopted a strategy of accelerated measles control that included strengthening routine vaccination, providing a second opportunity for measles immunization for all children, and conducting case-based surveillance. As part of this strategy, a nationwide measles SIA targeting all children aged 6 months-14 years was conducted in 2003. This report summarizes progress in measles control in Zambia during 1999--2004, as measured through surveillance data, which demonstrates a marked reduction in measles transmission after the 2003 SIA.     

Measles vaccine efficacy during an outbreak in a highly vaccinated population: incremental increase in protection with age at vaccination up to 18 months.

During a large measles outbreak in Quebec City in 1989, two investigations conducted in parallel evaluated the relative risk of measles and measles vaccine effectiveness with respect to age at vaccination. The study was a school-based case-control study including 563 cases and 1126 classmate controls. The second was a cohort study of the siblings of school cases including 493 siblings aged between 1 and 19 years. The relative risks (RR) of measles were similar in both settings and the trend towards increased vaccine efficacy with increasing age at vaccination was highly significant (P < 0.001). Vaccine efficacy rose from 85% in children vaccinated at 12 months of age to > or = 94% in those vaccinated at 15 months and older. Even for children vaccinated at or after 18 months of age, the RR of measles was reduced when compared with children vaccinated between 15 and 17 months of age (RR 0.61, CI 95% 0.33-1.15). Small changes in the timing of initial measles vaccination can have a major impact on vaccine efficacy.     

Measles immunity in the first year after birth and the optimum age for vaccination in Kenyan children: Collaborative study by the Ministry of Health of Kenya and the World Health Organization*

There is still controversy about the optimum age for measles vaccination in developing countries, where the incidence of measles infection is higher in the first few months of life than it is in developed countries. This study was undertaken to collect reliable data in order to determine the optimum age for mass vaccination programmes. Haemagglutination inhibition (HI) antibodies were titrated periodically from birth to one year of age in children who were given the vaccine at different ages, between 5 and 9 months. It was found that 90% of children no longer have their maternal antibodies at 7-8 months of age, precisely at the period that the incidence of measles begins to rise sharply. Almost all children showed HI seroconversion when vaccinated at 71/2 months (or later, but not before), even if a low level of maternal antibody still persisted when the vaccine was given. These data show that there is an advantage in carrying out measles vaccination at 71/2 months of age in countries with conditions similar to that of Kenya. The duration of post-vaccinal immunity beyond one year of age has not been studied, but it can reasonably be expected that immunity after one vaccination can last for at least 3-5 years, thus exceeding the period when African children are most exposed to malnutrition.     

Comparison of AIK-C measles vaccine in infants at 6 months with Schwarz vaccine at 9 months: a randomized controlled trial in Ghana.

In a randomized controlled trial in a measles endemic area, standard-dose (4.0 log10pfu) AIK-C measles vaccine administered at 6 months of age was compared to standard-dose Schwarz vaccine (3.7log10pfu) given at 9 months. Seroconversion rates at 3 and 6 months after immunization in the two groups were comparable and similar. The geometric mean titres achieved were, however, significantly higher in the Schwarz group (P < 0.05). No immediate serious side-effects were observed with either vaccine. We conclude that standard-dose AIK-C measles vaccine can be recommended for measles immunization in children below 9 months of age, especially in highly endemic and high-risk areas in developing countries.     

深圳市南山区1990～2001年麻疹流行病学特征分析

为进一步了解深圳市南山区麻疹流行情况 ,为加速控制麻疹提供科学依据 ,对 1990～ 2 0 0 1年麻疹监测资料进行分析。结果显示 :麻疹发病以外来流动人口为主 ,占 81.9%;发病季节高峰在 3～ 6月 ,每隔 5～ 6年流行一次 ;1996～ 2 0 0 1年麻疹发病年龄主要是 <5岁儿童 ( 2 8.3 %)和 15～ 30岁成人 ( 42 .6 %)。麻疹流行的主要原因是人口流动、未免疫和未复种麻疹疫苗 (MV)人群的积聚。因此 ,加强MV初免和复种工作 ,提高接种质量、麻疹监测和流动人口的免疫覆盖率 ,开展对特定人群的免疫 ,是控制麻疹发病的有效措施.     

2009年广东省8月龄至14岁儿童麻疹疫苗强化免疫活动分析

目的分析总结2009年3—4月广东省麻疹疫苗（MV）强化免疫活动的有关数据,为制定达到消除麻疹目标策略提供依据。方法该次强化免疫对象为广东省内8月龄至14周岁儿童（包括流动儿童）,无论既往有无接种史或患病史,1个月内均接种1剂次麻疹疫苗。通过收集整理广东省MV强化免疫报表数据和现场评估等情况,采用流行病学方法进行分析。结果全省摸底登记8月龄至14周岁儿童共20 437 255人,报告接种数为19 952 519人,报告接种率为97.63%,强化免疫活动前麻疹疫苗调查接种率为71.66%,与强化免疫活动后调查接种率（98.10%）比较,差异有统计学意义（P〈0.01）。活动前儿童家长知晓率为91.86%,活动后期知晓率为98.48%,差异有统计学意义（P〈0.01）;麻疹疫苗强化免疫疑似预防接种异常反应报告发生率为4.21/10万;麻疹疫苗强化免疫后,2009年5—12月麻疹发病数较去年同期下降92.59%,麻疹发病率从2008年的16.10/10万下降到2009年的2.22/10万。结论麻疹疫苗强化免疫是控制和消除麻疹的有效措施,政府主导、多部门配合、声势浩大的宣传发动和良好的组织实施是强化免疫成功的关键。     

Linked vaccination coverage surveys plus serosurveys among Ethiopian toddlers undertaken three years apart to compare coverage and serologic evidence of protection in districts implementing the RED-QI approach

In low and middle-income countries, estimating the proportion of vaccinated toddlers in a population is important for controlling vaccine-preventable diseases by identifying districts where immunization services need strengthening. Estimates measured before and several years after specific interventions can assess program performance. However, employing different methods to derive vaccination coverage estimates often yield differing results.MethodsLinked vaccination coverage surveys and seroprotection surveys performed among ~300 toddlers 12–23 months of age in districts (woredas), one per region, of Ethiopia (total, ~900 toddlers) in 2013 to estimate the proportion vaccinated with tetanus toxoid (a proxy for pentavalent vaccine) and measles vaccine. The surveys were followed by implementation of the Reaching Every District using Quality Improvement (RED-QI) approach to strengthen the immunization system.Linked coverage/serosurveys were repeated in 2016 to assess effects of the interventions on vaccination coverage. Indicators included “documented coverage” (vaccination card and/or health facility register records) and “crude coverage” (documented plus parent/caretaker recall for children without cards). Seroprotection thresholds were IgG-ELISA tetanus antitoxin ≥0.05 IU/ml and plaque reduction neutralization (PRN) measles titers ≥120 mIU/ml.FindingsImproved markers in 2016 over 2013 include coverage of pentavalent vaccination, vaccination timeliness, and fewer missed opportunities to vaccinate. In parallel, tetanus seroprotection increased in the 3 woredas from 59.6% to 79.1%, 72.9% to 83.7%, and 94.3 to 99.3%. In 2015, the Ethiopian government conducted supplemental measles mass vaccination campaigns in several regions including one that involved a project woreda and the campaign overlapped with the RED-QI intervention timeframe; protective measles PRN titers there rose from 31.0% to 50.0%.InterpretationThe prevalence of seroprotective titers of tetanus antitoxin (stimulated by tetanus toxoid components within pentavalent vaccine) provides a reliable biomarker to identify children who received pentavalent vaccine. In the three study woredas, the RED-QI intervention appeared to improve immunization service delivery, as documented by enhanced pentavalent vaccine coverage, vaccination timeliness, and fewer missed vaccination opportunities. A measles mass vaccination campaign was followed by a markedly increased prevalence of measles PRN antibodies. Collectively, these observations suggest that wider implementation of RED-QI can strengthen immunization, and periodic linked vaccination surveys/serosurveys can monitor changes.     

Added value of the measles-rubella supplementary immunization activity in reaching unvaccinated and under-vaccinated children,a cross-sectional study in five Indian districts, 2018–20

IntroductionSupplementary immunization activities (SIAs) aim to interrupt measles transmission by reaching susceptible children, including children who have not received the recommended two routine doses of MCV before the SIA. However, both strategies may miss the same children if vaccine doses are highly correlated. How well SIAs reach children missed by routine immunization is a key metric in assessing the added value of SIAs.MethodsChildren aged 9 months to younger than 5 years were enrolled in cross-sectional household serosurveys conducted in five districts in India following the 2017–2019 measles-rubella (MR) SIA. History of measles containing vaccine (MCV) through routine services or SIA was obtained from documents and verbal recall. Receipt of a first or second MCV dose during the SIA was categorized as “added value” of the SIA in reaching un- and under-vaccinated children.ResultsA total of 1,675 children were enrolled in these post-SIA surveys. The percentage of children receiving a 1st or 2nd dose through the SIA ranged from 12.8% in Thiruvananthapuram District to 48.6% in Dibrugarh District. Although the number of zero-dose children prior to the SIA was small in most sites, the proportion reached by the SIA ranged from 45.8% in Thiruvananthapuram District to 94.9% in Dibrugarh District. Fewer than 7% of children remained measles zero-dose after the MR SIA (range: 1.1–6.4%) compared to up to 28% before the SIA (range: 7.3–28.1%).DiscussionWe demonstrated the MR SIA provided considerable added value in terms of measles vaccination coverage, although there was variability across districts due to differences in routine and SIA coverage, and which children were reached by the SIA. Metrics evaluating the added value of an SIA can help to inform the design of vaccination strategies to better reach zero-dose or undervaccinated children.