Cluster sampling methodology to evaluate immunization coverage

BACKGROUND Immunization is a key component of primary health care and an indisputable human right.Vaccines are critical to the prevention and control of infectious disease outbreaks.The coronavirus disease 2019(COVID-19)pandemic and associated disruptions over the past two years have strained the health systems,with many children missing out on essential childhood vaccines.AIM To evaluate the immunization coverage among 12-23-month-old children in the rural areas of Community Health Centre(CHC)Dighal and to determine the factors influencing the existing immunization coverage.METHODS A coverage evaluation survey was conducted according to the 30-cluster sampling technique,which is the standard methodology for such surveys devised by World Health Organization.A total of 300 children aged 12-23 months were included,whose immunization details were noted from their immunization cards.RESULTS Full immunization rate was noted in 86.7%of the children,with partial and non-immunized children accounting for 9%and 4.3%respectively.The full immunization dropout rate was 4.2%.The common reasons for partial or non-immunization were family problem including illness of mother,vaccine not being available and child being ill.Place of birth(P=0.014)and availability of immunization card(P<0.001)were significant predictors of the immunization status.Since the study was conducted in 2020/2021,health services were disrupted due to the COVID-19 lockdown.CONCLUSION Due to the coverage being higher than the national average,it was concluded that the immunization coverage was optimal and not affected by the COVID-19 pandemic.

Rethinking Strategies to Address Inequity in Immunization Services towards Achieving Universal Immunization Coverage (UIC) in Karachi, Pakistan

Karachi, the largest city in Pakistan, having high population growth and a complex health care environment, has highest density of unimmunized (zero dose) and under-immunized children. The main reasons of low immunization coverage in Karachi were lack of governance and accountability in a duplicative and fragmented health management structure, weak and inequitable immunization services, and lack of demand and trust among people for immunization services. The Expanded Programme on Immunization (EPI), Ministry of Health (MOH) in Sindh Province spearheaded a structured and collaborative process to develop strategies for addressing inequity in immunization services towards achieving Universal Immunization Coverage (UIC) in Karachi. The process included a situation analysis with gathering quantitative and qualitative information on the root causes of zero-dose and inequity of the immunization services. The strategies and interventions were developed with multi-layer input and feedback of the stakeholders and partners, and focusing primarily to address gaps in three program areas: governance, leadership and accountability;immunization service delivery;and building demand and trust among the people. The interventions were further prioritized for high-risk areas;identified based on maximum number zero-dose children, presence of large slum areas, measles outbreak and on-going circulation of wild poliovirus. Finally, costing for the Roadmap activities was done through consultation with partners and aligning domestic and external (donor) resources. In this paper, we have highlighted the unique process the Sindh Government undertook in collaboration with the stakeholders and partners to develop strategies and interventions for addressing inequity in urban immunization services in Karachi towards achieving Universal Immunization Coverage (UIC). Similar processes can be adapted, as a potential model, for developing strategies to achieve universal health coverage in the cities of Pakistan and in other countries.

Forecasting Measles Immunization Coverage Using ARIMA Model

This study aimed to find a model to forecast monthly measles immunization coverage using Autoregressive Integrated Moving Average (ARIMA). The monthly registered data for measles immunization coverage from January 2014 to December 2018 were used for the development of the model. The best model with the smallest Normalized Bayesian Information Criterion (BIC) of 8.673 is ARIMA (0, 1, 0). ARIMA (0, 1, 0) was used to forecast the monthly measles immunization coverage for the next 36 months from January 2018 to December 2020. The results obtained prove that this model can be used for forecasting future immunization coverage and will help decision-makers to establish strategies, priorities, and proper use of immunization resources.

Avoiding the Will O’ the Wisp: Challenges in Measuring High Levels of Immunization Coverage with Precision

There have been tremendous improvements in immunization coverage since the Expanded Programme on Immunization was launched. We highlight inherent challenges in measuring immunization coverage with precision as coverage levels increase due to the sensitivity of coverage to the accuracy of target population estimates. In fact, when comparing across groups at high levels of coverage, error in target population estimates can obscure differences in immunization coverage.

High Immunization Coverage but Delayed Immunization Reflects Gaps in Health Management Information System (HMIS) in District Kangra, Himachal Pradesh, India—An Immunization Evaluation

Background: Complete and timely childhood immunization is one of the most cost-effective interventions in improving child survival in developing countries. Computerized HMIS has been recently introduced to collect aggregated data on service beneficiaries in Himachal Pradesh. HMIS provides coverage estimates for immunization while information on timeliness is currently not available. Hence we conducted a study to validate coverage and assess the timeliness of immunization in Kangra District of Himachal Pradesh. We surveyed mothers (224) of children aged 12 - 23 months (as on January 2008) and selected 32 clusters in the district between January and March 2008. Design/Methods: We conducted a cross sectional survey and selected 32 clusters by probability proportional to size method whereas seven eligible children per cluster were randomly selected. We interviewed mothers using a structured interview schedule, examined immunization card & looked for Bacillus Calmette Guierre (BCG) Scar. Vaccination after 30 days from national schedule was considered “delayed”. We computed proportions of children completely immunized, immunization delayed, frequency of reasons for delay and 95% Confidence Interval (CI) for significance of associated factors. We conducted a case control analysis of factors associated with timely immunization by taking timely immunized children as cases and delayed immunized ones as controls. Results/Outcome: Reported coverage was universal (100%). Validated full immunization coverage was 94.2% by card/record & 99% by history. Only 29.5% (CI = 20.6% - 37.4%) of children were fully immunized as per schedule (delay less than 30 days). Median delay was 21 days for BCG, 28 days for Diptheria Pertussis Tetanus (DPT 3) and 25 days for measles. Among those with delayed vaccinations, reasons were forgetfulness (36%), lack of correct knowledge (27%) & mother gone to parents’ home (27%) & insufficient children in a camp to open full dose BCG vial (22%). Our case control analysis of timely vaccinated versus delayed vaccination revealed that “precall” (reminder) was significantly [OR = 0.1, CI = 0.2 - 0.5] protective against delayed vaccination. Logistic Regression of delay > 30 days revealed that having returned unimmunized from immunization camp earlier due to insufficient children to open vaccine vial (because of high wastage factor) was significantly associated with delayed immunization (p = 0.0000), while knowledge of date of immunization camp was significantly protective from delayed immunization (p = 0.0026). 68% of the children were having at least one immunization delayed over 30 days from recommended schedule, while the proportion of children whose immunization was delayed by over 90 days was 9.4%. Conclusions: Validated field coverage estimates are lower than reported which can be due to inclusion of children of migrants in numerator & not in the denominator. High proportion of children (>70%) were delayed, suggesting implications for WHO’s strategy of measles control & national Tuberculosis (TB) control programmes, as 4.5% of them had suffered from measles. To avoid delays we recommend (i) use of mono dose vials for BCG;(ii) precall notice to mothers;(iii) modification of HMIS software to track immunization status and timeliness of individual beneficiaries rather than aggregate numbers.

Improving Routine Immunization Coverage Through Optimally Designed Predictive Models

Routine immunization(RI)of children is the most effective and timely public health intervention for decreasing child mortality rates around the globe.Pakistan being a low-and-middle-income-country(LMIC)has one of the highest child mortality rates in the world occurring mainly due to vaccine-preventable diseases(VPDs).For improving RI coverage,a critical need is to establish potential RI defaulters at an early stage,so that appropriate interventions can be targeted towards such populationwho are identified to be at risk of missing on their scheduled vaccine uptakes.In this paper,a machine learning(ML)based predictivemodel has been proposed to predict defaulting and non-defaulting children on upcoming immunization visits and examine the effect of its underlying contributing factors.The predictivemodel uses data obtained from Paigham-e-Sehat study having immunization records of 3,113 children.The design of predictive model is based on obtaining optimal results across accuracy,specificity,and sensitivity,to ensure model outcomes remain practically relevant to the problem addressed.Further optimization of predictive model is obtained through selection of significant features and removing data bias.Nine machine learning algorithms were applied for prediction of defaulting children for the next immunization visit.The results showed that the random forest model achieves the optimal accuracy of 81.9%with 83.6%sensitivity and 80.3%specificity.The main determinants of vaccination coverage were found to be vaccine coverage at birth,parental education,and socioeconomic conditions of the defaulting group.This information can assist relevant policy makers to take proactive and effective measures for developing evidence based targeted and timely interventions for defaulting children.

Thinking Out-of-Box in Addressing Communication and Service Delivery Challenges: Use of a Traditional Communication Method for Improving Immunization Coverage in Remote Rural Hard-to-Reach Areas of India

Sirmaur district in the state of Himachal Pradesh in India is a hard-to-reach area situated in the western Himalayas having an extreme landscape with snow-laden mountains and extensive river systems that makes the delivery of immunization services extremely challenging. Vaccinators needed a long walk through the hilly terrain to reach outreach sites. Community mobilizers were unable to go house to house to inform the caregivers to bring children to the site for vaccination. Caregivers were unaware when the vaccinators arrive at the site. As a result, many children missed vaccination or were not vaccinated timely. Age-appropriate vaccination coverage (according to national immunization schedule) in the Sirmaur district was the lowest in the state. Thinking out-of-box to address the communication barriers with the caregivers, the traditional drum beating was used, for the first time in India, in two blocks of the Sirmaur district (Rajpura and Shillai). The initiative was planned and implemented by the district health system with the support of the local community leaders. An exit interview was conducted to know the reach of the drum beating to caregivers, and a baseline and end line household survey was conducted to know the outcome of the initiative on age-appropriate vaccination coverage. Analysis of exit interviews data indicated a very high reach of a drum beating to the caregivers;more than 97% of caregivers in Rajpura and 100% in Shillai heard drum beating, and almost 95% of caregivers in Rajpura and 98% in Shillai knew the purpose of drum beating. Analysis of immunization data from baseline and end line surveys showed improvement in age-appropriate vaccination coverage for all vaccines in Rajpura (by 2.2% for BCG, 15.3% for Pentavalent 1, 14.9% for Pentavalent 2, 14.1% for Pentavalent 3, and 6.5% for Measles/MR). In Shillai, age-appropriate vaccination coverage improved for Pentavalent 1 (by 3.4%), Pentavalent 2 (by 5%) and Measles/MR (by 1.7%). In addition, dropout rates were reduced in both the blocks, particularly in Rajpura Pentavalent 1 to Measles dropout rate was reduced by 13.5%. Both health workers and community leaders had positive perceptions of the drum beating initiative. However, another important lesson learned from the initiative was that both the access and demand-side barriers need to be addressed for the desired improvement of age-appropriate immunization coverage. In Shillai, there was lower coverage improvement and a reduction in dropout rates attributed to vacant positions of vaccinators that caused an issue with access to immunization services to people.

Immunization coverage,knowledge,satisfaction,and associated factors of non-National Immunization Program vaccines among migrant and left-behind families in China:evidence from Zhejiang and Henan provinces

Background Migrant and left-behind families are vulnerable in health services utilization,but little is known about their disparities in immunization of non-National Immunization Program(NIP)vaccines.This study aims to evaluate the immunization coverage,knowledge,satisfaction,and associated factors of non-NIP vaccines among local and migrant families in the urban areas and non-left-behind and left-behind families in the rural areas of China.Methods A cross-sectional survey was conducted in urban areas of Zhejiang and rural areas of Henan in China.A total of 1648 caregivers of children aged 1-6 years were interviewed face-to-face by a pre-designed online questionnaire,and their families were grouped into four types:local urban,migrant,non-left-behind,and left-behind.Non-NIP vaccines includedHemophilus influenza b(Hib)vaccine,varicella vaccine,rotavirus vaccine,enterovirus 71 vaccine(EV71)and 13-valent pneumonia vaccine(PCV13).Log-binomial regression models were used to calculate prevalence ratios(PRs)and 95%confidence intervals(CIs)for the difference on immunization coverage of children,and knowledge and satisfaction of caregivers among families.The network models were conducted to explore the interplay of immunization coverage,knowledge,and satisfaction.Logistic regression models with odds ratios(ORs)and 95%CIs were used to estimate the associated factors of non-NIP vaccination.Results The immunization coverage of all non-NIP vaccines and knowledge of all items of local urban families was the highest,followed by migrant,non-left-behind and left-behind families.Compared with local urban children,thePRs(95%CIs)for getting all vaccinated were 0.65(0.52-0.81),0.29(0.22-0.37)and 0.14(0.09-0.21)among migrant children,non-left-behind children and left-behind children,respectively.The coverage-knowledge-satisfaction network model showed the core node was the satisfaction of vaccination schedule.Non-NIP vaccination was associated with characteristics of both children and caregivers,including age of children(>2 years-OR:1.69,95%CI:1.07-2.68 for local urban children;2.67,1.39-5.13 for migrant children;3.09,1.23-7.76 for non-left-behind children);and below caregivers’characteristics:family role(parents:0.37,0.14-0.99 for non-left-behind children),age(≤35 years:7.27,1.39-37.94 for non-left-behind children),sex(female:0.49,0.30-0.81 for local urban children;0.31,0.15-0.62 for non-left-behind children),physical health(more than average:1.58,1.07-2.35 for local urban children)and non-NIP vaccines knowledge(good:0.45,0.30-0.68 for local urban children;7.54,2.64-21.50 for left-behind children).Conclusions There were immunization disparities in non-NIP vaccines among migrant and left-behind families compared with their local counterparts.Non-NIP vaccination promotion strategies,including education on caregivers,and optimization of the immunization information system,should be delivered particularly among left-behind and migrant families.

A Comparison of National Immunization Programme Target Population Estimates with Data from an Independent Source and Differences in Computed Coverage Levels for the Third Dose of DTP Containing Vaccine

Background: Comparison of target populations for immunization used by national immunization programmes with independent sources can be useful for identifying irregular patterns. Similarly, understanding differences in computed coverage levels that result from changes in target population estimates can be important. Methods: Using data reported annually by national immunization programmes to WHO and UNICEF, we compared the national number of births and surviving infants with estimates reported by the United Nations Population Division (UNPD). We also re-computed and compared coverage levels for the third dose of DTP containing vaccine (DTP3) using the nationally reported number of children vaccinated with DTP3 (the numerator) and the nationally reported number of children in the target population (the denominator) and compared this value with DTP3 coverage computed using the nationally reported number of children vaccinated and the UNPD estimate of the national number of surviving infants as an independent denominator. Results: We observed differences in the number of births and surviving infants reported by national immunization programmes compared with those estimated by the UNPD. Year-to-year changes in the number of births and surviving infants reported by national immunization programmes often exceeded those estimated by the UNPD. The re-computed administrative coverage levels for DTP3 using a nationally reported target population tended to be higher on average than those re-computed using the UNPD target population estimates. Conclusion: Target population estimates are a challenge for immunization programmes, and comparison to independent sources can be useful. There is increasing need to trace and better understand the processes and conditions affecting the enumeration and recording of the number of children in the target population for immunization services and the number of children vaccinated while recognizing that the challenge to do so is greater in some locations than others.

利用LQAS方法开展疫苗接种率调查的分析

目的：比较厦门市儿童调查疫苗接种率与常规免疫报告接种率的差异，评价调查抽样方法LQAS的优点与缺点。方法采用批质量保证抽样方法（ LQAS）抽取厦门3个乡镇适龄儿童各42名，调查统计儿童疫苗接种情况，并将调查疫苗接种率与中国国家常规免疫监测系统中报告疫苗接种率进行比较。结果3个街道/乡镇调查疫苗接种率均在97.62%以上，报告疫苗接种率均在97.84%以上。思明区鼓浪屿街道与湖里区金山街道调查疫苗接种率与报告疫苗接种率相比无显著性差异，而同安区西柯镇调查疫苗接种率低于报告疫苗接种率。结论 LAQS方法具有快速及便捷优点，适用于大规模接种率调查，并可评价报告接种率质量；但其不能精确估计接种率高低，在解决实际问题的调查中要慎用。在应用时要做好抽样的随机性及调查的质量控制。

Comparison of Cost Incurred in Two Survey Methodologies for Measles Vaccine Coverage

Background: The World Health Organization (WHO) initiated the Expanded Program on Immunization (EPI) in 1974. It has been widely used in different studies. Along with this, other survey methodologies have been compared to study immunization coverage at different regions. To consider different survey methodologies, one of the most important factors is the cost incurred that survey methodology. A survey method is considered as more efficient or better than the other survey method if the cost incurred in a particular method is less than the other one. Methods: In this study, cost incurred in two stage (30 × 30) cluster sampling and systematic sampling methods have been compared using a cost function for measles vaccine coverage. Measles vaccine coverage data has been taken from the survey “Comparison of Two Survey Methodologies to Estimates Total Vaccination Coverage” sponsored by Indian Council of Medical Research (ICMR), New Delhi. Results: The results show that there are no significant differences between the point estimates of measles vaccine coverage under the considered survey methodologies. But the cost incurred in systematic sampling is more than that of two stage cluster sampling. Conclusion: It can be concluded that systematic sampling survey is costlier than that of two stage cluster sampling for this study population.

Survey of coverage,strategy and cost of hepatitis B vaccination in rural and urban areas of China

AIM In order to understand the coverage, immunization strategy and cost of hepatitis B (HB) vaccination of China in recent years. METHODS A two stage household random sampling method was used in the survey. RESULTS The survey carried out at 112 Disease Surveillance Points (DSPs) of 25 provinces, autonomous regions and municipalities of China in 1996, showed that the coverage rates of HB vaccination among neonates were 96 9% in the urban DSPs and 50 8% in the rural DSPs in 1993-1994, while in students aged 7-9 years, they were 85 8% and 31 5% in 1994, respectively. Up to 1994, 97 5% of the urban DSPs and 73 9% of the rural DSPs on a neonate vaccination against HB program were included in EPI. About 93% of the urban DSPs and 44% of the rural DSPs did HBsAg and HBeAg screening for all or part of pregnant women. The neonates received the regimen of high dose HB vaccine in combination with hepatitis B immune globin (HBIG) if their mothers were HBsAg and/or HBeAg positive in pregnancy, otherwise they received the low dose vaccine (10μg×3). Part of DSPs had a lower neonate coverage due to unreasonable allocation of the vaccines (used for adults not at risk) or higher cost or insufficient supply of the vaccines. It is necessary to evaluate the quality of serological lab test to HBVMs in the maternal prescreening. CONCLUSION Remarkable achievements have been made according to the national planning and policy of HB immunization in China.

Vaccination Coverage and Its Determinants in Children Aged 11 - 23 Months in an Urban District of Nigeria

Background/Objectives: Performance of the vaccination programme in Nigeria is lower than the regional average as well the 95% target necessary for sustained control of vaccine preventable diseases. This study is aimed at assessing the vaccination coverage and its associated factors in children aged 11 - 23 months in Enugu Metropolis. Methods: A cross sectional study in which caregivers and their children pair, aged 11 - 23 months attending children’s outpatient clinics in Enugu metropolis was undertaken. Respondents were selected consecutively while data were collected using pretested interviewer administered semi-structured questionnaire. Data were analyzed using SPSS version 20.0 while level of significance was set at p < 0.05. Logistic regression analysis was used to identify independent predictors of full vaccination. Results: Of 351 subjects studied, 84.9% (298) were fully immunized according to the national programme on immunization schedule using both vaccination cards and history. The OPV0, OPV3, pentavalent-1, pentavalent-3 and measles coverage at the time of survey were 100.0%, 97.2%, 98.0%, 98.6%, 96.9% and 95.4%, respectively. On logistic regression: maternal occupation (government employees), children born in government hospitals and knowledge of when to start and complete vaccinations in a child were the likely predictors for completion of full vaccination in the children. Conclusion: The vaccination coverage among the study group was adjudged to be relatively high. Delivery of a child in a government hospital and the knowledge of the age when routine vaccinations should begin and end in a child were the independent predictors of the high vaccination coverage rate observed. Awareness and health education efforts in government tertiary hospitals should be extended to private and other hospitals to improve and sustain national vaccination coverage in Nigeria.

Proportionate Target Population Estimates Used by National Immunization Programmes in Sub-Saharan Africa and Comparison with Values from an External Source

Background: In order to effectively plan the delivery of immunization services, manage stock and supply levels and target interventions, national immunization programmes (NIP) must have an estimate of the target population they serve. To overcome challenges with target population estimation, some NIPs apply “rule-of-thumb” conversion factors to total population estimates. We compare these proportionate target population values with those from an external source. Methods: Using data reported by national immunization programmes in sub-Saharan Africa, we computed the proportionate target population as the number of births, surviving infants and children under 5 years of age, respectively, as a proportion of the total population size. We compared these values with those estimates computed from United Nations Population Division (UNPD) data. We then recomputed NIP target population sizes using the proportionate target population values from the UNPD applied to the total population size reported by NIP. Results: Data were available from 47 sub-Saharan Africa countries. Births as a proportion of the total population were greater within reports from NIP (median, 0.0400;IQR: 0.350 - 0.0437) compared to values from UNPD estimates (median, 0.0364;IQR: 0.0332 - 0.0406). Similar patterns were observed for surviving infants (median: NIP, 0.0360;UNPD, 0.0337) and children under 5 years of age (median: NIP, 0.1735;UNPD, 0.1594). The percent difference in proportionate target population ratios between reports from NIPs and the UNPD was >10% in 23 countries for births, in 18 countries for surviving infants, in 15 countries for children under 5 years of age. After re-computing target populations using UNPD proportionate target population values applied to NIP reported total population, recomputed administrative coverage levels for the third dose of DTP containing vaccine were higher in 32 of the 47 countries compared to reported administrative coverage levels. Conclusion: Because childhood immunization-related target populations are among the more difficult ones to accurately estimate and project, immunization programmes in sub-Saharan Africa are encouraged to include a critical assessment of the target population values, in conjunction with their national statistics system, as part of the on-going programme monitoring process.

Impact of Hepatits B Vaccination as an Important Indicator for Immunization Program in Albania

Albania has been a country with a high prevalence of hepatitis B virus. Hepatitis B vaccine has been introduced nationwide in Albanian Immunization Program in 1994. Hepatitis B is given at birth, as a separate antigen, followed by three doses at 2, 4 and 6 months, where Hepatitis B, starting from 2009, is part of pentavalent vaccine of DTP-HepB-Hib. The aim of this study was to evaluate Immunization Program with Hepatitis B vaccination in order to prove program efficacy, increase public confidence in immunizations and advocate for sustainable immunization programs. Methodology was based on three components such as Immunization coverage surveys, serologic surveys and surveillance for acute cases of Hepatitis B. Results of this study showed that vaccination coverage is really high, more than 95% all over the country and with drop-out rates less than 10%. Anti-HBs levels in immunized children were very high in comparison with unimmunized ones. Incidence of HBV in children 0-14 years old is almost zero. Such results tell us that Hepatitis B vaccination is one of the most fruitful strategies for long term control of Hepatitis B disease.

北京市3岁前儿童非免疫规划疫苗接种状况与趋势研究

目的了解北京市3岁前儿童非免疫规划(non-expanded programme on immunization,non-EPI)疫苗接种水平和变化趋势,为加强对非EPI疫苗管理提供参考。方法2023年9月1日,采用系统抽样方法随机抽取北京市免疫规划信息管理系统中2011、2014、2017和2020年的8月份出生的所有儿童个案,分析各年份抽样儿童3岁前接种非EPI疫苗的种类及户籍分布、首剂接种比例、全程免疫完成比例及其变化趋势。结果研究对象共108210名。非EPI疫苗总剂次分别为88019、109442、104451和130501剂次。研究对象3岁前水痘疫苗、肠道病毒71型灭活疫苗(EV71疫苗)和吸附无细胞百白破灭活脊髓灰质炎和b型流感嗜血杆菌(结合)联合疫苗(DTaP-IPV-Hib五联疫苗)首剂接种比例均逐年增加,由最初的<10%分别增加至82.20%、61.07%和39.20%;2020年研究对象中,接种总剂次居前5位的非免疫规划疫苗是13价肺炎疫苗、DTaP-IPV-Hib五联疫苗、EV71疫苗、5价轮状病毒疫苗和水痘疫苗,首剂接种比例分别为48.30%、39.20%、61.07%、30.58%和82.20%,京籍儿童均高于非京籍儿童(P<0.05);3岁前DTaP-IPV-Hib五联疫苗、EV71疫苗和5价轮状病毒疫苗在接种首剂后的多剂次疫苗的全程免疫完成比例分别为92.26%、96.56%和94.37%,京籍儿童均高于非京籍儿童(P<0.05)。结论北京市3岁前儿童非EPI疫苗接种数量和新疫苗种类不断增加,全程接种依从性较高。而在非EPI疫苗的首剂接种比例和非京籍儿童中均需进一步提高。建议开展相关影响因素研究,加强非免疫规划疫苗的技术指导,进一步提高全市非免疫规划疫苗接种数量和质量。

2020年云南省儿童免疫规划疫苗接种率调查

目的了解2020年云南省NIP疫苗接种情况,进一步巩固和提高接种率。方法在全省范围内随机抽取43个乡镇,入户调查2016年1月1日-2017年9月1日出生的儿童的NIP苗接种情况,并按全省和州市水平评价接种率。结果共调查1773名儿童,建证率为100%。在20剂次NIP疫苗中,除PV4外,其余19剂次疫苗的接种率均大于90%。16个州(市)PV4、DTP4、MenA2、JE2疫苗的接种率均低于90%。相较2015年,JE2、HepA、MenA+C1疫苗的接种率明显提高。结论云南省NIP疫苗接种率总体保持较高水平,但不同州(市)仍存在差异。2020年全省免疫规划工作相较2015年有稳步进展,但仍需加强薄弱地区和低接种率疫苗的预防接种服务管理工作,进一步提高NIP疫苗接种率。

Advancing the National Immunization Program in an era of achieving universal vaccine coverage in China and beyond

Background Immunization is a cornerstone of public health.Despite great success,China’s National Immunization Program(NIP)faces challenges,such as the integration of several World Health Organization-recommended vaccines and other systemic issues.The Innovation Laboratory for Vaccine Delivery Research(VaxLab),supported by the Bill&Melinda Gates Foundation and established in 2021 at Duke Kunshan University,focuses on enhancing China’s NIP through research and policy advocacy.This editorial aims to summarize the key findings of the manuscripts published in the collection contributed by VaxLab team and set the future research agenda.Key findings The collection contains eleven manuscripts discussing China’s immunization landscape and strategies to improve coverage,particularly for non-NIP vaccines like human papillomavirus vaccine(HPV),pneumococcal conjugate vaccine(PCV),Haemophilus influenzae type b vaccine(Hib),and rotavirus vaccines.Key findings include:(i)The COVID-19 vaccination campaign demonstrated China’s capacity for rapid,large-scale immunization efforts,suggesting potential for broader vaccine coverage improvements;(ii)Efforts in combating cervical cancer through the HPV vaccine indicate progress but also highlight challenges like vaccine supply and equitable access;(iii)The lag in adopting higher-valent paediatric combination vaccines in China needs attention to address regulatory and health system hurdles;(iv)Disparities in access to non-NIP vaccines underscore the need for government initiatives to improve vaccine coverage,especially for remote areas and marginalized populations;(v)Original studies emphasize the influence of caregivers’knowledge,health workers’financial incentives,and concerns about vaccine efficacy on immunization rates;(vi)Case studies from the Weifang City of China and Indonesia to introduce PCV offer insights on successful vaccine introduction strategies and the impact of innovative financing and government support.Conclusion The articles emphasize the need for government leadership,strategic policymaking,and public awareness to enhance vaccine coverage and equity.The VaxLab will continue strengthening China’s NIP by focusing on vaccine financing,emphasizing diversity,equity,and inclusion,and improving maternal vaccination coverage.Research will extend to Southeast Asian and Western Pacific regions,especially in middle-income countries facing challenges in vaccine financing and delivery.The collective efforts outlined in this collection show a commitment to evolving and adapting immunization strategies to meet global health goals and to provide equitable access to vaccines for all.

个体随机模型驱动的疫苗直接和间接效果评估

[目的]丰富国内疫苗效果评估策略,为制定免疫计划或筛选/候选疫苗提供科学依据.[方法]采用基于人群均匀混合假设的个体随机模型,以新型冠状病毒Omicron变异株为例,考虑疾病自然史、人群接触度、疫苗覆盖率和效果等因素,将个体层面疫苗的防感染和防传播效果推及群体层面的直接和间接效果.[结果]模拟结果分4个场景讨论仅提升疫苗覆盖率(vaccine coverage,VC)或仅提升疫苗效果(vaccine effectiveness,VE)的结局指标.当VE分别为0.5和0.9时,将VC从50%提升至90%,受间接效果保护人群的日新增感染率峰值的降幅分别为31.1%和72.1%,大于仅提升VE的场景;但仅提升VE的场景的直接效果不论在累积感染率还是日新增感染率指标上,均优于仅提升VC的场景.疫苗混合效果受直接效果影响较大;要实现10%以上的间接效果,至少需要接种覆盖90%以上的易感者,且疫苗防传播和防感染效果均超过85%,或其中一者接近90%,另一者接近80%.[结论]上述结果表明提升VE相比于提升VC在群体层面上更具有公共卫生学意义.但当前的新型冠状病毒疫苗防感染和防传播效果均不理想,因此加强个体接种来提升VC仍具有重要意义.间接效果随着VC的增加而增加,这将为群体中无法接种的个体提供一定保护作用.

不同成人乙肝疫苗接种程度对免疫效果的影响观察

目的观察不同成人乙肝疫苗接种程度对免疫效果的影响。方法从2021年3月—2022年4月在某医院注射成人乙肝疫苗服务对象中,抽取120例作为研究样本,以免疫注射程序为分组依据,将所有患者平均分为研究组和对照组,研究组接受0-1-6程序接种,对照组接受0-1-3程序接种,每组60例。120例患者接种的疫苗均为重组酵母乙肝疫苗,注射剂量是20μg,分别评价完成免疫注射后1个月、6个月、12个月的效果,同时记录不良反应发生情况。结果完成免疫注射后的1个月时,两组患者在抗-HBs、抗-HBc阳性率上的差异无统计学意义(P>0.05);免疫注射6个月、12个月时,研究组的抗-HBs与抗HBc阳性率均高于对照组,组间差异有统计学意义(P<0.05);两组患者均没有不良反应发生。结论注射乙肝疫苗时,采取0-1-6免疫注射程序的效果更佳,安全性能够得到更好保障,具有极高推广应用价值。