儿童疫苗接种家长态度问卷(PACV)的汉化和信效度研究

目的 将儿童疫苗接种家长态度问卷（Parent Attitudes about Childhood Vaccines，PACV）翻译成中文并测量其信效度。方法 采用跨文化调适指南提出的翻译步骤，对PACV进行翻译、整合、回译、文化调适，将翻译好的问卷完成预试验后，对148例6岁及以下的患儿家长进行调查。结果 量表一共包含15个条目，内容效度指数为1.0。因子分析显示Bartlett球形检验KMO值为0.702（P<0.01），主成分分析提取出3个因子，累计方差贡献率56.1%。3个因子分别归纳为"总的态度和信任度"、"对疫苗安全性和有效性的信念"和"免疫接种行为"，且均与原量表吻合。量表总的Cronbach's α值为0.701，分量表"总的态度和信任度"、"安全性和有效性"、"疫苗接种行为"的信度分别为0.810、0.704和0.604。2周后重测信度总量表为0.753，分量表分别为0.798、0.714和0.701。结论 中文版PACV具有良好信效度，但鉴于样本的单一性，尚需多中心、大样本的研究进一步验证。     

改进健康教育方式应用于社区流动儿童及时接种疫苗的效果观察

目的 探讨改进健康教育方式应用于社区流动儿童及时接种疫苗的效果。方法 将2021年1月—2022年7月期间于南平市第一医院崇阳街道社区卫生服务中心（原云谷门诊部）接种的121名流动儿童作为研究对象,按照随机数字表法分为2组,对照组（60名）给予常规健康教育,观察组（61名）给予改进健康教育,比较2组及时接种率,家长健康信念、知识知晓率。结果 观察组及时接种率为96.72%,高于对照组的83.33%(P<0.05)。干预前,2组家长健康知识、态度与信念、行动评分及健康信念总分对比,差异无统计学意义（P>0.05）;干预6个月后,观察组家长健康知识、态度与信念、行动评分及健康信念总分均较对照组高（P<0.05）。观察组家长知识总知晓率为95.08%,高于对照组的81.67%(P<0.05)。结论 改进健康教育方式应用于社区流动儿童疫苗接种中,可提高及时接种率,增强家长健康信念,提高家长对疫苗接种及相关知识的知晓率。     

健康教育对社区婴儿家长参与儿童保健的影响

目的：分析健康教育对社区婴儿家长参与儿童保健的影响。方法：选取2022年1—12月苏州市吴中区社区的150名婴儿家长作为研究对象,随机分为观察组与对照组,各75名。对照组采用常规社区干预,观察组给予健康教育。比较两组家长儿童保健知识评分及掌握情况、两组婴儿疫苗接种情况。结果：干预前,两组家长儿童保健知识评分比较,差异无统计学意义（P>0.05）;干预后,两组家长儿童保健知识评分均高于干预前,且观察组高于对照组,差异有统计学意义（P<0.05）。观察组家长儿童保健知识总掌握率高于对照组,差异有统计学意义（P=0.029）。观察组婴儿乙肝疫苗、脊髓灰质炎疫苗、百白破疫苗、麻疹腮腺炎风疹联合减毒活疫苗、流脑疫苗、轮状病毒疫苗接种率高于对照组,差异有统计学意义（P<0.05）。结论：健康教育可提高家属儿童保健知识掌握率,提高婴儿疫苗接种率,值得推广。     

儿童疫苗接种的不良反应及护理干预的效果

目的 分析儿童疫苗接种发生不良反应的原因,并探讨强化常规护理干预的效果.方法 选取2016年1～12月接受疫苗接种的1774名儿童为研究对象,采用随机数表法分为观察组和对照组,每组887名.对照组给予常规护理措施,观察组给予强化常规护理干预措施,比较两组儿童疫苗接种的不良反应发生情况,并调查家长的满意度.结果 1774名儿童接种疫苗后发生因接种疫苗导致不良反应的因素主要为儿童体质与状态,也不排除疫苗质量与接种时间的因素;接种疫苗后观察组的不良反应(一般反应+异常反应)发生率为0.79％,明显低于对照组的2.14％,差异有统计学意义(P<0.05);观察组儿童家长对医护人员的服务水平与态度的满意度为97.1％,高于对照组的90.5％,差异有统计学意义(P<0.05).结论 强化常规护理干预可显著降低儿童接受疫苗接种后的不良反应发生率,同时提高了儿童家长对医务人员的满意度.     

相城区0～6月龄儿童家长对非免疫规划疫苗的接种意愿及影响因素分析

目的：分析相城区0～6月龄儿童家长对非免疫规划疫苗的接种意愿及影响因素。方法：选取2019年1月—2021年12月在苏州市相城人民医院预防保健科首次建立预防接种证的2 200名0～6月龄儿童家长作为研究对象，对其进行问卷调查，收集基本资料、非免疫规划疫苗知识、接种意愿等资料，并进行相关分析。结果：本研究共回收问卷2 103份，有效问卷2 093份，有效回收率为99.52%。家长文化程度、儿童户籍地、是否知晓非免疫规划疫苗、是否知晓非免疫规划疫苗和免疫规划疫苗的区别、是否有必要接种非免疫规划疫苗、接种非免疫规划疫苗是否安全、对非免疫规划疫苗价格接受程度是0～6月龄儿童家长非免疫规划疫苗接种意愿的影响因素，差异有统计学意义(P<0.05)。知晓非免疫规划疫苗，认为完全有必要、部分有必要、没想好是否要接种非免疫规划疫苗，认为接种非免疫规划疫苗安全，对非免疫规划疫苗价格接受程度在200～499元、500～999元、≥1 000元是0～6月龄儿童家长非免疫规划疫苗接种意愿的独立影响因素(P<0.05)。结论：0～6月龄儿童家长对非免疫规划疫苗的接种意愿较高，对非免疫规划疫苗的认知和接...     

儿童家长对疫苗接种及不良反应的知识、态度、行为调查

目的：调查儿童家长对疫苗接种及不良反应的知识、态度、行为。方法：该院于2015年1月至2015年12月期间对124例儿童进行疫苗接种,自制问卷,对所有儿童家长进行调查,统计儿童家长对疫苗接种的认识。结果：124例家长中,有104例认为儿童接种疫苗后出现轻微的反应是正常情况;28例儿童接种疫苗后出现了不良反应。结论：儿童家长对疫苗接种及不良反应有一定的认识,但是认识不深刻,仍然存在偏差,所以医护人员必须要加强疫苗接种宣传教育,提高家长的认知水平,纠正家长错误的行为,为儿童的健康提供保障。     

广州市家长对未成年子女接种季节性流感疫苗的风险认知及态度研究

目的 了解广州市家长对未成年子女接种季节性流感疫苗的风险认知及态度.方法 通过连续取样方法对275名家长使用结构式儿童季节性流感疫苗调查访谈问卷进行研究.结果 (1)30.5％(84/275)的家庭子女接种了流感疫苗.(2)接种与未接种流感疫苗的家长对接种疫苗的风险认知差异无统计学意义(χ2=0.970、1.010、2.790、0.290、2.670、3.520,P>0.05).(3)接种与未接种流感疫苗的家长对流感疫苗有效性的认可态度、流感疫苗接种建议的接受态度、流感疫苗接种行为的否定态度等方面差异具有统计学意义(χ2=9.880、8.760、10.450、7.180、10.760、25.770、5.570、4.490,P<0.05).(4)未成年子女是否接种疫苗与家长年龄(χ2=4.680,P<0.05)、受教育程度(χ2=3.950,P<0.05)分布差异具有统计学意义.(5)未来1年未成年子女是否接种疫苗与家长获取疫苗信息途径种类(r=0.423,P<0.001)呈正相关.结论 广州市家长对未成年子女接种季节性流感疫苗的风险认知不足,子女是否接种疫苗受家长年龄、受教育程度影响,需加强流感疫苗接种的宣传.     

留守和非留守儿童监护人预防接种知识、态度、行为现状和知识需求情况调查

目的 探讨留守和非留守儿童监护人预防接种知识、态度、行为现状和知识需求情况及针对性干预模式。 方法 选取64名于2016年12月至2018年12月体检的农村留守儿童（甲组）和同期体检的64名非留守儿童（乙组）,通过对儿童预防接种卡的查验了解儿童接种率的现状,同时通过问卷调查的方式了解儿童监护人对预防接种的知识、态度、行为现状和知识需求情况及针对性干预模式。 结果 在128名儿童中,有93名（72.65%）儿童接种完全程基础疫苗,其中留守儿童34名（63.56%）,非留守儿童59名（63.44%）,乙组儿童乙肝疫苗3次接种率、脊灰疫苗3次接种率、乙脑疫苗、百日破和A群流脑疫苗接种率均高于甲组（P < 0.05~P < 0.01）。所有儿童监护人均对问卷设计的相关预防接种知识具备较好的认识,其中乙组儿童的监护人在“知道出生需要接种哪两种疫苗”“知道预防接种的作用”“知道儿童何时开始要打疫苗”3个条目的正确认识率均高于甲组（P < 0.05）;2组儿童监护人对其他7条预防接种知识的正确认识率差异均无统计学意义（P>0.05）。5项疫苗接种行为及需求中,甲组儿童监护人“认为接种地点距离太远率”比例高于乙组（P < 0.01）,其余4项在2组儿童监护人之间差异均无统计学意义（P>0.05）。 结论 如何调动村级预防接种人员的积极性是针对留守儿童预防接种干预的工作重点,建议将同伴教育的宣传方式引进留守儿童家庭进行相应的宣传教育,从而加强对留守儿童预防接种工作的关心与投入。     

2个居民区0～7岁儿童计划免疫现状及影响因素分析

目的 探讨影响儿童免疫规划的因素.方法 抽取2个居民小区的1 205名0～7岁儿童,采用相关知识问卷及核查疫苗接种记录的方式,对入组儿童的疫苗接种情况、居住地变更情况、父母文化程度、家长对接种疫苗的态度以及家长免疫规划相关知识的掌握程度做详细调查.结果 2个小区0～7岁儿童计划免疫建卡率为93.61%;五苗的接种率分别为麻疹类疫苗96.38%、卡介苗96.33%、脊髓灰质炎疫苗95.87%、乙肝疫苗94.29%、百白破疫苗96.01%,"五苗"全程接种率为94.59%.结论 0～7岁儿童的计划免疫现状较好,但流动儿童与本区常住儿童相比疫苗接种率和"五苗"全程接种率均较低.所以,应加强流动儿童免疫规划的宣传教育工作,以减少相应传染病的发生率.     

海口市儿童计划免疫接种率及其影响因素分析

目的调查我市儿童计划免疫接种情况并分析其影响因素,以进一步提高儿童计划免疫接种率。方法按照人口比例在我市四区选取在2011年1月1日至2012年1月1日间出生的儿童300名。对其进行入户调查,查询儿童计划免疫接种情况及家庭基本情况,并对影响因素进行单因素和多因素Logistic回归分析。结果儿童计划基础免疫（卡介苗、脊髓灰质炎减毒活疫苗、麻疹疫苗、百白破混合制剂和乙肝疫苗）单苗或＂五苗＂接种率均在95%以上,加强型免疫（百白破,麻腮风）接种率和省级增加的国家免疫规划疫苗（流脑疫苗、甲肝疫苗）接种率分别为71.33%和63.67%。多因素Logistic回归分析显示,户口所在地、父母学历、各疫苗接种时间、家长对加强疫苗和省级增加疫苗态度是影响儿童计划免疫接种率的主要因素。结论海口市儿童计划基础免疫接种率较高,覆盖率较广,但是加强免疫接种和省级增加的国家免疫规划疫苗接种率较低,应针对其主要影响因素制定相应措施,提高加强型疫苗和省级增加的疫苗接种率。     

儿童家长预防接种知识知晓情况现状分析

目的了解儿童家长对预防接种知识的知晓情况,提高儿童免疫接种水平,促进儿童预防接种工作的开展。方法统一制定调查问卷,在预防接种门诊、幼儿园及公共场所对6周岁以下儿童家长发放调查问卷进行调查．对回收的480份调查表资料用Excel进行整理及统计分析。结果88．13％的家长全部或部分知晓本地区应接种的10种国家基础免疫疫苗和接种程序,家长知晓率较高的疫苗有乙肝疫苗、卡介苗、麻疹（麻风二联疫苗）、VI服脊灰糖丸（OPV）等;家长对基础疫苗可预防乙型肝炎、甲型肝炎、麻疹、脊髓灰质炎、结核病等相应传染病的知晓率较高：家长预防接种相关知识的主要来源90．83％是预防接种门诊医生告知,82．71％是预防接种门诊接种通知信息告知,75．83％是预防接种告知书获知;87．71％的家长会主动按照接种程序带孩子接种疫苗;影响家长预防接种知识和重视度的因素有家长文化程度、户籍等。结论应进一步加大预防接种的健康教育宣传工作力度。疾控机构主动加强宣传和服务行为,提高家长的自觉性与参与性,促进儿童预防接种工作的开展。     

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%.     

Trust versus concerns—how parents reason when they accept HPV vaccination for their young daughter

Abstract

Background. From spring of 2012, human papillomavirus (HPV) vaccine against cervical cancer is offered free of charge to all girls aged 10–12 years through a school-based vaccination programme in Sweden. The aim of this study was to explore how parents reason when they accept HPV vaccination for their young daughter and also their views on HPV-related information.

Methods. Individual interviews with parents (n = 27) of 11–12-year-old girls. The interviews were recorded, transcribed verbatim, and analysed using thematic content analysis.

Results. Three themes emerged through the analysis: Trust versus concern, Responsibility to protect against severe disease, and Information about HPV and HPV vaccination is important. The parents expressed trust in recommendations from authorities and thought it was convenient with school-based vaccination. They believed that cervical cancer was a severe disease and felt a responsibility to protect their daughter from it. Some had certain concerns regarding side effects and vaccine safety, and wished for a dialogue with the school nurse to bridge the information gaps.

Conclusions. Trust in the recommendations from authorities and a wish to protect their daughter from a severe disease outweighed concerns about side effects. A school-based vaccination programme is convenient for parents, and the school nurse has an important role in bridging information gaps. The findings from this qualitative study cannot be generalized; however, it can provide a better understanding of how parents might reason when they accept the HPV vaccination for their daughter.     

Epidemic of mumps in a partially immune population.

The incidence of mumps in vaccinated and nonvaccinated schoolchildren was studied after a recent epidemic. Information was collected by telephone interviews with the parents and a review of the physicians' records. The vaccine appeared to be effective, for the incidence of mumps in the 145 vaccinated children--5.5%, or 8 cases--was significantly less (P less than 0.001) than the incidence in the 350 children considered susceptible to infection--21.7%, or 76 cases. The percentage of children who had been immunized decreased with increasing age, and acquisition of immunity through natural infection had the reverse trend; thus, the proportions of children susceptible to infection in each age group were about the same, and the age-specific attack rates were similar. Although the mothers were accurate in indicating absence of vaccination, they incorrectly indicated vaccination of their children 43.0% of the time; this error in reporting could influence vaccine administration in older children. Our findings suggest that mumps vaccination may substitute for natural illness in immunizing populations, and that more extensive use of the vaccine over a broader age range is required to prevent similar epidemics in the future.     

Optimal age for measles and mumps vaccination in Australia

Trivalent measles-mumps-rubella vaccine has recently replaced measles-mumps vaccine in Australia and is recommended as a single dose at the age of 12 to 15 months, with the exception of Aboriginal children in central Australia who are vaccinated at 9 months. The timing of measles vaccination has been controversial not only in Australia but also in the United States, where measles outbreaks continue to occur. This study aimed to determine seroconversion rates for measles-mumps vaccine in children aged 12 to 18 months and to make a recommendation for the timing of vaccination based on seroconversion rates and attack rates. The parents of 425 children aged 12 to 18 months gave consent for their children to have serum collected at the time of measles-mumps vaccination and three months later. The mean age at vaccination of the children who had two serum samples for measles and mumps antibody estimations was 13.9 months (mode, 13.1). The seroconversion rate for measles was 95% (314/329) (95% confidence interval (CI), 92.5% to 97.3%) and for mumps 97% (309/320) (95% CI, 93.8% to 98.1%). There were no statistically significant differences in the rates of seroconversion for measles or mumps related to age in months at the time of vaccination or in post-vaccination measles antibody titres related to age at vaccination. Post-vaccination mumps antibody titres tended to be lower in older vaccinees. None of the children who presented for vaccination had serological evidence of prior measles infection but five had evidence suggestive of prior mumps. As the seroconversion rates for measles and mumps vaccines were very high in these children it was concluded that no advantage resulted from delaying vaccination until 15 months and that the current National Health and Medical Research Council recommendations for vaccination at age 12 to 15 months should remain.     

石家庄市大学生对HPV认知状况及疫苗接种意愿调查

目的采用不同模型对不同知识得分情况进行分析,研究石家庄市大学生对人乳头瘤病毒（human papilloma virus,HPV）疫苗的接种意愿及其影响因素,为向石家庄市大学生HPV疫苗的推广提供理论基础和依据。 方法采取随机抽样的方法,对石家庄市11所大学的大学生开展有关人口学、HPV及宫颈癌认知、性行为、HPV疫苗的认知和接种意愿的问卷调查,共收回1 622份有效问卷。采用卡方检验比较不同接种意愿的大学生在基本信息、性行为和感染自觉性上的差异,采用秩和检验比较不同接种意愿的大学生对HPV相关知识了解程度的差异,采用Logistic回归模型分析影响接种的因素。 结果45.62%（740/1 622）的大学生表示愿意接种HPV疫苗,而54.38%（882/1 622）表示不愿意接种HPV疫苗。愿意接种组和不愿意接种组的学生的HPV相关问题总得分分别为6.000（8.000）和1.000（7.250）,差异有统计学意义（P＜0.001）,将总得分划分为HPV及宫颈癌相关知识得分和HPV疫苗相关知识得分2个维度及多个小维度后差异仍有统计学意义（P＜0.001);Logistic回归分析的结果显示,HPV相关知识得分均与接种意愿有统计学关联（P＜0.001）,分数越高,接种意愿也会随之增高;模型1、2、3在均衡生活费、性别、籍贯等因素后,OR值下降,模型4 加入性行为和感染风险自觉性后,相较于模型3 ,OR值上升。 结论石家庄市大学生HPV疫苗接种的接受率低于全国水平,HPV疫苗接种率与相关知识有关,提高大学生HPV相关知识水平,会增加其对疫苗的接受率,故相关部门需加强宣传力度,增强大学生自我保护意识。     

Local reactions after the fourth dose of acellular pertussis vaccine in South Australia

OBJECTIVE: To assess the reported rate of local reactions after administration of acellular pertussis vaccine (DTPa) according to dose number and type of pertussis vaccine (whole-cell or acellular) used for the primary course, and to document the severity and outcome of fourth-dose local reactions. DESIGN AND SETTING: Retrospective review. Reports of adverse events after vaccination in South Australia between 1 January 1997 and 31 December 2000 were reviewed, and a questionnaire administered to all parents who reported a local reaction after the fourth dose of DTPa. MAIN OUTCOME MEASURES: The number, and rate per 100 000 administered doses, of local reactions following the primary and booster doses of DTPa, and of local reactions after the fourth-dose in cohorts of children whose primary vaccinations were with either DTPw or DTPa. Redness and/or swelling at the injection site as reported by parents. RESULTS: Of 581 reported adverse events after vaccination, 138 were local reactions after a pertussis-containing vaccine. Primary vaccinations with DTPa was a significant risk factor for a fourth-dose local reaction (relative risk, 6.7; 95% CI, 2.4-18.5). Parental questionnaires were completed for 45 of the 71 children (63%) with reported local reactions after the fourth dose of DTPa; extensive limb swelling was reported in 8 children (18%) and all except one child had recovered by the time of review. CONCLUSIONS: Parents should be informed that children receiving booster doses of DTPa vaccine, after primary doses with DTPa, are at increased risk of local reactions (which tend to resolve spontaneously) but not of systemic effects. Studies should be initiated to investigate the pathogenesis and the risk of recurrence of local reactions to further improve vaccination schedules.     

Survey of parents' attitudes to the recommended Haemophilus influenzae type b vaccine program.

A survey was conducted in a general pediatric practice to determine parents' attitudes to and compliance with the recommended Haemophilus influenzae type b vaccine program. Of 133 families surveyed 127 (95%) responded to the questionnaire. About one third of the parents did not have their children vaccinated. The decision against vaccination was made despite parent education, follow-up telephone contact and the pediatrician's expressed support of the vaccine program. Most of the respondents (86%) had no previous knowledge of the vaccine. The factor of greatest concern was the possibility of an adverse reaction. This concern was significantly more common among the parents who decided not to have their children vaccinated than among those who had their children vaccinated (chi 2 = 6.52, p less than 0.025). One third of the parents who indicated that they intended to have their children vaccinated required a telephone reminder. The findings suggest a need for public education about the vaccine, with particular emphasis directed at allaying fears about side effects.     

Anxiety and depression in an older research population and their impact on clinical outcomes in a randomised controlled trial

Introduction: Anxiety and depression are common in older people living in the community. The aim of the study was to investigate their impact on clinical outcomes during a randomised controlled trial investigating the cost benefits of influenza vaccination in fit and healthy, independent living 65–74 year olds. Subjects and methods: A total of 729 people were recruited. Participants completed the hospital anxiety and depression scale (HADS) and EuroQol EQ-5D quality of life questionnaire immediately before receiving vaccination and every two months for the next six months after this. Side effects three days after vaccination and Barthel score at baseline were also recorded. Results: At baseline the prevalence of "definite" anxiety in this sample (HADS score ≥11) was 4% and 1.2% of individuals had definite depression (HADS score ≥11). Individuals with anxiety or depression (HADS score ≥8) were more likely to complain of systemic side effects after vaccination and have a lower Barthel index score (p<0.001). Quality of life as measured by the EQ-5D visual analogue scale was reduced (p<0.001) at all time periods in those individuals with both anxiety and depression (HADS score ≥8 on both scales). Conclusion: Although the prevalence of anxiety and depression in this sample was low, people with anxiety or depression were more likely to suffer from perceived side effects after influenza vaccine and have a lower Barthel and EQ-5D visual analogue score. In future studies the effect of anxiety and depression on older participants should be remembered and care taken to ensure that they do not affect results more than the intervention under study.     

Outbreak of measles in a highly vaccinated secondary school population.

OBJECTIVE: To examine the factors associated with measles vaccine effectiveness and the effect of two doses of vaccine on measles susceptibility during an outbreak. DESIGN: Retrospective cohort study. SETTING: A secondary school in the City of Toronto. SUBJECTS: The entire school population (1135 students 14 to 21 years of age). MAIN OUTCOME MEASURES: Risk of measles during an outbreak associated with age at first measles vaccination, length of time since vaccination, vaccination before 1980 and whether date of vaccination was estimated; vaccine efficacy of one dose versus two doses. RESULTS: Eighty-seven laboratory-confirmed or clinically confirmed cases of measles were identified (for an attack rate of 7.7%). The measles vaccination rate was 94.2%, and 10% of the students had received two doses of measles vaccine before the outbreak. Among those who had received only one dose of vaccine, vaccination at less than 15 months of age was associated with vaccine failure (relative risk 3.62, 95% confidence interval 2.32 to 5.66). There was no increased risk of vaccine failure associated with length of time since vaccination once the relative risk was adjusted for age at vaccination in a stratified analysis. Vaccination before 1980 and an estimated date of vaccination were not associated with increased risk of vaccine failure. Administration of a second dose of vaccine during the outbreak was not protective. Two doses of vaccine given before the outbreak conferred significant protection, and the relative risk of failure after one dose versus two doses was 5.0 (95% confidence interval 1.25 to 20.15). Of the 87 cases, 76 (87%) could have been prevented had all the students received two doses of measles vaccine before the outbreak, with the first at 12 months of age or later. CONCLUSIONS: Delayed primary measles vaccination (at 15 months of age or later) significantly reduced measles risk at later ages. However, revising the timing of the current 12-month dose would leave children vulnerable during a period in which there is increased risk of complications. The findings support a population-based two-dose measles vaccination strategy for optimal measles control and eventual disease elimination.