Low mortality after mild measles infection compared to uninfected children in rural West Africa

BACKGROUND: It has been assumed that measles infection may be associated with persistent immune suppression and long-term excess mortality. However, few community studies of mortality after measles infection have been carried out. We examined long-term mortality for measles cases, sub-clinical measles cases, and uninfected contacts after an epidemic in rural Senegal. METHODS: The study was carried out in Niakhar, a rural area of Senegal. Index cases of measles were identified and children less than 7 years of age exposed to measles in the same compound had acute and convalescent blood samples collected. Clinically diagnosed measles cases were serologically confirmed. Children without clinical symptoms were classified as sub-clinical cases if they had a four-fold or greater change in antibody levels between samples collected at exposure and 1 month later and as uninfected if there was no or a two-fold change in antibody levels. RESULTS: There were 31 index cases, and among 184 exposed contacts, 35 (19%) children developed clinical measles. Among contacts that did not develop clinical measles, 45% had sub-clinical infection. Measles cases, sub-clinical cases, and uninfected contacts did not differ with respect to nutritional status. However, uninfected children without clinical symptoms and change in antibody level had higher initial measles specific IgG antibody levels and less intensive exposure to the index case. No index or secondary case of measles died in the acute phase of infection nor did any of the children exposed to measles die in the first 2 months after exposure. Exposed children developing clinical measles had lower age-adjusted mortality over the next 4 years than exposed children who did not develop clinical measles (P<0.05). Sub-clinical measles cases tended to have low mortality and compared with uninfected children, exposed children with clinical or sub-clinical measles had lower age-adjusted mortality (mortality ratio (MR)=0.20 (0.06-0.74)). Controlling for background factors had no impact of the estimates. CONCLUSIONS: When measles infection is mild, clinical measles has no long-term excess mortality and may be associated with better overall survival than no clinical measles infection. Sub-clinical measles is common among immunised children and is not associated with excess mortality.     

Routine vaccinations associated with divergent effects on female and male mortality at the paediatric ward in Bissau, Guinea-Bissau

Several studies have suggested that routine childhood immunisations may have non-specific effects on mortality. To examine which disease categories might be affected, we investigated whether immunisation status had an impact on the case fatality for hospitalised children. Between 1990 and 1996, the Bandim Health Project maintained a register of all children from the study area hospitalised at the paediatric ward of the central hospital in Bissau, Guinea-Bissau. The study included 2079 hospitalised children aged 1.5-17 months coming from the Bandim study area. Among children whose vaccination card had been seen at admission, the case fatality ratio for measles-vaccinated children versus measles-unvaccinated children was 0.51 (0.27-0.98), the beneficial effect being significantly stronger for girls than for boys (test of interaction, p=0.050). The protective effect of measles vaccine remained unchanged when hospitalised measles cases were excluded from the analysis (0.49 (0.26-0.94)). The effect of measles vaccine was strongest for children with pneumonia (MR=0.28 (0.07-0.91)) and presumptive malaria (MR=0.40 (0.13-1.18)). For measles-vaccinated children, the female to male case fatality ratio was 0.54 (0.28-0.97). Among children having received diphtheria-tetanus-pertussis (DTP) and oral polio (OPV) as the last vaccines, girls had higher case fatality than boys, the mortality ratio being 1.63 (1.03-2.59). The female to male ratios were significantly inversed for DTP and OPV versus measles vaccine (test of interaction, p=0.003). These results remained unchanged if 1-month post-discharge deaths were included in the analysis, and in multivariate analyses controlling for determinants of mortality. In conclusion, measles vaccine was associated with reduced mortality from diseases other than measles, the beneficial effect being stronger for girls than for boys. On the other hand, DTP and OPV vaccine were associated with higher case fatality for girls than for boys. Understanding the divergent non-specific effects of common vaccines may contribute to better child survival in developing countries.     

The survival benefit of measles immunization may not be explained entirely by the prevention of measles disease: a community study from rural Bangladesh

OBJECTIVE: To examine whether the reduction in childhood mortality after immunization can be explained by the prevention of measles and its long-term effects. METHODS: and Data We re-analysed an existing data set from Matlab, Bangladesh. During 1982-1985, measles immunization was used from 9 months of age in half of the study area, and the other half was used as an unvaccinated control area. A total of 8134 immunized children had been matched by age with 8134 non-immunized children; 578 children died during the follow-up period of 3 years. Using these data, we calculated the vaccine effectiveness against death (VED) controlling for significant factors in a matched analysis. In the absence of measles, there should be no difference in mortality between immunized, uninfected children and non-immunized, uninfected children. We therefore calculated VED after the exclusion of all measles cases in the survival analysis. To assess the long-term effects of measles, we compared survival of unvaccinated children after measles disease with children who had not yet contracted measles. RESULTS: Prior to immunization and again after 1985, childhood mortality rates were 10% lower in the area that had received immunization. Though measles deaths only constituted 12.4% of the non-accidental deaths, the VED controlling for significant factors was 49% (95% CI: 38-58%). The vaccine was protective against measles death throughout the study, but it also had a marked effect against other causes of death, particularly diarrhoea and oedema. This effect may have been particularly strong in the first 6 months after immunization (VED = 74, 95% CI: 57-84%). The VED was only reduced from 49% to 43% (95% CI: 31-54%) when measles cases were excluded in the survival analysis. Controlling for background factors, mortality among measles cases was increased during the acute phase (0-45 days) (mortality ratio [MR] = 17.35, 95% CI: 11.9-25.3) and in the following 1(1/2) months (MR = 2.35, 95% CI: 0.95-5.84). However, post-measles cases had significantly lower mortality than uninfected, non-immunized children in the following 9 months (MR = 0.40, 95% CI: 0.16, 0.98). CONCLUSIONS: The non-randomized character of the original study and the possibility of uncontrolled confounding between the two areas prevent a precise estimate of the effectiveness of measles vaccine, but it is likely to have been substantial. Though there may have been some underreporting of cases of measles, the prevention of measles infection can only explain a limited part of the observed impact of measles immunization in Bangladesh. Furthermore, mortality may be reduced after the acute phase of measles infection. The observations from Bangladesh are consistent with recent research from Africa suggesting that measles immunization may have non-specific beneficial effects on survival.     

Patterns of exposure and severity of measles infection. Copenhagen 1915-1925.

Using data on children hospitalized with measles in Copenhagen from 1915 to 1925, I found that secondary cases (infected at home) exposed to two or more index cases had a higher case fatality rate than did children exposed to a single index case (relative risk (RR) = 1.90; 95% confidence interval (CI): 1.12 to 3.22). Compared with surviving cases, fatal secondary cases had a shorter interval between their own rashes and rash in the index case (P < .02), suggesting a shorter period of incubation for severe cases. Secondary cases infected by a severe case of measles had higher mortality (RR = 3.87; 95% CI: 1.65 to 9.08) than did secondary cases infected by an index case without pneumonia. These observations suggest that differences in patterns of exposure, possibly due to the dose of infection, may be important for understanding variation in measles mortality.     

Severity of measles and cross-sex transmission of infection in Copenhagen 1915-1925

Using data on children hospitalized with measles in Copenhagen in 1915-1925, it was found that secondary cases infected at home by someone of the opposite sex had a relative case-fatality rate risk (RR) of 1.52 (95%, confidence interval (Cl): 0.80-2.88) compared with secondary cases infected by someone of the same sex. Males infected by a girl suffered more severely than when infected by another boy (RR = 2.46; 95% Cl: 1.00-6.04) whereas there was no difference for girls. In households with two cases of measles, case fatality was significantly higher in families with a boy and a girl infected at the same time compared with families with two boys or two girls (RR = 1.89; 95% Cl: 1.06-3.37). There was no difference in mortality in families with two boys or two girls having measles at the same time. These results strengthen previous observations from Guinea-Bissau that close contact with a child of the opposite sex increases the severity of measles infection.     

Oral polio vaccination and low case fatality at the paediatric ward in Bissau, Guinea-Bissau

Oral polio vaccine (OPV) and diphtheria-tetanus-pertussis (DTP) vaccines are given simultaneously in routine immunisation programmes in developing countries. It is therefore difficult to determine the separate effects of these vaccines on survival. We used the shortage of DTP vaccine in Bissau to examine the impact of OPV on the case fatality at the paediatric ward in Bissau. For 719 children less than 5 years of age whose vaccination card had been seen at admission and who had not yet received measles vaccine, having received OPV only was associated with a case fatality of 6% compared with 15% for children having received combined DTP and OPV vaccinations, the case fatality ratio (CFR) being 0.29 (95% confidence interval (CI) 0.11-0.77). Even if children fleeing the hospital were assumed to have died shortly after leaving the hospital, the case fatality would still be lower for children having received OPV only (CFR = 0.41; (95% CI 0.20-0.81)). The tendency was similar for children hospitalised with pneumonia, diarrhoea, and presumptive malaria. Control for background factors had no impact on the estimate. In areas with high mortality, OPV administered alone may have non-specific beneficial effects or DTP may have a negative effect for children who had received both DTP and OPV.     

Measles epidemiology and outbreak response immunization in a rural community in Peru.

Only limited data are available on the impact of measles outbreak response immunization (ORI) in developing countries. We conducted a community survey in Espindola, a rural border community in northern Peru, following a measles outbreak and subsequent ORI to study the epidemiology and impact of the outbreak and to evaluate the costs and benefits of measles ORI. During the outbreak, 150 of the 553 Espindola residents developed clinical cases of measles. Adults accounted for 44.0% of cases, and were frequently identified as primary cases. The attack rate among all susceptible people was 45.5% and was highest (61.2%) for the 16-20 year age group. Among adults, significant risk factors for developing measles included being aged 16-20 years (relative risk [RR] = 3.06, 95% CI = 2.08, 4.49) and being male (RR = 1.73, 95% CI = 1.11, 2.71). Among serologically confirmed cases, 60.7% developed diarrhoea and 32.1% pneumonia. The overall case-fatality rate was 3.3%, but reached 19.1% in the 0-23-month age group. Failure to reach children through either routine immunization or national campaigns made this community vulnerable to the severe and extensive impact of measles virus importation. The ORI campaign targeted non-measles case children aged 6 months to 15 years, regardless of their previous immunization status, and was effective in terminating this measles outbreak and in preventing morbidity, loss of livelihood and death despite the involvement of large numbers of adults in measles transmission. The last measles case occurred within 3 weeks of completing ORI. The ORI campaign, which would have cost approximately US$ 3000 in 1998, saved as many as 1155 person-days of work among 77 adults, prevented an estimated 87 cases of diarrhoea and 46 cases of pneumonia, and averted 5 deaths.     

Une enqu��te d'efficacit�� vaccinale dans la ville de Bongor (Tchad) et ses cons��quences op��rationnelles pour le programme de vaccination.

A measles epidemic occurred in the city of Bongor, Chad, from 22 September 1993 to 26 June 1994. A total of 792 patients were hospitalized, with a case fatality rate of 5.2%. After the epidemic, the district management team evaluated the expanded programme on immunization (EPI). Through a cluster survey the attack rate was estimated to be 29.1% (95% confidence interval (CI) = 20.4-37.8%) for the age group 12-59 months (n = 206). For this same age group, the measles immunization coverage was estimated to be 44.2% (95% CI = 34.6-53.8%) and the vaccine efficacy 9.5% (95% CI = 0-41.5%). Several flaws in the logistic handling of the vaccines and especially in the cold chain were identified. These results indicated a serious management problem in the EPI, which the district team then immediately started to rectify. The method used to estimate the immunization coverage and efficacy in the study is rapid and low cost. Also, it is feasible at the district level and permits identification of management problems in the EPI.     

Outbreak of adenoviral infections in a long-term paediatric facility, New Jersey, 1986/87.

During an 8-week period in the winter of 1986-87, there were 11 deaths from an adenovirus infection (case fatality rate = 39%, 11/28) in a long-term care paediatric facility in southern New Jersey. Among the 61 resident children, all with severe congenital and/or acquired disabilities, 28 developed a febrile respiratory illness compatible with adenovirus infection [attack rate (AR) = 46%]. Patients with tracheostomies were three times as likely to become ill [relative risk (RR) = 3.2, 95% confidence intervals (CI) = 1.8-5.6]. Twenty-three members of the staff had a similar febrile illness (AR = 22%, 23/106); nurses were more likely to be ill than other staff (RR = 3.0, 95% CI = 1.1-11.4). Adenovirus 7 was isolated from four of the case patients and adenovirus 1 from one. The findings suggest prolonged transmission between patients and nursing staff with lack of cohorting of ill patients probably contributing to the prolongation of the outbreak. This investigation indicates that adenoviral outbreaks, although rare, can have a high mortality in severely disabled children, and that future outbreak investigations should examine the use of vaccines or antiviral agents to reduce mortality and for outbreak control.     

DTP with or after measles vaccination is associated with increased in-hospital mortality in Guinea-Bissau

BACKGROUND: The sequence of routine immunisations may be important for childhood mortality. Three doses of diphtheria-tetanus-pertussis vaccine (DTP) should be given at 6, 10, and 14 weeks and measles vaccine (MV) at 9 months of age. The sequence is not always respected. We examined in-hospital mortality of children having received DTP with or after measles vaccine. SETTING: The only paediatric ward in Bissau, Guinea-Bissau. PARTICIPANTS: Children hospitalised during two periods in 1990-1996 and 2001-2002 who had received MV prior to hospitalisation. MAIN OUTCOME MEASURE: The all-cause case fatality at the hospital for children aged 6-17 months. RESULT: The case fatality was increased for children who had received DTP with or after measles vaccine compared with children who had received measles vaccine as the most recent vaccine, the ratio being 2.53 (1.37-4.67) and 1.77 (0.92-3.41) in the two periods, respectively. The combined estimate was 2.10 (1.34-3.28). These results were not explained by differences in nutritional status, number of doses of DTP or discharge policy. CONCLUSION: Administration of DTP with, or after MV, may reduce the beneficial effect of MV.     

Measles epidemic in Harare, Zimbabwe, despite high measles immunization coverage rates.

Despite rapidly increasing measles immunization coverage in Harare city, measles remains endemic, and regular outbreaks occur. The most recent occurred in 1988, when the measles immunization coverage was 83%. We have carried out a retrospective study of the clinical and epidemiological features of this outbreak to assess whether the present immunization policy needs to be changed. Of 4357 cases of measles seen at primary health care centres and hospitals in Harare during the outbreak, 1399 (32%) were severe or involved complications that required hospital admission. The peak incidence occurred among under-2-year-olds, followed by that among 5-7-year-olds. Poor nutritional status was significantly more frequent among children who were hospitalized and among those who died. A total of 59% of all cases aged 9-59 months had documented evidence of measles immunization. The most frequent complications, which occurred most often among under-5-year-olds, were diarrhoea with dehydration, pneumonia, laryngotracheobronchitis, and convulsions, which together affected 56% of hospitalized cases. The hospital case fatality rate was low (1.43%). In Harare, measles transmission remains a problem, despite high measles immunization coverage rates; the failure rate for the standard Schwarz measles vaccine also appears to be high. There is a need to reduce the number of measles cases among under-9-month-olds and young children. Further studies into alternative measles vaccines and schedules are required.     

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。     

Measles, immunisation and disease: situation analysis in a resettlement area of northern India

India has a goal of covering all infants with measles immunization between 9-12 months. The present study was conducted in a resettlement area of east Delhi, with a population of nearly one lac, to assess the extent of measles immunization and infection among children aged under three years. All the 21 blocks of the area were covered and 10% households were selected by systematic random sampling from each of the blocks to provide 944 households and 517 under-3 children, who were individually examined by a doctor. Two hundred and eighty one children aged 12 months or above were immunized at or after 9 months giving a coverage of 74.14%. Among the immunized children 7.78% and 8.36% were vaccinated before and after the recommended age-range (9-12 months) respectively. One fifth of the children aged 12 months or above were not immunized against measles at all. Among the surviving under-3 children, no child suffered measles before 6 months but 11.86% of the children had measles between 6-8 months. Six children were vaccinated even after measles episode and seven children had measles even after immunization. Systematic community contact and special attention to resistant and hostile parents is important in order to accomplish 100% coverage. In view of the sizeable proportion of measles infection among the age group of 6-8 months, there is a case for bringing forward the recommended age for measles immunization, if we are to eradicate the disease.     

Increased childhood morbidity after measles is short-term in urban Bangladesh

In a 1995-1996 cohort study in the city of Dhaka, Bangladesh, morbidity in 117 hospitalized and 137 acute measles cases compared with age-matched children without measles (unexposed) was determined by weekly interview for 6 months. Compared with unexposed children, there were higher incidences of hospitalization (adjusted rate ratio (RR) = 3.1, 95% confidence interval (CI): 1.3, 7.6) and bloody diarrhea (adjusted RR = 2.7, 95% CI: 1.4, 5.1) in hospital measles cases during the 6 weeks after recruitment. Among community cohorts, there were higher incidences of bloody diarrhea (adjusted RR = 4.1, 95% CI: 1.1, 14.6), watery diarrhea (adjusted RR = 1.6, 95% CI: 0.9, 2.7), fast breathing (adjusted RR = 3.8, 95% CI: 2.1, 6.9), and the weekly point prevalence of pneumonia (adjusted prevalence ratio = 3.1, 95% CI: 1.0, 9.8) in measles cases during the same period. All measles cases regained lost weight within about 6 weeks. The prevalence of anergy to seven recall antigens 6 weeks after recruitment was higher in both hospital (adjusted odds ratio = 2.8, 95% CI: 1.2, 6.4) and community (adjusted odds ratio = 3.1, 95% CI: 1.1, 8.9) measles cases. Morbidity increased during the first 6-8 weeks after measles, but the authors found no consistent evidence of longer-term morbidity or wasting. The results support recent findings that measles is not associated with increased delayed mortality.     

Practical Observations from an Epidemiological Investigation of a Measles Outbreak in a District of India

Background:

Measles is a major cause of childhood morbidity and mortality, accounting for nearly half of the morbidity associated with global vaccine preventable diseases. Regular outbreaks of Measles are reported in India, of which only a few are investigated. This study was conducted in the Shivpuri District of Madhya Pradesh (India) to investigate and asses various epidemiological factors associated with measles outbreak.

Materials and Methods:

A cross-sectional study was carried out in 30 randomly selected sub-centers in 8 blocks of the Shivpuri District of Madhya Pradesh, covering 212 villages, selected by cluster sampling. The villages, which had reported measles cases, were extensively investigated by the field teams through extensive house-to-house surveys during 12-19 May 2004.

Results:

A total of 1204 cases with 14 deaths were reported with an attack rate of 6.2% and a case fatality rate of 1.2%. In this study, 17.7% of the cases reported post-measles complications with diarrhea as the most common post measles complication. The routine measles vaccine and Vitamin A supplementation in the area was also less than 30%.

Conclusions:

The majority of the cases had occurred in the unvaccinated children and in under 5 year old population. There are repeated outbreaks and a long delay in reporting of the cases. The occurrence of cases, in a reasonable proportion of the vaccinated population, points toward the fact that there is a possibility of a vaccine failure in older children. This study calls for an improved surveillance system, an improvement in the cold chain, and enhancements for measles vaccination if India is to achieve the goal of measles elimination.     

Measles immunization research: a review

Most global estimates indicate that more than 1 million children a year die from acute measles. The actual number of deaths may, however, be considerably higher than this. In addition, the impact of delayed mortality as a result of measles infection is only now being realized. Many months after they contract measles, children continue to experience higher levels of mortality and morbidity than those who do not. Immunization of children against measles therefore prevents mortality and morbidity not only during the acute phase but also during subsequent months. The impact of measles immunization programmes may therefore have generally been underestimated. The effects of measles infection on children during the early months of life are more damaging than those experienced by older children. Children should therefore be immunized against measles as early in life as possible, given the limitations of existing vaccines.     

Progress toward sustainable measles mortality reduction--South-East Asia Region, 1999-2002

Substantial progress has been made toward meeting the 2003 World Health Assembly goal to reduce measles deaths 50% by the end of 2005, compared with deaths in 1999. Although measles remains the leading cause of vaccine-preventable deaths among children, the World Health Organization (WHO) estimates that, during 1999-2002, global measles mortality decreased 29%, including a 19% decline among South-East Asia Region (SEAR) member countries. In June 2003, the SEAR Regional Technical Advisory Group on Immunization endorsed a Regional Strategic Plan for Measles Mortality Reduction (2003-2005). This report summarizes progress in measles control in SEAR during 1999-2002 and outlines plans for future activities in the region, which include strengthening measles surveillance, improving access to routine vaccination, and providing a second opportunity for measles immunization.     

Relationship between measles, malnutrition, and blindness: a prospective study in Indian children

A prospective study was conducted in slum children to determine the incidence of post-measles corneal disease and to clarify its relationship with nutritional status. A total of 318 cases of measles were identified over a period of 15 mo; maximum incidence was observed for children between 1-2 yr. Most of the children showed weight loss and serum proteins decrease during the acute stage of measles. Corneal lesions were observed in 3% of the children, and the lesions responded well to treatment. Serum vitamin A and RBP levels were significantly depressed during the acute stage of measles but were restored to normal 8 wk after recovery. There were no significant differences in the serum levels for those with and without eye lesions, which suggests that these lesions may not be mediated simply through the effect of infection on serum concentration of vitamin A.     

Seroconversions in unvaccinated infants: further evidence for subclinical measles from vaccine trials in Niakhar, Senegal

BACKGROUND: Increases in measles antibodies without rash-illnesses have been documented in previously vaccinated children exposed to measles cases. The phenomenon has been incompletely evaluated in young unvaccinated infants with immunity of maternal origin. METHODS: Monthly cohorts of newborns were prospectively randomized to vaccine and placebo control groups during a trial of high-titre vaccines in Niakhar, Senegal. Measles antibodies were assayed in blood samples of enrolled children collected at 5 months old, when controls received a placebo injection, and at 10 months, when the placebo group was given measles vaccine. Intensive prospective surveillance for measles was conducted throughout the trial. RESULTS: One-fifth (n = 53) of the placebo controls seroconverted, with known exposure to a measles case in only three of them. None of the seroconverters developed a measles-like rash. Sixteen-fold or greater increases in titres were noted in about one-quarter of them. Compared with placebo controls who did not seroconvert, seroconverters were more likely to have had exposure to a measles case and to travel, more likely to be boys than girls, and had significantly lower baseline antibody titres. Measles was endemic in the study area throughout the trial. Seroconversions did not adversely effect subsequent nutritional indices or mortality. CONCLUSIONS: Although laboratory errors and inadvertent injection of vaccine rather than placebo may have played some role, they do not fully explain the above observations, which are consistent with subclinical measles in the seroconverters. The possible role of subclinical measles in occult transmission, its potential effect on the type and duration of subsequent immunity, and its impact on response to primary vaccination need to be determined.     

深圳市流动儿童麻疹流行病学特征及发病影响因素分析

  目的   调查深圳市流动儿童麻疹病例的发病特征及导致麻疹发病的影响因素。   方法   采用描述性流行病学方法分析深圳市法定传染病报告系统报告的流动儿童麻疹病例数据, 采用群组病例对照研究方法调查其中89例病例组与相应对照组以探讨可能的影响因素。   结果   2016-2018年共报告流动儿童麻疹病例108例, 发病呈现逐年下降趋势(χ_趋势2=68.35, P < 0.001)。研究结果显示, 影响流动儿童麻疹发病的危险因素包括7~21 d前就诊史(OR=7.80, 95% CI:3.51~17.35, P < 0.001)、7~21 d前去过人口密集的场所(OR=3.37, 95% CI:1.52~7.47, P=0.002)、7~21 d前有发热-出疹病人接触史(OR=4.57, 95% CI:1.41~14.84, P=0.007), 而按计划免疫规划接种则为麻疹发病的保护因素(OR=0.12, 95% CI:0.04~0.32, P < 0.001)。   结论   流动儿童必须进一步加强疫苗接种, 医疗机构应避免成为麻疹传播的关键场所, 同时加强麻疹宣教。