Measles incidence before and after mass vaccination campaigns in Burkina Faso

Burkina Faso conducted mass measles vaccination campaigns among children aged 9 months to 4 years during December 1998 and December 1999. The 1998 campaign was limited to six cities and towns, while the 1999 campaign was nationwide. The last year of explosive measles activity in Burkina Faso was 1996. Measles surveillance data suggest that the 1998 urban campaigns did not significantly impact measles incidence. After the 1999 national campaign, the total case count decreased during 2000 and 2001. However, 68% of measles cases occurred among children aged 5 years or older who were not included in the mass vaccination strategy. During 2000 and 2001, areas with high measles incidence were characterized by low population density and presence of mobile and poor populations. Measles control strategies in Sahelian Africa must balance incomplete impact on virus circulation with cost of more aggressive strategies that include older age groups.     

Measles vaccination coverage during poliomyelitis national immunization days in Burkina Faso, 1999

In 1999, Burkina Faso added measles vaccine during the second round of its poliomyelitis national immunization days (NIDs). A cluster survey was conducted in each of the country's 53 health districts to assess vaccination coverage achieved by the campaign. Forty-four percent of children aged 9-59 months had a documented prior measles vaccination, and 88% were vaccinated during NIDs. Eighty-five percent of children not previously vaccinated received measles vaccine during the campaign. Although routine vaccination coverage varied substantially among children from various socioeconomic groups, the campaign appeared to almost equally reach all groups of children surveyed. Poliovirus vaccine coverage was 90% when measles vaccine was added to the campaign, compared with 88% during the first round. In Burkina Faso, the addition of measles vaccine to poliomyelitis NIDs achieved greater equity in measles vaccination coverage according to a number of socioeconomic factors without compromising the coverage of poliovirus vaccination.     

Progress toward measles elimination in Romania after a mass vaccination campaign and implementation of enhanced measles surveillance

In response to an outbreak of >33,000 measles cases in 1996-1998 and to prevent an outbreak predicted for 2002, Romania conducted a nationwide measles-rubella vaccination campaign in October 1998. Some 2.1 million children aged 7-18 years were vaccinated. Data from national surveillance and seroprevalence studies conducted in three districts were used to assess the campaign and status of measles control. Surveillance data showed a dramatic drop in measles despite enhanced surveillance starting in October 1999. From October 1999 to December 2001, 400 suspected measles cases were reported, down from about 5000 cases annually in non-outbreak years. Only 29 (8%) of 386 cases with specimens were laboratory confirmed; 14 were clinically confirmed. Seroprevalence estimates showed high measles antibody levels before (92.9%) and after (94.4%) the campaign. The low number of laboratory-confirmed cases and high population immunity suggest that interruption of indigenous measles virus transmission is a real possibility for Romania.     

Failure of targeted urban supplemental measles vaccination campaigns (1997-1999) to prevent measles epidemics in Mozambique (1998-2001)

This study assessed the effect of urban supplemental measles vaccination campaigns (1997-1999) in Mozambique that targeted children aged 9-59 months. Reported measles cases were analyzed to the end of 2001 to determine campaign impact. Hospital inpatient data were collected in the national capital and in three provincial capitals where epidemics occurred the year after the campaigns. Measles epidemics followed campaigns in the capital city, in 4 of 9 provincial capitals, and in 39 of 126 districts. Reasons for limited campaign impact included a low proportion of urban dwellers, the geographic location of some provincial capitals, the limited target age group, and low routine and campaign coverage. Routine immunization and disease surveillance should be strengthened and campaigns must achieve >90% coverage and target wider age groups and geographic areas in order to reach a high proportion of persons susceptible to measles.     

Measles incidence, vaccine efficacy, and mortality in two urban African areas with high vaccination coverage

Measles incidence, vaccine efficacy, and mortality were examined prospectively in two districts in Bissau where vaccine coverage for children aged 12-23 months was 81% (Bandim 1) and 61% (Bandim 2). There was little difference in cumulative measles incidence before 9 months of age (6.1% and 7.6%, respectively). Between 9 months and 2 years of age, however, 6.1% contracted measles in Bandim 1 and 13.7% in Bandim 2. Even adjusting for vaccination status, incidence was significantly higher in Bandim 2 (relative risk 1.6, P = .04). Even though 95% of the children had measles antibodies after vaccination, vaccine efficacy was not more than 68% (95% confidence interval [CI] 39%-84%) and was unrelated to age at vaccination. Unvaccinated children had a mortality hazard ratio of 3.0 compared with vaccinated children (P = .002), indicating a protective efficacy against death of 66% (CI 32%-83%) of measles vaccination. These data suggest that it will be necessary to vaccinate before age 9 months to control measles in hyperendemic urban African areas.     

Progress toward interruption of endemic measles transmission in Tunisia

Measles was the second leading cause of infant mortality in Tunisia prior to introduction of measles vaccination in 1979. The number of reported measles cases has decreased from 3007 in 1981 to 47 cases in 2000 due in part to the high coverage rates achieved after 1992. During 1998, a measles catch-up campaign vaccinated 1,846,657 children (95%) aged 6-16 years, and a follow-up campaign for children aged 9 months to 5 years in 2001 reached 547,766 (94%). During 1999-2001, 1717 cases of rash and fever illness were tested for measles; only 3 (0.2%) were positive for measles. From February to July 2002, an outbreak of measles involving 87 cases occurred in Tunisia in a health care setting and 56 (64%) patients were aged 15-30 years. The low number of laboratory-confirmed measles cases during 1999-2001 suggests endemic measles transmission may have been interrupted.     

Measles in Mexico, 1941-2001: interruption of endemic transmission and lessons learned

In Mexico, measles occurred in a cyclical endemic-epidemic pattern until the early 1970s. Beginning in 1973, routine vaccination augmented by mass vaccination campaigns led to a decrease in the incidence of measles until the 1989-1990 regional pandemic, when the measles attack rate rose to 80 cases per 100000, resulting in 5899 deaths. Since the pandemic, measles elimination efforts in Mexico have resulted in increasing coverage to >95% among children aged 1-6 years with 2 doses of either measles or measles-mumps-rubella vaccine since 1996 and in coverage of 97.6% among children aged 6-10 since 1999. Surveillance data suggest that the transmission of indigenous measles virus was interrupted in 1997. After almost 4 years without measles cases, in April 2000, measles virus was reintroduced into Mexico and 30 laboratory-confirmed cases were reported. Detection of relatively few cases in nonprogrammatic age groups affirms the high immunization coverage and the sensitivity of measles surveillance in Mexico. We conclude that the specific strategies adopted for measles elimination have enabled Mexico to eliminate the endemic transmission of measles.     

Use of administrative data to estimate mass vaccination campaign coverage,Burkina Faso, 1999

Administrative coverage data are commonly used to assess coverage of mass vaccination campaigns. These estimates are obtained by dividing the number of doses administered by the number of children of eligible age, usually at the health district level. This study used data from a cluster survey conducted in each of the 53 Burkina Faso health districts immediately after 1999 the National Immunization Days to assess whether administrative estimates correlated with those obtained through survey and whether the former identified districts that achieved suboptimal coverage as measured by cluster survey. During the first round of the campaign there was no significant correlation between data obtained by either method. The correlation was only marginally better during the second round. Although useful to help plan the logistics of a campaign, administrative coverage data should be used with other evaluation techniques in order to determine the number of eligible children vaccinated during a mass campaign.     

Vaccinated children get milder measles infection: a community study from Guinea-Bissau

We studied the occurrence of measles in vaccinated children from an urban area of Guinea-Bissau where measles causes high mortality. Vaccinated children who developed measles required more-intense exposure to become infected (they had a higher ratio of secondary cases [infected in the house] to index cases [infected outside the house]), had a lower mortality among secondary cases, and were less infectious (they generated fewer secondary cases than did unvaccinated children with measles). The attack rate among vaccinated children was significantly higher in households in which someone died of measles. Both severity of infection and development of measles in vaccinated children were related to intensity of exposure. Vaccine efficacy was 72%, and 33% of cases occurred among vaccinated children; however, most mothers remained confident that vaccinated children get milder measles. Moreover, there was significantly greater vaccination coverage among younger siblings of vaccinated children who had contracted measles than among other children in the community.     

Impact of mass measles campaigns among children less than 5 years old in Uganda

In 1999-2001, a national measles control strategy was implemented in Uganda, including routine immunization and mass vaccination campaigns for children aged 6 months to 5 years. This study assesses the impact of the campaigns on measles morbidity and mortality. Measles cases reported from 1992 through 2001 were obtained from the Health Management Information System, and measles admissions and deaths were assessed in six sentinel hospitals. Measles incidence declined by 39%, measles admissions by 60%, and measles deaths by 63% in the year following the campaigns, with impact lasting 15 to 22 months. Overall, 64% of measles cases were among children <5 years of age, and 93% were among children 相似文献   

Interruption of indigenous measles transmission in Bolivia since October 2000

Measles incidence in Bolivia declined after the introduction of campaign strategies in the 1980s. From 1990 to 1993, the peak incidence of measles (59 cases/100,000 population) was in 1992. In 1994, after the goal of interruption of measles transmission was adopted, a national vaccination campaign targeting children <15 years old was conducted and achieved 96% coverage. During 1995-1997, cases declined, although routine coverage was <90% in most years. During 1998-2000, a nationwide epidemic occurred among 2567 case-patients, most of whom were unvaccinated. A national vaccination campaign, with strong supervision, was conducted during November and December 1999 and targeted areas with low coverage. Only 122 cases were confirmed in 2000, with the last confirmed case occurring in October. Crucial to the control of the outbreak were sufficient resources and political support, intensive local planning, door-to-door vaccination with strict supervision, and rapid house-to-house coverage monitoring that improved accountability at the local level and timely and thorough outbreak investigations.     

Successful control and impending elimination of measles in the Islamic Republic of Iran

Measles is still one of the most common infectious killers of children in the world, especially in developing countries. In Iran, during the prevaccine era, 150,000-500,000 cases of measles were reported annually, with a death rate of 10%-15%. After the establishment of Expanded Program on Immunization program in 1984, vaccination rates for the first and second doses of measles vaccine increased to >90% by the mid-1990s, and the number of measles cases decreased to 2652 in 1996. In response to increased numbers of cases in older age groups during 1996-2002, a nationwide measles-rubella vaccination campaign was conducted in 2003, and 33,100,000 persons (99%) aged 5-25 years were vaccinated. During 2004-2009, 221 laboratory-confirmed measles cases (<1 case per million population) were detected, primarily in rural areas and among migrant groups who traveled to or came from high-incidence countries. High routine immunization coverage, low disease incidence, and surveillance system data suggest that interruption of endemic virus transmission might have already been achieved in Iran, but challenges remain and continued efforts are needed to sustain this accomplishment.     

Integrating insecticide-treated bednets into a measles vaccination campaign achieves high, rapid and equitable coverage with direct and voucher-based methods

Population coverage of insecticide-treated nets (ITNs) in Africa falls well below the Abuja target of 60% while coverage levels achieved during vaccination campaigns in the same populations typically exceed 90%. Household (HH) cost of ITNs is an important barrier to their uptake. We investigated the coverage, equity and cost of linking distribution of free ITNs to a measles vaccination campaign. During a national measles vaccination campaign in Zambia, children in four rural districts were given a free ITN when they received their measles vaccination. In one urban district, children were given a voucher, which could be redeemed for a net at a commercial distribution site. About 1700 HHs were asked whether they received vaccination and an ITN during a measles campaign, as well as questions on assets (e.g. type roofing material or bicycle ownership) to assess HH wealth. Net ownership was calculated for children in each wealth quintile. In the rural areas, ITN coverage among children rose from 16.7% to 81.1% and the equity ratio from 0.32 to 0.88 and in the urban area from 50.7% to 76.2% (equity ratio: 0.66-1.19). The operational cost per ITN delivered was dollar 0.35 in the rural area with direct distribution and $1.89 in the urban areas with voucher distribution. Mass distribution of ITNs through vaccination campaigns achieves rapid, high and equitable coverage at low cost.     

Improved equity in measles vaccination from integrating insecticide‐treated bednets in a vaccination campaign,Madagascar

Objective To evaluate the effect of integrating ITN distribution on measles vaccination campaign coverage in Madagascar. Methods Nationwide cross‐sectional survey to estimate measles vaccination coverage, nationally, and in districts with and without ITN integration. To evaluate the effect of ITN integration, propensity score matching was used to create comparable samples in ITN and non‐ITN districts. Relative risks (RR) and 95% confidence intervals (CI) were estimated via log‐binomial models. Equity ratios, defined as the coverage ratio between the lowest and highest household wealth quintile (Q), were used to assess equity in measles vaccination coverage. Results National measles vaccination coverage during the campaign was 66.9% (95% CI 63.0–70.7). Among the propensity score subset, vaccination campaign coverage was higher in ITN districts (70.8%) than non‐ITN districts (59.1%) (RR = 1.3, 95% CI 1.1–1.6). Among children in the poorest wealth quintile, vaccination coverage was higher in ITN than in non‐ITN districts (Q1; RR = 2.4, 95% CI 1.2–4.8) and equity for measles vaccination was greater in ITN districts (equity ratio = 1.0, 95% CI 0.8–1.3) than in non‐ITN districts (equity ratio = 0.4, 95% CI 0.2–0.8). Conclusion Integration of ITN distribution with a vaccination campaign might improve measles vaccination coverage among the poor, thus providing protection for the most vulnerable and difficult to reach children.     

2008年新疆维吾尔自治区实施麻疹疫苗后续强化免疫活动评价

目的探讨加速控制和消除麻疹的策略和措施。方法 2008年对新疆维吾尔自治区全区范围8月龄～6岁儿童实施了麻疹疫苗（MV）后续免疫活动;利用新疆维吾尔自治区统计局资料、疫苗分发数、疫情资料等,对报告接种情况进行了评价。结果全疆麻疹强化免疫应种儿童1641861人,实际免疫儿童1616117人,接种率为98.99%,以县为单位报告接种率95%以上。结论开展MV初始强化免疫和后续强化免疫对控制麻疹效果非常显著。     

Measles epidemiology and elimination strategies in Turkey

In Turkey, 15,000-30,000 measles cases have been reported annually since the 1990s. Epidemics occur every 3-4 years, and >/=90% of cases are <15 years old. The high incidence is due to inadequate vaccination coverage (nationally 84% in 2001) and immunity provided by the first dose of vaccine administered at age 9 months. The second dose, which has been recommended for first grade students since 1998, has been insufficient to provide the herd immunity necessary to control measles. The Ministry of Health launched a comprehensive program for 2002-2010 targeting measles elimination. This plan calls for a national vaccination campaign among all children aged 9 months to 14 years and routine two-dose vaccination coverage will be increased to >/=95% or follow-up campaigns will be conducted in areas not achieving high coverage levels. Also, all military recruits in 2002-2009 will be vaccinated and case-based, laboratory supported surveillance will be initiated.     

A large rubella outbreak, Romania--2003

Romania experienced a large rubella outbreak in 2002-03, with more than 115,000 reported cases nationwide, and an incidence of 531 reported cases per 100,000 population. The incidence was highest in children of school age. The cohorts of adolescent girls vaccinated in 1998 and 2002 (when a rubella-containing vaccine was available) had significantly lower incidence rates (p<0.001) compared with those in boys in the same age groups who were not vaccinated. In 2003, of the 150 suspected congenital rubella syndrome (CRS) cases reported, seven (4.6%) were confirmed by positive rubella IgM antibodies. In the absence of available rubella containing vaccine for outbreak control, an outbreak response plan to improve the detection of cases and to limit rubella virus transmission was developed. The following activities were conducted: surveillance of pregnant women with suspected rubella or history of exposure to rubella virus was implemented, with follow up of pregnancy outcomes; surveillance for CRS was strengthened; existing infection control guidelines to prevent disease transmission within healthcare facilities were reinforced; and a communication plan was developed. In May 2004, Romania is introducing measles, mumps and rubella (MMR) vaccine for routine vaccination of children aged 12 to 15 months, while continuing vaccination of girls in the 8th grade of school (13-14 years of age) with rubella-only vaccine.     

Vaccination levels associated with lack of measles transmission among preschool-aged populations in the United States, 1989-1991

Knowledge of the minimum level of vaccination capable of preventing measles transmission in an age group is helpful for establishing program targets for measles elimination. In 1990, during the measles resurgence in the United States, one-half of cases occurred in children aged <5 years. Although estimated population immunity among persons >or=6 years of age was 93%, immunity was lower and varied widely among preschool-aged children. To examine the association of vaccine coverage at 2 years of age and measles incidence among preschool-aged children, we analyzed ecological studies of measles incidence in Milwaukee (Wisconsin) census tracts, Dallas (Texas) ZIP code areas, and selected cities during the 1989-1991 measles resurgence. In each study area, measles incidence decreased rapidly with increasing measles vaccine coverage and became low or negligible when coverage was >or=80%. Regression analysis also suggested that measles would not be transmitted when vaccine coverage was at least 79%. A minimum vaccine coverage of approximately 80% at the second birthday in census tracts, ZIP code areas, and cities in the United States may be sufficient to prevent measles transmission among preschool-aged children if population immunity is >or=93% among persons >or=6 years of age.     

Humoral and cell-mediated immune responses to an early 2-dose measles vaccination regimen in the United States

BACKGROUND: Shifts in peak measles incidence to children <12 months old and the associated high mortality support the study of an early 2-dose measles vaccine regimen. METHODS: Fifty-five infants were vaccinated with measles vaccine at age 6 (n=32) or 9 (n=23) months, followed by measles-mumps-rubella (MMR)-II vaccine at age 12 months. A control group received MMR-II only at age 12 months. Measles-specific humoral and cell-mediated immunity were evaluated before, 12 weeks after measles immunization, and 24 weeks after MMR-II. RESULTS: Measles-specific T cell proliferation after both doses of vaccine was equivalent, regardless of age or the presence of passive antibodies. Seroconversion rates, geometric mean titers, and the percentage of infants with antibody titers >120 mIU after the first measles vaccine were lower in infants vaccinated at age 6 months, regardless of the presence of passive antibodies, but measles humoral responses increased after the administration of MMR-II vaccine in children initially vaccinated at age 6 or 9 months. CONCLUSION: Measles vaccination elicits T cell responses in infants as young as 6 months old, which may prime the humoral response to the second dose. Initiating measles vaccination as an early 2-dose regimen results in an immunologic response that is likely to have clinical benefits in developed and developing countries.     

2008年桂林市麻疹流行分析

目的了解桂林市麻疹发病情况,为控制麻疹制定科学依据。方法采用描述流行病学方法统计分析。结果 2008年全市报告麻疹病例192例,报告发病率3.87/10万,<8月龄51例,占总病例数的26.6%,>15岁病例51例,占26.6%,散居儿童发病125例,占65.1%;病例以市区为主,占病例数的52.6%,主要集中在流动人口较多的城乡结合部;病例中未免疫的128例,免疫史不祥的52例,分别占总病例数的66.7%、27.1%。结论桂林市麻疹发病以小年龄婴儿和成人为主,要控制麻疹,在做好常规免疫工作的同时,必须加强流动人口的管理,提高流动儿童的接种率。