COVID-19 Vaccination Coverage - World Health Organization African Region, 2021-2023.

With the availability of authorized COVID-19 vaccines in early 2021, vaccination became an effective tool to reduce COVID-19-associated morbidity and mortality. Initially, the World Health Organization (WHO) set an ambitious target to vaccinate 70% of the global population by mid-2022. However, in July 2022, WHO recommended that all countries, including those in the African Region, prioritize COVID-19 vaccination of high-risk groups, including older adults and health care workers, to have the greatest impact on morbidity and mortality. As of December 31, 2023, approximately 860 million doses of COVID-19 vaccine had been delivered to countries in the African Region, and 646 million doses had been administered. Cumulatively, 38% of the African Region's population had received ≥1 dose, 32% had completed a primary series, and 21% had received ≥1 booster dose. Cumulative total population coverage with ≥1 dose ranged by country from 0.3% to 89%. Coverage with the primary series among older age groups was 52% (range among countries = 15%-96%); primary series coverage among health care workers was 48% (range = 13%-99%). Although the COVID-19 public health emergency of international concern was declared over in May 2023, current WHO recommendations reinforce the need to vaccinate priority populations at highest risk for severe COVID-19 disease and death and build more sustainable programs by integrating COVID-19 vaccination into primary health care, strengthening immunization across the life course, and improving pandemic preparedness.

Progress Toward Rubella and Congenital Rubella Syndrome Elimination - Worldwide, 2012-2022.

Rubella virus is a leading cause of vaccine-preventable birth defects. Infection during pregnancy can result in miscarriage, fetal death, stillbirth, or a constellation of birth defects, including cataracts, deafness, heart defects, and developmental delay, known as congenital rubella syndrome (CRS). A single dose of rubella-containing vaccine can provide lifelong protection against rubella. The Global Vaccine Action Plan 2011-2020 included a target to achieve elimination of rubella in at least five of the six World Health Organization (WHO) regions by 2020, and rubella elimination is a critical goal of the Immunization Agenda 2030. This report updates a previous report and describes progress toward rubella and CRS elimination during 2012-2022. During 2012-2022, among 194 WHO countries, the number that included rubella-containing vaccine (RCV) in their immunization schedules increased from 132 (68%) to 175 (90%) and the percentage of the world's infants vaccinated against rubella increased from 40% to 68%. Reported rubella cases declined 81%, from 93,816 in 2012 to 17,407 in 2022. Verification of rubella elimination was achieved in 98 (51%) of 194 countries by 2022, an increase from 84 (43%) countries in 2019. Despite significant progress in the introduction of RCV into routine immunization programs worldwide, approximately 25 million infants annually still do not have access to RCV. Nevertheless, even in complex settings, the increasing number of countries that have achieved and sustained rubella elimination demonstrates progress toward global rubella elimination.

Progress Toward Measles Elimination - South-East Asia Region, 2003-2020.

In 2013, member states of the World Health Organization (WHO) South-East Asia Region* (SEAR) adopted the goal of measles elimination and rubella and congenital rubella syndrome control† by 2020 (1). In 2014, to provide impetus toward achieving this goal, the Regional Director declared measles elimination and rubella control one of the Regional Flagship Priorities. In 2019, SEAR member states declared a revised goal of eliminating both measles and rubella§ by 2023 (2). The recommended strategies to achieve elimination include 1) achieving and maintaining ≥95% coverage with 2 doses of measles- and rubella-containing vaccine in every district through routine or supplementary immunization activities¶ (SIAs); 2) developing and sustaining a sensitive and timely case-based surveillance system that meets recommended performance indicators**; 3) developing and maintaining an accredited laboratory network; 4) achieving timely identification, investigation, and response to measles outbreaks; and 5) collaborating with other public health initiatives to achieve the preceding four strategies. This report updates a previous report and describes progress toward measles elimination in SEAR during 2003-2020 (3). In 2002, coverage with the first dose of a measles-containing vaccine in routine immunization (MCV1) was 70%, and only three countries in SEAR had added a second routine dose of measles-containing vaccine in routine immunization (MCV2). During 2003-2020, all countries introduced MCV2, and estimated coverage with MCV1 increased 35%, from 65% to 88%, and coverage with MCV2 increased 1,233% from 6% to 80%. Approximately 938 million persons were vaccinated in SIAs. Annual reported measles incidence declined by 92%, from 57.0 to 4.8 cases per 1 million population, and estimated deaths decreased by 97%; an estimated 9.3 million deaths were averted by measles vaccination. By 2020, five countries were verified as having achieved measles elimination. To achieve measles elimination in the region by 2023, additional efforts are urgently needed to strengthen routine immunization services and improve measles-containing vaccine (MCV) coverage, conduct periodic high-quality SIAs, and strengthen measles case-based surveillance and laboratory capacity.

Progress Toward Regional Measles Elimination - Worldwide, 2000-2020.

In 2012, the World Health Assembly endorsed the Global Vaccine Action Plan,* with the objective of eliminating measles† in five of the six World Health Organization (WHO) regions by 2020 (1). The Immunization Agenda 2021-2030 (IA2030)§ uses measles incidence as an indicator of the strength of immunization systems. The Measles-Rubella Strategic Framework 2021-2030¶ and the Measles Outbreaks Strategic Response Plan 2021-2023** are aligned with the IA2030 and highlight robust measles surveillance systems to document immunity gaps, identify root causes of undervaccination, and develop locally tailored solutions to ensure administration of 2 doses of measles-containing vaccine (MCV) to all children. This report describes progress toward World Health Assembly milestones and measles elimination objectives during 2000-2020 and updates a previous report (2). During 2000-2010, estimated MCV first dose (MCV1) coverage increased globally from 72% to 84%, peaked at 86% in 2019, but declined to 84% in 2020 during the COVID-19 pandemic. All countries conducted measles surveillance, although fewer than one third achieved the sensitivity indicator target of ≥2 discarded†† cases per 100,000 population in 2020. Annual reported measles incidence decreased 88% during 2000-2016, from 145 to 18 cases per 1 million population, rebounded to 120 in 2019, before falling to 22 in 2020. During 2000-2020, the annual number of estimated measles deaths decreased 94%, from 1,072,800 to 60,700, averting an estimated 31.7 million measles deaths. To achieve regional measles elimination targets, enhanced efforts are needed to reach all children with 2 MCV doses, implement robust surveillance, and identify and close immunity gaps.

Development of a Measles and Rubella Multiplex Bead Serological Assay for Assessing Population Immunity.

Serosurveys are important tools for estimating population immunity and providing immunization activity guidance. The measles and rubella multiplex bead assay (MBA) offers multiple advantages over standard serological assays and was validated by comparison with the enzyme-linked immunosorbent assay (ELISA) and the measles plaque reduction neutralization (PRN) assay. Results from a laboratory-produced purified measles virus whole-virus antigen MBA (MeV WVAL) correlated better with ELISA and PRN than results from the baculovirus-expressed measles nucleoprotein (N) MBA. Therefore, a commercially produced whole-virus antigen (MeV WVAC) was evaluated. Serum IgG antibody concentrations correlated significantly with a strong linear relationship between the MeV WVAC and MeV WVAL MBAs (R = 0.962 and R2 = 0.926). IgG concentrations from the MeV WVAC MBA showed strong correlation with PRN titers (R = 0.846), with a linear relationship comparable to values obtained with the MeV WVAL MBA and PRN assay (R2 = 0.716 and R2 = 0.768, respectively). Receiver operating characteristic (ROC) curve analysis of the MeV WVAC using PRN titer as the comparator resulted in a seroprotection cutoff of 153 mIU/ml, similar to the established correlate of protection of 120 mIU/ml, with a sensitivity of 98% and a specificity of 83%. IgG concentrations correlated strongly between the rubella WVA MBA and ELISA (R = 0.959 and R2 = 0.919). ROC analysis of the rubella MBA using ELISA as the comparator yielded a cutoff of 9.36 IU/ml, similar to the accepted cutoff of 10 IU/ml for seroprotection, with a sensitivity of 99% and a specificity of 100%. These results support use of the MBA for multiantigen serosurveys assessing measles and rubella population immunity.

Progress Toward Regional Measles Elimination - Worldwide, 2000-2019.

In 2010, the World Health Assembly (WHA) set the following three milestones for measles control to be achieved by 2015: 1) increase routine coverage with the first dose of measles-containing vaccine (MCV1) among children aged 1 year to ≥90% at the national level and to ≥80% in every district, 2) reduce global annual measles incidence to <5 cases per 1 million population, and 3) reduce global measles mortality by 95% from the 2000 estimate* (1). In 2012, WHA endorsed the Global Vaccine Action Plan,† with the objective of eliminating measles§ in five of the six World Health Organization (WHO) regions by 2020. This report describes progress toward WHA milestones and regional measles elimination during 2000-2019 and updates a previous report (2). During 2000-2010, estimated MCV1 coverage increased globally from 72% to 84% but has since plateaued at 84%-85%. All countries conducted measles surveillance; however, approximately half did not achieve the sensitivity indicator target of two or more discarded measles and rubella cases per 100,000 population. Annual reported measles incidence decreased 88%, from 145 to 18 cases per 1 million population during 2000-2016; the lowest incidence occurred in 2016, but by 2019 incidence had risen to 120 cases per 1 million population. During 2000-2019, the annual number of estimated measles deaths decreased 62%, from 539,000 to 207,500; an estimated 25.5 million measles deaths were averted. To drive progress toward the regional measles elimination targets, additional strategies are needed to help countries reach all children with 2 doses of measles-containing vaccine, identify and close immunity gaps, and improve surveillance.

Progress Toward Rubella Elimination - Western Pacific Region, 2000-2019.

Rubella is the leading vaccine-preventable cause of birth defects. Rubella typically manifests as a mild febrile rash illness; however, infection during pregnancy, particularly during the first trimester, can result in miscarriage, fetal death, or a constellation of malformations known as congenital rubella syndrome (CRS), commonly including one or more visual, auditory, or cardiac defects (1). In 2012, the Regional Committee of the World Health Organization (WHO) Western Pacific Region (WPR)* committed to accelerate rubella control, and in 2017, resolved that all countries or areas (countries) in WPR should aim for rubella elimination† as soon as possible (2,3). WPR countries are capitalizing on measles elimination activities, using a combined measles and rubella vaccine, case-based surveillance for febrile rash illness, and integrated diagnostic testing for measles and rubella. This report summarizes progress toward rubella elimination and CRS prevention in WPR during 2000-2019. Coverage with a first dose of rubella-containing vaccine (RCV1) increased from 11% in 2000 to 96% in 2019. During 1970-2019, approximately 84 million persons were vaccinated through 62 supplementary immunization activities (SIAs) conducted in 27 countries. Reported rubella incidence increased from 35.5 to 71.3 cases per million population among reporting countries during 2000-2008, decreased to 2.1 in 2017, and then increased to 18.4 in 2019 as a result of outbreaks in China and Japan. Strong sustainable immunization programs, closing of existing immunity gaps, and maintenance of high-quality surveillance to respond rapidly to and contain outbreaks are needed in every WPR country to achieve rubella elimination in the region.

Progress Toward Measles Elimination - Eastern Mediterranean Region, 2013-2019.

In 1997, during the 41st session of the Regional Committee for the Eastern Mediterranean, the 21 countries in the World Health Organization (WHO) Eastern Mediterranean Region* (EMR) passed a resolution to eliminate† measles (1). In 2015, this goal was included as a priority in the Eastern Mediterranean Vaccine Action Plan 2016-2020 (EMVAP) (2), endorsed at the 62nd session of the Regional Committee (3). To achieve this goal, the WHO Regional Office for the Eastern Mediterranean developed a four-pronged strategy: 1) achieve ≥95% vaccination coverage with the first dose of measles-containing vaccine (MCV1) among children in every district of each country through routine immunization services; 2) achieve ≥95% vaccination coverage with a second MCV dose (MCV2) in every district of each country either through implementation of a routine 2-dose vaccination schedule or through supplementary immunization activities§ (SIAs); 3) conduct high-quality, case-based surveillance in all countries; and 4) provide optimal measles clinical case management, including dietary supplementation with vitamin A (4). This report describes progress toward measles elimination in EMR during 2013-2019 and updates a previous report (5). Estimated MCV1 coverage increased from 79% in 2013 to 82% in 2018. MCV2 coverage increased from 59% in 2013 to 74% in 2018. In addition, during 2013-2019, approximately 326.4 million children received MCV during SIAs. Reported confirmed measles incidence increased from 33.5 per 1 million persons in 2013 to 91.2 in 2018, with large outbreaks occurring in Pakistan, Somalia, and Yemen; incidence decreased to 23.3 in 2019. In 2019, the rate of discarded nonmeasles cases¶ was 5.4 per 100,000 population. To achieve measles elimination in the EMR, increased visibility of efforts to achieve the measles elimination goal is critically needed, as are sustained and predictable investments to increase MCV1 and MCV2 coverage, conduct high-quality SIAs, and reach populations at risk for not accessing immunization services or living in areas with civil strife.

Progress Toward Measles Elimination - Pakistan, 2000-2018.

In 1997, the 21 countries in the World Health Organization (WHO) Eastern Mediterranean Region* (EMR) passed a resolution during the 41st session of the Regional Committee for the Eastern Mediterranean to eliminate measles† (1). In 2015, this goal was included as a priority in the Eastern Mediterranean Vaccine Action Plan 2016-2020 (2), approved at the 62nd session of the Regional Committee (3). To achieve measles elimination, the WHO Regional Office for the Eastern Mediterranean developed the following four-pronged strategy: 1) achieve ≥95% vaccination coverage with the first dose of measles-containing vaccine (MCV) among children in every district of each country through routine immunization services; 2) achieve ≥95% vaccination coverage with a second MCV dose in every district of each country either through implementation of a routine 2-dose vaccination schedule or through supplementary immunization activities (SIAs)§; 3) conduct high-quality, case-based measles surveillance in all countries; and 4) provide optimal measles clinical case management, including dietary supplementation with vitamin A (4). Pakistan, an EMR country with a population of approximately 200 million, accounts for nearly one third of the overall EMR population. This report describes progress and challenges toward measles elimination in Pakistan during 2000-2018. During the study period, estimated coverage with the first MCV dose (MCV1) increased from 57% in 2000 to 76% in 2017. The second MCV dose (MCV2) was introduced nationwide in 2009, and MCV2 coverage increased from 30% in 2009 to 45% in 2017. During 2000-2018, approximately 232.5 million children received doses of MCV during SIAs. Reported confirmed measles incidence increased from an average of 24.6 per 1 million persons during 2000-2009 to an average of 80.4 during 2010-2018, with peaks in 2013 (230.3) and 2018 (153.6). In 2017 and 2018, the rates of suspected cases discarded as nonmeasles after investigation were 2.1 and 1.5 per 100,000 population, reflecting underreporting of cases. To achieve measles elimination, additional efforts are needed to increase MCV1 and MCV2 coverage, develop strategies to identify and reach communities not accessing immunization services, and increase sensitivity of case-based measles surveillance in all districts.

Progress Toward Measles Elimination - European Region, 2009-2018.

In 2010, all 53 countries* in the World Health Organization (WHO) European Region (EUR) reconfirmed their commitment to eliminating measles and rubella and congenital rubella syndrome (1); this goal was included as a priority in the European Vaccine Action Plan 2015-2020 (2). The WHO-recommended elimination strategies in EUR include 1) achieving and maintaining ≥95% coverage with 2 doses of measles-containing vaccine (MCV) through routine immunization services; 2) providing measles and rubella vaccination opportunities, including supplementary immunization activities (SIAs), to populations susceptible to measles or rubella; 3) strengthening surveillance by conducting case investigations and confirming suspected cases and outbreaks with laboratory results; and 4) improving the availability and use of evidence for the benefits and risks associated with vaccination (3). This report updates a previous report (4) and describes progress toward measles elimination in EUR during 2009-2018. During 2009-2017, estimated regional coverage with the first MCV dose (MCV1) was 93%-95%, and coverage with the second dose (MCV2) increased from 73% to 90%. In 2017, 30 (57%) countries achieved ≥95% MCV1 coverage, and 15 (28%) achieved ≥95% coverage with both doses. During 2009-2018, >16 million persons were vaccinated during SIAs in 13 (24%) countries. Measles incidence declined to 5.8 per 1 million population in 2016, but increased to 89.5 in 2018, because of large outbreaks in several EUR countries. To achieve measles elimination in EUR, measures are needed to strengthen immunization programs by ensuring ≥95% 2-dose MCV coverage in every district of each country, offering supplemental measles vaccination to susceptible adults, maintaining high-quality surveillance for rapid case detection and confirmation, and ensuring effective outbreak preparedness and response.

Progress Toward Regional Measles Elimination - Worldwide, 2000-2017.

In 2010, the World Health Assembly set three milestones for measles prevention to be achieved by 2015: 1) increase routine coverage with the first dose of measles-containing vaccine (MCV1) among children aged 1 year to ≥90% at the national level and to ≥80% in every district; 2) reduce global annual measles incidence to less than five cases per million population; and 3) reduce global measles mortality by 95% from the 2000 estimate (1).* In 2012, the World Health Assembly endorsed the Global Vaccine Action Plan (GVAP),† with the objective of eliminating measles§ in four of the six World Health Organization (WHO) regions by 2015 and in five regions by 2020. Countries in all six WHO regions have adopted goals for measles elimination by 2020. This report describes progress toward global measles control milestones and regional measles elimination goals during 2000-2017 and updates a previous report (2). During 2000-2017, estimated MCV1 coverage increased globally from 72% to 85%; annual reported measles incidence decreased 83%, from 145 to 25 cases per million population; and annual estimated measles deaths decreased 80%, from 545,174 to 109,638. During this period, measles vaccination prevented an estimated 21.1 million deaths. However, measles elimination milestones have not been met, and three regions are experiencing a large measles resurgence. To make further progress, case-based surveillance needs to be strengthened, and coverage with MCV1 and the second dose of measles-containing vaccine (MCV2) needs to increase; in addition, it will be important to maintain political commitment and ensure substantial, sustained investments to achieve global and regional measles elimination goals.

Measles-Rubella Supplementary Immunization Activity Readiness Assessment - India, 2017-2018.

In 2013, during the 66th session of the Regional Committee of the World Health Organization (WHO) South-East Asia Region (SEAR), the 11 SEAR countries* adopted goals to eliminate measles and control rubella and congenital rubella syndrome by 2020† (1). To accelerate progress in India (2,3), a phased§ nationwide supplementary immunization activity (SIA)¶ using measles-rubella vaccine and targeting approximately 410 million children aged 9 months-14 years commenced in 2017 and will be completed by first quarter of 2019. To ensure a high-quality SIA, planning and preparation were monitored using a readiness assessment tool adapted from the WHO global field guide** (4) by the India Ministry of Health and Family Welfare. This report describes the results and experience gained from conducting SIA readiness assessments in 24 districts of three Indian states (Andhra Pradesh, Kerala, and Telangana) during the second phase of the SIA. In each selected area, assessments were conducted 4-6 weeks and 1-2 weeks before the scheduled SIA. At the first assessment, none of the states and districts were on track with preparations for the SIA. However, at the second assessment, two (67%) states and 21 (88%) districts were on track. The SIA readiness assessment identified several preparedness gaps; early assessment results were immediately communicated to authorities and led to necessary corrective actions to ensure high-quality SIA implementation.

Measles and rubella elimination: learning from polio eradication and moving forward with a diagonal approach.

INTRODUCTION: In 1988, an estimated 350,000 children were paralyzed by polio and 125 countries reported polio cases, the World Health Assembly passed a resolution to achieve polio eradication by 2000, and the Global Polio Eradication Initiative (GPEI) was established as a partnership focused on eradication. Today, following eradication efforts, polio cases have decreased >99% and eradication of all three types of wild polioviruses is approaching. However, since polio resources substantially support disease surveillance and other health programs, losing polio assets could reverse progress toward achieving Global Vaccine Action Plan goals. Areas covered: As the end of polio approaches and GPEI funds and capacity decrease, we document knowledge, experience, and lessons learned from 30 years of polio eradication. Expert commentary: Transitioning polio assets to measles and rubella (MR) elimination efforts would accelerate progress toward global vaccination coverage and equity. MR elimination feasibility and benefits have long been established. Focusing efforts on MR elimination after achieving polio eradication would make a permanent impact on reducing child mortality but should be done through a 'diagonal approach' of using measles disease transmission to identify areas possibly susceptible to other vaccine-preventable diseases and to strengthen the overall immunization and health systems to achieve disease-specific goals.

Hepatitis B control among children in the Eastern Mediterranean Region of the World Health Organization.

In the pre-vaccination era, the prevalence of chronic hepatitis B virus (HBV) infection in the World Health Organization (WHO) Eastern Mediterranean Region (EMR) ranged from two to seven percent in a total population of over 580 million people. Mortality estimates place cirrhosis among the top ten causes of years of life lost in the EMR. The region has made notable achievements, improving coverage from only 6% in 1992, when WHO recommended hepatitis B vaccination of all infants, to 83% in 2014. Member states adopted a hepatitis B control target in 2009 to reduce chronic hepatitis B virus infection prevalence to less than one percent among children aged <5 years by 2015. This report reviews progress toward achievement, challenges faced, and the next steps forward of hepatitis B control among children in the EMR.

Progress and peril: poliomyelitis eradication efforts in Pakistan, 1994-2013.

Pakistan is one of 3 countries where transmission of indigenous wild poliovirus (WPV) has never been interrupted. Numbers of confirmed polio cases have declined by >90% from preeradication levels, although outbreaks occurred during 2008-2013. During 2012 and 2013, 58 and 93 WPV cases, respectively, were reported, almost all of which were due to WPV type 1. Of the 151 WPV cases reported during 2012-2013, 123 (81%) occurred in the conflict-affected Federally Administered Tribal Areas (FATA) and in security-compromised Khyber Pakhtunkhwa province. WPV type 3 was isolated from only 3 persons with polio in a single district in 2012. During August 2012-December 2013, 62 circulating vaccine-derived poliovirus type 2 cases were detected, including 40 cases (65%) identified in the FATA during 2013. Approximately 350 000 children in certain districts of the FATA have not received polio vaccine during supplementary immunization activities (SIAs) conducted since mid-2012, because local authorities have banned polio vaccination. In other areas of Pakistan, SIAs have been compromised by attacks targeting polio workers, which started in mid-2012. Further efforts to reach children in conflict-affected and security-compromised areas will be necessary to prevent reintroduction of WPV into other areas of Pakistan and other parts of the world.

Trends in the risk of U.S. polio outbreaks and poliovirus vaccine availability for response.

OBJECTIVES: The United States eliminated indigenous wild polioviruses (WPVs) in 1979 and switched to inactivated poliovirus vaccine in 2000, which quickly ended all indigenous live poliovirus transmission. Continued WPV circulation and use of oral poliovirus vaccine globally allow for the possibility of reintroduction of these viruses. We evaluated the risk of a U.S. polio outbreak and explored potential vaccine needs for outbreak response. METHODS: We synthesized information available on vaccine coverage, exemptor populations, and population immunity. We used an infection transmission model to explore the potential dynamics of a U.S. polio outbreak and potential vaccine needs for outbreak response, and assessed the impacts of heterogeneity in population immunity for two different subpopulations with potentially low coverage. RESULTS: Although the risk of poliovirus introduction remains real, widespread transmission of polioviruses appears unlikely in the U.S., given high routine coverage. However, clusters of un- or underimmunized children might create pockets of susceptibility that could potentially lead to one or more paralytic polio cases. We found that the shift toward combination vaccine utilization, with limited age indications for use, and other current trends (e.g., decreasing proportion of the population with immunity induced by live polioviruses and aging of vaccine exemptor populations) might increase the vulnerability to poliovirus reintroduction at the same time that the ability to respond may decrease. CONCLUSIONS: The U.S. poliovirus vaccine stockpile remains an important resource that may potentially be needed in the future to respond to an outbreak if a live poliovirus gets imported into a subpopulation with low vaccination coverage.

Progress toward measles elimination in the Eastern Mediterranean Region.

Since 1997, when the goal of interrupting measles transmission by 2010 was adopted, substantial progress has been made toward the elimination of measles in the Eastern Mediterranean Region (EMR). For the 22 EMR member countries, routine coverage with the first dose of a measles-containing vaccine (MCV) increased from 70% in 1997 to 82% in 2009. All 22 countries conducted measles catch-up vaccination campaigns during 1994-2009, and most conducted follow-up campaigns as needed. Of the 22 EMR countries, 19 have established case-based surveillance for measles with laboratory confirmation. Reported measles cases decreased by 86% during 1998-2008, and estimated measles mortality decreased by 93% during 2000-2008, accounting for 17% of global measles mortality reduction during that period. Despite these successes, several significant challenges remain, and the EMR will not be able to achieve measles elimination by the end of 2010. Achieving and maintaining high population immunity with 2 doses of MCV, improving sensitive case-based surveillance, identifying and vaccinating high-risk subpopulation groups, and appropriately responding to outbreaks are key steps needed to achieve the goal.

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.

Toward measles elimination in Bahrain--a Middle East country experience.

Measles was a leading cause of infant and child morbidity and mortality in Bahrain before the introduction of measles vaccine in 1974. With the establishment of the Expanded Program on Immunization (EPI) in 1981 and the introduction of a second dose of measles vaccine in 1985, coverage for first and second doses of measles vaccine increased to 94% by 1997 and has been sustained >97% since 2001. Measles, mumps, and rubella (MMR) immunization campaigns targeting 12-year-old students were conducted annually during 1998-2006 and achieved coverage of >95%. As a result, the incidence of measles in Bahrain has declined markedly over the past 4 decades, to 2.7 cases per million persons in 2009. Recent confirmed measles cases have occurred sporadically, in undervaccinated children or in infants too young or adults too old to receive measles vaccine. Bahrain has made significant progress toward measles elimination by sustaining high immunization coverage and strengthening case-based measles surveillance activities. Further success will depend on improved identification and immunization of undervaccinated expatriate workers and their families.

Seroprevalence of antibody to mumps virus in the US population, 1999-2004.

BACKGROUND: In 2006, the largest mumps outbreak in the United States in 20 years occurred. To understand prior mumps seroprevalence and factors associated with the presence of antibody to mumps virus, data from the 1999-2004 National Health and Nutrition Examination Survey (NHANES) were analyzed. METHODS: A mumps virus-specific enzyme immunoassay was used to measure the seroprevalence of serum immunoglobulin G (IgG) antibody among NHANES participants aged 6-49 years. Participants were grouped on the basis of 10-year birth cohorts, 95% confidence intervals (CIs) were calculated using SUDAAN software, and logistic regression was used to identify independent predictors. RESULTS: The overall age-adjusted seroprevalence of IgG antibody to mumps virus during 1999-2004 was 90.0% (95% CI, 88.8%-91.1%). Seroprevalence was higher among US-born non-Hispanic blacks (96.4% [95% CI, 95.5%-97.2%]) and non-US-born Mexican Americans (93.7% [95% CI, 92.0%-95.2%]). Seroprevalence was significantly lower in the 1967-1976 birth cohort (85.7% [95% CI, 83.5%-87.8%]). The variables sex, education, and race/ethnicity/birthplace were independent predictors in at least 1 of the birth cohorts. CONCLUSIONS: The overall estimate of 90.0% is at the lower end of the estimated population immunity (90%-92%) needed to achieve herd immunity. Lower seroprevalence among groups suggest that they represent populations at an increased risk. For mumps control, high vaccine coverage and high population immunity must be achieved and maintained.