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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., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.

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., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.

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., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.

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., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. Matt Ferrari reports grants from the Bill and Melinda Gates Foundation, the World Health Organization (WHO), and Gavi, the Vaccine Alliance, to develop measles models and travel support from WHO to attend the Strategic Advisory Group of Experts on Vaccines (SAGE) meeting in 2019 and the Measles and Rubella SAGE working group. Allison Portnoy reports grant support from The Pennsylvania State University for time and analytic contributions to this manuscript. No other potential conflicts of interest were disclosed.

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 WVA L ) correlated better with ELISA and PRN than results from the baculovirus-expressed measles nucleoprotein (N) MBA. Therefore, a commercially produced whole-virus antigen (MeV WVA C ) was evaluated. Serum IgG antibody concentrations correlated significantly with a strong linear relationship between the MeV WVA C and MeV WVA L MBAs ( R  = 0.962 and R 2 = 0.926). IgG concentrations from the MeV WVA C MBA showed strong correlation with PRN titers ( R  = 0.846), with a linear relationship comparable to values obtained with the MeV WVA L MBA and PRN assay ( R 2 = 0.716 and R 2 = 0.768, respectively). Receiver operating characteristic (ROC) curve analysis of the MeV WVA C 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 R 2 = 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., (Copyright © 2021 American Society for Microbiology.)

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., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.

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., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.

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., Competing Interests: All authors have completed and submitted the International Committee of Medical Journal Editors form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.

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., Competing Interests: All authors have completed and submitted the ICMJE form for disclosure of potential conflicts of interest. No potential conflicts of interest were disclosed.

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., (Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2014. This work is written by (a) US Government employee(s) and is in the public domain in the US.)

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., (Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.)

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., (Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.)

Measles and rubella were common infectious diseases in Egypt during the prevaccine era. Monovalent measles vaccine was introduced in 1977, and measles vaccination coverage increased from <50% to >90% from 1980 to 1999; however, measles outbreaks continued to occur at 2- to 4-year intervals during this period. After the introduction of a second routine dose of measles vaccine as a combined measles-mumps-rubella (MMR) vaccine in 1999 and the implementation of measles immunization campaigns targeting 6- to 16-year-old children during 2000-2003, reported measles cases dramatically decreased by 2003. In 2002, Egypt established a goal to eliminate measles and rubella and to prevent congenital rubella syndrome (CRS) by 2010. Large-scale rubella and measles outbreaks in 2005-2007, however, led to a revision of the plan of action to achieve the 2010 goals. A nation-wide measles-rubella immunization campaign, targeting children, adolescents, and young adults 2-20 years old, was conducted in 2 phases during 2008-2009 and achieved coverage >95%. With the decrease to record low levels of cases of measles and rubella in 2009 and 2010, Egypt should achieve measles and rubella elimination in the near future, but high coverage(>95%) with 2 doses of measles-rubella vaccine needs to be maintained, measles-rubella surveillance strengthened, and CRS surveillance developed., (Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.)

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., (Published by Oxford University Press on behalf of the Infectious Diseases Society of America 2011.)

Enterovirus 71 (EV71) (genus Enterovirus, family Picornaviridae), a common cause of hand, foot, and mouth disease (HFMD), may also cause severe neurological diseases, such as encephalitis and poliomyelitis-like paralysis. To examine the genetic diversity and rate of evolution of EV71, we have determined and analyzed complete VP1 sequences (891 nucleotides) for 113 EV71 strains isolated in the United States and five other countries from 1970 to 1998. Nucleotide sequence comparisons demonstrated three distinct EV71 genotypes, designated A, B, and C. The genetic variation within genotypes (12% or fewer nucleotide differences) was less than the variation between genotypes (16.5 to 19.7%). Strains of all three genotypes were at least 94% identical to one another in deduced amino acid sequence. The EV71 prototype strain, BrCr-CA-70, isolated in California in 1970, is the sole member of genotype A. Strains isolated in the United States and Australia during the period from 1972 to 1988, a 1994 Colombian isolate, and isolates from a large HFMD outbreak in Malaysia in 1997 are all members of genotype B. Although strains of genotype B continue to circulate in other parts of the world, none have been isolated in the United States since 1988. Genotype C contains strains isolated in 1985 or later in the United States, Canada, Australia, and the Republic of China. The annual rate of evolution within both the B and C genotypes was estimated to be approximately 1.35 x 10(-2) substitutions per nucleotide and is similar to the rate observed for poliovirus. The results indicate that EV71 is a genetically diverse, rapidly evolving virus. Its worldwide circulation and potential to cause severe disease underscore the need for additional surveillance and improved methods to identify EV71 in human disease.

In 1996, an epidemic of 393 cases of laboratory-confirmed West Nile meningoencephalitis occurred in southeast Romania, with widespread subclinical human infection. Two case-control studies were performed to identify risk factors for acquiring infection and for developing clinical meningoencephalitis after infection. Mosquitoes in the home were associated with infection (reported by 37 [97%] of 38 asymptomatically seropositive persons compared with 36 [72%] of 50 seronegative controls, P<.01) and, among apartment dwellers, flooded basements were a risk factor (reported by 15 [63%] of 24 seropositive persons vs. 11 [30%] of 37 seronegative controls, P=.01). Meningoencephalitis was not associated with hypertension or other underlying medical conditions but was associated with spending more time outdoors (meningoencephalitis patients and asymptomatically seropositive persons spent 8.0 and 3.5 h [medians] outdoors daily, respectively, P<.01). Disease prevention efforts should focus on eliminating peridomestic mosquito breeding sites and reducing peridomestic mosquito exposure.

Between November 1991 and March 1992, 37 cases of paralytic poliomyelitis occurred in Jordan, where none had been reported since 1988. Of these, 17 (50%) of 34 patients had received at least three doses of oral poliovirus vaccine (OPV3). The first and 2 subsequent case-patients were children of Pakistani migrant workers, and the first 8 and a total of 27 (75%) case-patients resided in or near the Jordan Valley. A seroepidemiologic study of 987 children in all regions of Jordan was performed to assess OPV3 coverage and immune response to OPV. Although OPV3 coverage by 12 months of age was high (96%) in the general population, coverage was lower among Pakistani (21%), Bedouin (63%), and Gypsy (9%) children (P < .001). Seroprevalences for poliovirus type 3 were 71% in the Jordan Valley versus 81% in other regions after 3 doses of OPV (P < .06) and 77% in the Jordan Valley versus 98% in other regions after 5 doses of OPV (P < .001). This outbreak demonstrates the importance of achieving high seroimmunity to infection in all geographic areas to prevent the reintroduction and spread of imported strains of wild poliovirus.

Timely investigation of children with acute flaccid paralysis, with collection of stool specimens for virus isolation, is the primary strategy used to detect wild poliovirus circulation. To determine the optimal timing of stool specimen collection, studies of wild and vaccine poliovirus excretion published between 1935 and 1995 were reviewed. Data were compiled from comparable studies, scatter plots of the data were created, and third-order regression lines were calculated. The data indicated that wild polioviruses were excreted by a majority of previously unvaccinated infants and young children for 3-4 weeks. The duration of viral shedding was reduced, however, among children who were previously vaccinated with inactivated poliovirus vaccine, who had preexisting antibodies to the infecting serotype, or who had previous intestinal infection with homologous poliovirus. These data suggest that the 14-day period after onset of paralysis is the interval with the highest probability of detecting wild poliovirus excretion in paralyzed children.

In vaccinated populations, the diagnosis of measles often requires laboratory confirmation. Serum tested by EIAs has proven sensitive and specific for diagnosing measles. For comparison of detection of measles-specific IgM in oral fluid and serum samples by an antibody-capture EIA, 163 Ethiopian infants who presented for routine measles vaccination were studied. Paired serum and oral fluid samples were collected before and 2 weeks after vaccination; 269 paired samples were adequate for analyses. Of the 104 serum samples that were IgM-positive, 95 (91%) of the paired oral fluid samples were IgM-positive. Of the 165 serum samples that were IgM-negative, 156 (95%) of the paired oral fluid samples were IgM-negative. The Pearson partial correlation coefficient for optical density readings from postvaccination oral fluid compared with serum was 0.81. Oral fluid appears to be an acceptable alternative to serum for measuring measles-specific IgM antibodies by an antibody-capture EIA.

Since first described in 1974, enterovirus 71 infections have been associated with severe neurologic disease, and widespread infection was suspected in 1987. To investigate enterovirus 71 activity further, data were reviewed for isolations reported nationally during 1977-1991, virology laboratories were contacted regarding isolations during 1985-1989, and medical records were reviewed for respective patients, 1985-1989. From 1977 to 1991, 193 culture-confirmed enterovirus 71 infections were identified: > or = 1 isolate each year. In 1987, 45 persons in 17 states were infected compared with a maximum of 22 persons in 1-8 states in the other years. Of these 45, 27 (60%) had the following: paralysis (6), Guillain-Barré syndrome (1), meningitis (18), or encephalitis (2). Enterovirus 71 has been endemic in the United States since at least 1977, was identified more frequently in 1987 than in other years, and continues to be an occasional cause of severe neurologic disease.

In an investigation of a school outbreak of enterovirus-like illness and aseptic meningitis, an IgM antibody assay was used to identify persons with evidence of recent coxsackie virus B2 infection. During September and October 1989, 81 (25%) of 319 students and staff reported an enterovirus-like illness; of these, 17 (21%) also had aseptic meningitis. Attack rates for enterovirus-like illness were highest among varsity football team members (53%), and most of this illness occurred between 6 and 15 October. Coxsackie virus B2 was isolated from 2 varsity football players. IgM antibody studies confirmed that coxsackie virus B2 was the cause of the outbreak in the varsity football team and suggested it was not responsible for much of the disease in other students and staff: 63% of football team members were seropositive compared with 12% for other students in grades 6-12. This report illustrates the value of an IgM antibody assay in the investigation of enterovirus outbreaks to distinguish infection from illness.