Measles, rubella, and congenital rubella syndrome--United States and Mexico, 1997-1999

In 1996, the Immunization Working Group of the Mexico-United States Binational Commission was established to enhance coordination of disease surveillance, assure high vaccination coverage in both countries, and hasten the elimination of vaccine-preventable diseases. The United States and Mexico share the Pan American Health Organization (PAHO) goal of measles elimination by 2000. The United States also established a goal of eliminating indigenous rubella and congenital rubella syndrome (CRS) by 2000. This report summarizes the measles and rubella vaccination and surveillance data for the United States and Mexico for 1997-1999.     

Elimination of rubella and congenital rubella syndrome--United States, 1969-2004

In October 2004, CDC convened an independent panel of internationally recognized authorities on public health, infectious disease, and immunization to assess progress toward elimination of rubella and congenital rubella syndrome (CRS) in the United States, a national health objective for 2010. Since rubella vaccine licensure in 1969, substantial declines in rubella and CRS have occurred, and the absence of endemic transmission in the United States is supported by recent data: 1) fewer than 25 reported rubella cases each year since 2001, 2) at least 95% vaccination coverage among school-aged children, 3) estimated 91% population immunity, 4) adequate surveillance to detect rubella outbreaks, and 5) a pattern of virus genotypes consistent with virus originating in other parts of the world. Given the available data, panel members concluded unanimously that rubella is no longer endemic in the United States. This report summarizes the history and accomplishments of the rubella vaccination program in the United States and the Western Hemisphere and the challenges posed by rubella for the future.     

A systematic review of rubella vaccination strategies implemented in the Americas: impact on the incidence and seroprevalence rates of rubella and congenital rubella syndrome

Objective

To evaluate the impact of rubella vaccination strategies on the rates of acquired rubella and congenital rubella syndrome in the Americas.

Methods

We conducted a systematic review of the literature (MEDLINE, PubMed, EMBASE, Cochrane Library, Artemisa Database, LILACS Database, Evidence Portal, VHL-PAHO Portal, Scielo, and Grey-Literature sources) that was published from 1969–2010. We included studies on rubella incidence and seroprevalence rates that were associated with rubella vaccination. The quality of the studies was evaluated according to international guidelines.

Results

A total of 14 studies were identified: 2 clinical trials, 2 cohort studies, 3 transversal studies, 5 ecological studies, and 2 mathematical models. Childhood vaccination reduced the incidence of rubella by 23.6% to 99.6%, increased the occurrence of epidemic cycles in Argentina and in the United States, and shifted the illness to susceptible adults. Vaccination strategies that focused on women and children in Brazil were associated with a 5.5-fold greater incidence of rubella in men leading to new outbreaks and CRS. A combined vaccination strategy with a universal approach that included routine vaccination for boys, girls, women, and men in Mexico and in Costa Rica reduced the incidence of rubella by more than 98% and led to absence of CRS since 2008. A medium and a low risk of bias were found in 3 and 4 articles, respectively.

Conclusion

The results of this review demonstrate that the combined vaccination strategy with a universal approach was the most effective strategy as evidenced by a drastic reduction in the number of cases and the interruption of endemic transmission of rubella in the Americas.     

An epidemiological assessment towards elimination of rubella and congenital rubella syndrome in Singapore

ObjectiveIn line with regional and global goals for the elimination of rubella and congenital rubella syndrome (CRS), we reviewed the epidemiological situation in Singapore, based on surveillance reports on rubella and CRS, national immunization coverage and seroprevalence surveys. The aim of our review was to identify current gaps and steps taken to achieve the targets set by the World Health Organization (WHO) Western Pacific Regional Office (WPRO).MethodsEpidemiological data on clinical and laboratory-confirmed rubella cases, including CRS, notified to the Communicable Diseases Division, Ministry of Health, Singapore, from 2003 to 2013 were collated and analyzed. Vaccination coverage against rubella was obtained from the National Immunization Registry and School Health Services of the Health Promotion Board. The changing prevalence of rubella was determined from periodic serological surveys.FindingsThe incidence of indigenous rubella cases per million population decreased from 37.2 in 2008 to 7.6 in 2013 and there had been no indigenous case of CRS in 2012 and 2013. Therapeutic abortions performed due to rubella infections had become uncommon. The annual measles, mumps, and rubella (MMR) vaccination coverage in childhood population remained high ranging from 93% to 96%. The overall susceptibility to rubella in women aged 18–44 years had reduced significantly from 15.8% in 2004 to 11.0% in 2010. The prevalence of IgG antibody against rubella among Singapore children aged 1–17 years was maintained at 87.3% in 2008–2010.ConclusionAll available data indicated that Singapore has made good progress towards the elimination of rubella and CRS. It has attained the targets set by the WHO WPRO for 2015. In preparation for verification of rubella elimination, an enhanced surveillance system has been implemented to ensure that all reported cases are laboratory confirmed, and genotyping of rubella virus strains isolated is carried out to provide evidence for interruption of endemic transmission.     

Control of rubella and congenital rubella syndrome (CRS) in developing countries, Part 2: Vaccination against rubella.

In 1995-96 we conducted a review of rubella immunization strategies. Worldwide, 78 countries (more than one-third) reported a national policy of using rubella vaccine. This was closely related to country economic status. Based on the United Nations country classification, rubella vaccine is used in 92% of industrialized countries, 36% of those with economies-in-transition, and 28% of developing countries. Cases of congenital rubella syndrome (CRS) may be prevented as follows: by providing direct protection to women and/or schoolgirls (a selective vaccination strategy); by vaccinating boys and girls to provide indirect protection by reducing the transmission of rubella virus (a childhood vaccination strategy); or by a combination of these approaches (a combined strategy). A combined strategy was most commonly reported (60% of countries); seven countries (9%) reported a selective strategy; and 24 countries (31%) reported only childhood immunization. Experience has shown that it is essential to include vaccination of women of childbearing age in any rubella control strategy. Childhood vaccination alone may pose a risk of an increase in CRS cases. Although many countries have introduced rubella vaccine, few report any data on the impact of vaccination. Countries using rubella vaccine need to establish surveillance for rubella and CRS and monitor coverage in each of the target groups.     

Strategies to eradicate rubella in the English-speaking Caribbean

OBJECTIVE: This report presents the strategies used to eradicate rubella in the Caribbean region and the challenges faced by that effort. METHODS: Using the surveillance system for measles cases that was instituted in all countries in the Caribbean Community (CARICOM), 12 countries confirmed cases of rubella between 1992 and 1996. Rubella infections occurred in epidemic proportions in 6 countries during that period. RESULTS: On the basis of the rubella prevalence data, rubella-congenital rubella syndrome (CRS) cost-benefit analysis, and cost-effectiveness of the mass campaign, the Council for Human and Social Development of CARICOM resolved, on April 21, 1998, that every effort would be made to eradicate rubella, as well as to prevent the occurrence of new cases of CRS by the end of 2000. Using the Pan American Health Organization's template for measles eradication, CARICOM proposed and implemented the main strategies for rubella and CRS eradication, and rubella mass campaigns were conducted in 18 countries. The target population, which included males and females (aged 20-40 years), was approximately 2.2 million. CONCLUSION: The major challenges for rubella eradication are attaining high vaccine coverage in the adult population and maintaining an effective surveillance system able to detect rubella activity.     

Global Measles and Rubella Laboratory Network, January 2004-June 2005

Measles continues to be a leading cause of childhood morbidity and mortality in developing countries and an outbreak threat in the majority of countries. In 2000, measles was considered the fifth leading cause of childhood mortality, and the World Health Organization (WHO) estimated that approximately 777,000 measles-associated deaths occurred worldwide. In 2001, WHO and the United Nations Children's Fund (UNICEF) developed a 5-year strategic plan, endorsed by the World Health Assembly in 2003, to reduce measles mortality by 50% by 2005 (relative to 1999 estimates) and to achieve and maintain interruption of indigenous measles transmission in large geographic areas with established measles elimination goals. This plan included strengthening routine vaccination coverage, providing a second opportunity for measles immunization to children, improving measles case management, and improving surveillance with laboratory confirmation of suspected measles cases. To date, four of six WHO regions have established measles elimination targets: the Americas Region (AMR) by 2000, the European Region (EUR) by 2010, the Eastern Mediterranean Region (EMR) by 2010, and the Western Pacific Region (WPR) by 2012. The remaining two WHO regions, the African (AFR) and South East Asian (SEAR) regions, are continuing work toward the measles mortality reduction goal. Likewise, to reduce the burden of disease from congenital rubella syndrome (CRS), currently estimated at 100,000 cases per year worldwide, several countries have developed or continue to develop rubella control programs, and AMR and EUR have established regional rubella elimination and CRS reduction goals, respectively. Because improved global surveillance is essential for monitoring progress toward mortality reduction and elimination of these diseases, WHO established the Measles and Rubella Laboratory Network (LabNet) in 2003 to promote case identification and confirmation. This report provides an update on the development of LabNet during January 2004-June 2005 and describes the geographic distribution of measles and rubella virus genotypes as of June 2005.     

Progress and challenges in measles and rubella elimination in the WHO European Region

IntroductionDespite availability of safe and cost-effective vaccines to prevent it, measles remains one of the significant causes of death among children under five years of age globally. The World Health Organization (WHO) European Region has seen a drastic decline in measles and rubella cases in recent years, and a few of the once common measles genotypes are no longer detected. Buoyed by this success, all Member States of the Region reconfirmed their commitment in 2010 to eliminating measles and rubella, and made this a central objective of the European Vaccine Action Plan 2015–2020 (EVAP). Nevertheless, sporadic outbreaks continue, recently affecting primarily adolescents and young adults with no vaccination or an incomplete vaccination history. The European Regional Verification Commission for Measles and Rubella Elimination was established in 2011 to evaluate the status of measles and rubella elimination based on documentation submitted annually by each country’s national verification committee.DiscussionEach country’s commitment to eliminate measles and rubella is influenced by competing health priorities, and in some cases lack of capacity and resources. All countries need to improve case-base surveillance for both measles and rubella, ensure documentation of each outbreak and strengthen the link between epidemiology and laboratory data. Achieving high coverage with measles- and rubella-containing vaccines will require a multisectoral approach to address the root causes of lower uptake in identified communities including service delivery challenges or vaccine safety concerns caused by circulating myths about vaccination.ConclusionsThe WHO European Region has made steady progress towards eliminating measles and rubella and over half of the countries interrupted endemic transmission of both diseases by 2015. The programmatic challenges in disease surveillance, vaccination service delivery and communication in the remaining endemic countries should be addressed through periodic evaluation of the strategies by all stakeholders and exploring additional opportunities to accelerate the ongoing elimination activities.     

Surveillance of congenital rubella and rubella infections in pregnancy in EU/EEA countries, 2012: Current status and future perspective to monitor elimination

IntroductionRubella elimination and congenital rubella syndrome (CRS) prevention are targets for achievement by 2015 in the WHO-EURO Region. This paper describes the existing surveillance systems for CRS and rubella in pregnancy in order to critically interpret the findings in relation to the 2012 WHO-EURO surveillance guidelines.MethodsIn 2012 we conducted a survey to collect information on surveillance of CRS and rubella in pregnancy in 29 EU/EEA countries. Questionnaires explored the characteristics of the surveillance systems, case definition, epidemiological investigation and follow-up of cases, reference laboratories and types of tests performed.ResultsTwenty-eight countries had surveillance systems for CRS, mostly nationwide, mandatory, passive and case-based; 23 collected information on the origin of the infection; 11 reported asymptomatic infections; 6 required zero-reporting. Case definitions varied among countries, although 24 used the EU definition. Laboratories reported cases in 18 countries. Twenty countries collected information on pregnancy within the rubella surveillance system and 5 had specific surveillance for rubella in pregnancy. Two countries did not monitor outcomes of suspected infections in pregnancy; infants with CRS were monitored in all the remaining countries; asymptomatic infected infants in 15; stillbirths and fetal deaths in 13; therapeutic and spontaneous abortions in 8 and 7. Twenty-seven countries had a national reference laboratory for CRS and rubella in pregnancy; genotyping was performed in 15.DiscussionThe current surveillance systems allow adequate CRS monitoring in EU. Further efforts are needed to improve their quality, including uniform case definitions, collection of information on the origin of infection, and promotion of reporting from laboratories. Follow-up of pregnant women with suspected infection should be strengthened because it is an entry point for CRS, including detection of fetal deaths, stillbirths and abortions. Laboratory capacity for confirming congenital rubella infections and infections in pregnancy is good in EU, however the use of genotyping should be encouraged.     

Rubella elimination and improving health care for women

In the Americas, the Pan American Health Organization supports strategies for the appropriate control and elimination of vaccine-preventable diseases, especially if the strategies are designed to reduce health inequities, strengthen the political commitment for immunization services, and promote the culture of prevention. In September 2003, the 44th Directing Council of the Pan American Health Organization adopted a goal to eliminate rubella and congenital rubella syndrome by 2010. One of the main objectives of this initiative is improving women's health, consistent with achieving the Millennium Development Goals. An important component of rubella elimination is conducting vaccination campaigns for men and women of childbearing age to reduce rapidly the number of people susceptible to rubella infection. From 1998 to 2002, the English-speaking Caribbean, Chile, Costa Rica, Brazil, and Honduras conducted mass rubella vaccination campaigns aimed at adults. Vaccination coverage reached > 95% in each country with an exception of the Caribbean, where the coverage was 80%.     

Models of strategies for control of rubella and congenital rubella syndrome—A 40 year experience from Australia

We investigated the impact of vaccination on rubella epidemiology in Australia, using a mathematical model fitted to Australian serosurvey data and incorporating pre-vaccination European estimates of rubella transmissibility. Mass infant measles–mumps–rubella (MMR) vaccination produced a 99% reduction in both rubella and congenital rubella syndrome (CRS) incidence by 2010 compared to the pre-vaccination era (1960–70). The model is consistent with reductions in CRS based on surveillance of congenital hearing impairment. Model simulations suggest that selective schoolgirl vaccination (1971–88) was associated with a 90% reduction in CRS incidence, but only a 1–4% reduction in rubella incidence. Our model predicted that these reductions in rubella were much less vulnerable to reductions in MMR vaccine coverage than for measles. In the future, a less than 15% decrease in MMR vaccine coverage is estimated to have minimal impact before 2060, but a 20% reduction may result in a 7-fold increase in rubella incidence, with the effective reproductive number R rising from 0.28 to 0.78 by 2060. The 99% reduction in both rubella and CRS incidence and low effective reproductive number (R ≤ 0.28) we documented after 2010 are consistent with Australia having achieved rubella elimination.     

Surveillance for congenital rubella in Australia since 1993: Cases reported between 2004 and 2013

Objective

To describe the epidemiology of congenital rubella infections notified to the Australian Paediatric Surveillance Unit (APSU) from 2004 to 2013 and compare that with previously published APSU data for 1993–2003.

Methods

Active national surveillance for congenital rubella infection has been conducted through the APSU since 1993. Monthly reporting by child health clinicians according to pre-defined case criteria triggers requests for clinicians to provide de-identified clinical, epidemiological, and laboratory information. Data were extracted for cases reported between January 2004 and December 2013 and compared with previous years.

Results

Five cases of confirmed congenital rubella infection were identified during the reporting period. All five infants had defects consistent with congenital rubella syndrome (CRS). Four of the infants were born in Australia during the study period, and all were born to mothers born overseas. Three of the five mothers had not had rubella vaccination, and in two vaccination status was unknown, although both were from countries without routine rubella immunization programmes. Since 1993, there have been 57 notifications of congenital rubella infection to the APSU; 40 of these infants were born between January 1993 and December 2013, of whom 34 had confirmed CRS.

Conclusions

Congenital rubella infection in Australia is predominantly among children born to unimmunized immigrant mothers. Migrant women born in rubella endemic countries without routine immunization remain an important group to target for vaccination. Rubella-susceptible women, especially those in the early stages of pregnancy, should also carefully consider the risks of travelling to rubella endemic countries.     

Accelerated rubella control and the prevention of congenital rubella syndrome]

Congenital rubella syndrome (CRS) is associated with substantial morbidity and mortality and with high costs. Today, as a result of improved vaccination and epidemiological surveillance efforts directed at eradicating measles from the Western Hemisphere, there has been a notable increase in the ability to detect, prevent, and control rubella and CRS. The importance of these measures is undeniable, and this piece examines the components that are essential in moving ahead to reduce these major public health problems in Latin America and the Caribbean. One step in that direction would be to integrate the surveillance of measles with that of rubella and CRS.     

Measles eradication: experience in the Americas

In 1994, the Ministers of Health from the Region of the Americas targeted measles for eradication from the Western Hemisphere by the year 2000. To achieve this goal, the Pan American Health Organization (PAHO) developed an enhanced measles eradication strategy. First, a one-time-only "catch-up" measles vaccination campaign is conducted among children aged 9 months to 14 years. Efforts are then made to vaccinate through routine health services ("keep-up") at least 95% of each newborn cohort at 12 months of age. Finally, to assure high population immunity among preschool-aged children, indiscriminate "follow-up" measles vaccination campaigns are conducted approximately every 4 years. These vaccination activities are accompanied by improvements in measles surveillance, including the laboratory testing of suspected measles cases. The implementation of the PAHO strategy has resulted in a marked reduction in measles incidence in all countries of the Americas. Indeed, in 1996 the all-time regional record low of 2109 measles cases was reported. There was a relative resurgence of measles in 1997 with over 20,000 cases, due to a large measles outbreak among infants, preschool-aged children and young adults in S?o Paulo, Brazil. Contributing factors for this outbreak included: low routine infant vaccination coverage, failure to conduct a "follow-up" campaign, presence of susceptible young adults, and the importation of measles virus, apparently from Europe. PAHO's strategy has been effective in interrupting measles virus circulation. This experience demonstrates that global measles eradication is an achievable goal using currently available measles vaccines.     

Rubella and congenital rubella syndrome: global update.

Worldwide, it is estimated that there are more than 100.000 infants born with congenital rubella syndrome (CRS) each year. In 1998, standard case definitions for surveillance of CRS and rubella were developed by the World Health Organization (WHO). In 2001, 123 countries/territories reported a total of 836.356 rubella cases. In the future more countries are expected to report on rubella as a global measles/rubella laboratory network is further developed under the coordination of WHO. Operational research is being conducted to improve rubella surveillance. This includes projects on initiating CRS surveillance, comparative studies on diagnostic laboratory methods, and molecular epidemiology research to expand the global understanding of patterns of rubella virus circulation. In 1996 a WHO survey found that 78 od 214 reporting countries/territories (36%) were using rubella vaccine in their routine immunization services. By the en of 2002 a total of 124 of the 214 counties/territories (58%) were using rubella vaccine. Rubella vaccine use varies by stage of economic development: 100% for industrialized countries, 71% for countries with economies in transition, and 48% for developing countries. A safe effective rubella vaccine is available, and there are proven vaccination strategies for preventing rubella and CRS. A WHO position paper provides guidance on programmatic aspects of rubella vaccine introduction. The introduction of rubella vaccine is cost-effective and cost-beneficial but requires ongoing strengthening of routine immunization services and surveillance systems.     

Fortschritte bei der Eliminierung von Masern und Röteln in der Europäischen Region der WHO

Substantial progress has been made in the World Health Organization (WHO) European Region toward reaching the goal of measles and rubella elimination. We analyzed the surveillance data of 2012 on measles and rubella for agegroup, diagnosis confirmation status (clinical, laboratory-confirmed and epidemiologically linked), vaccination status, and measles-related deaths. For 2012, there were 23,871 measles cases and 29,361 rubella cases reported in the region, mostly among unvaccinated persons. Almost one in three patients with measles and one in five patients with rubellawere aged 20 years and older. In a few countries, widespread outbreaks or indigenous transmission of measles persisted in 2012. While most countries in the region have controlled rubella, a small number still reported a high incidence and several outbreaks. Therefore, more efforts are required to achieve the goal of eliminating measles and rubella in the WHO European Region by 2015, particularly in high-incidence countries. The WHO measles and rubella elimination plan stipulates that all countries should achieve and maintain the required high vaccination coverage while conducting high-quality surveillance.     

Modelling the incidence of congenital rubella syndrome in developing countries

BACKGROUND: As of 1997, less than one-third of developing countries included rubella vaccine in their national immunization programme. In countries that have achieved high coverage of measles vaccine, an ideal opportunity exists to include control of rubella and congenital rubella syndrome (CRS) in enhanced measles control activities. Data on the burden of congenital rubella syndrome are important to guide rubella vaccination policies. METHODS: We reviewed the literature to identify studies of rubella antibody prevalence in developing countries that were conducted on populations with no major selection bias, prior to wide-scale rubella vaccination in the country. We used a simple catalytic model to describe the age-specific prevalence of susceptibility to rubella virus infection in given populations. Estimates of the incidence of infection among pregnant women were calculated using expressions for the average prevalence of susceptibility to infection and the incidence of infection during gestation. To estimate the number of cases of CRS, we assumed an overall risk of 65% after infection in the first 16 weeks of pregnancy and zero risk thereafter. These estimates were derived for each country for which data were available, then for each World Health Organization region, excluding Europe. RESULTS: The estimated mean incidence of CRS per 100,000 live births was lowest in the Eastern Mediterranean region (77.4, range 0-212) and highest in the Americas (175, range 0-598). The mean of the estimates of the total number of cases of CRS in developing countries in 1996 was approximately 110,000. The range was, however, very wide, from as few as 14,000 to as many as 308,000 cases. CONCLUSIONS: Congenital rubella syndrome is an under-recognized public health problem in many developing countries. There is an urgent need for collection of appropriate data to estimate the cost-effectiveness of a potential global rubella control programme.     

Modelling rubella in Europe

The prevention of congenital rubella syndrome (CRS), as a complication of rubella infection during pregnancy, is the main aim of rubella vaccination programmes. However, as vaccination of infants leads to an increase in the average age at which those who were not immunized become infected, certain rubella vaccination programmes can lead to an increase in the incidence of CRS. In this paper we use a mathematical model of the transmission dynamics of rubella virus to investigate the likely impact of different vaccination policies in Europe. The model was able to capture pre- and post-vaccination patterns of infection and prevalence of serological markers under a wide variety of scenarios, suggesting that the model structure and parameter estimates were appropriate. Analytical and numerical results suggest that endemic circulation of rubella is unlikely in Finland, the United Kingdom, The Netherlands, and perhaps Denmark, provided vaccine coverage is uniform across geographical and social groups. In Italy and Germany vaccine coverage in infancy has not been sufficient to interrupt rubella transmission, and continued epidemics of CRS seem probable. It seems unlikely that the immunization programmes in these countries are doing more harm than good, but this may be partly as a result of selective immunization of schoolgirls. Indeed, in both these countries, selective vaccination of schoolgirls with inadequate vaccination histories is likely to be an important mechanism by which CRS incidence is suppressed (unlike the other countries, which have had sufficiently high infant coverage rates to withdraw this option). Reducing inequalities in the uptake of rubella vaccine may bring greater health benefits than increasing the mean level of coverage.     

Reducing global disease burden of measles and rubella: report of the WHO Steering Committee on research related to measles and rubella vaccines and vaccination, 2005

The WHO Steering Committee reviewed and evaluated the progress towards global control of measles and rubella and provided guidelines for future research activities concerning both diseases during its meeting in New Delhi, in April 2005. Global measles vaccination coverage increased from 71% in 1999 to 76% in 2004 and indigenous transmission was interrupted or kept at very low levels in many countries. However, Africa and Southeast Asia continue to experience endemic transmission and high mortality rates, despite a global mortality reduction of 39% between 1999 and 2003. On the basis of reports from countries with continued indigenous measles virus transmission, future control strategies as well as advantages and potential drawbacks of global measles eradication were discussed. Similarly the burden of rubella and congenital rubella syndrome (CRS) as well as the cost-effectiveness of rubella vaccination was assessed using different methods in several countries without vaccination programs. As measles and rubella viruses continue to circulate surveillance and control strategies need further optimization. RT-PCR was considered as an alternative method for laboratory diagnosis of CRS. The value of dried blood spots and oral fluid as alternative samples for measles and rubella IgG and IgM detection and genotype determination was evaluated. However further validation of these methods in different settings is required before their routine use can be recommended.     

Control of rubella and congenital rubella syndrome (CRS) in developing countries, Part 1: Burden of disease from CRS.

Congenital rubella syndrome (CRS) can lead to deafness, heart disease, and cataracts, and a variety of other permanent manifestations. In developing countries, the burden of CRS has been assessed as follows: by surveillance of CRS; by surveillance of acquired rubella; by age-stratified serosurveys; and by serosurveys documenting the rubella susceptibility of women of childbearing age. During rubella outbreaks, rates of CRS per 1000 live births were at least 1.7 in Israel, 1.7 in Jamaica, 0.7 in Oman, 2.2 in Panama, 1.5 in Singapore, 0.9 in Sri Lanka, and 0.6 in Trinidad and Tobago. These rates are similar to those reported from industrialized countries during the pre-vaccine era. Special studies of CRS have been reported from all WHO regions. Rubella surveillance data show that epidemics occur every 4-7 years, similar to the situation in Europe during the pre-vaccination era. In developing countries, the estimated average age at infection varies from 2-3 years to 8 years. For 45 developing countries we identified serosurveys of women of childbearing age that had enrolled > or = 100 individuals. The proportion of women who remained susceptible to rubella (e.g. seronegative) was < 10% in 13 countries. 10-24% in 20 countries, and > or = 25% in 12 countries. Discussed are methods to improve the surveillance of rubella and CRS in developing countries.