Maureen Birmingham

Global Mortality Associated with Rotavirus Disease among Children in 2004

BACKGROUND As new rotavirus vaccines are being introduced in immunization programs, global and national estimates of disease burden, especially rotavirus-associated mortality, are needed to assess the potential health benefits of vaccination and to monitor vaccine impact. METHODS We identified 76 studies that were initiated after 1990, lasted at least 1 full year, and examined rotavirus among >100 children hospitalized with diarrhea. The studies were assigned to 5 groups (A-E) with use of World Health Organization classification of countries by child mortality and geography. For each group, the mean rotavirus detection rate was multiplied by diarrhea-related mortality figures from 2004 for countries in that group to yield estimates of rotavirus-associated mortality. RESULTS Overall, rotavirus accounted for 527,000 deaths (95% confidence interval, 475,000-580,000 deaths) annually or 29% of all deaths due to diarrhea among children <5 years of age. Twenty-three percent of deaths due to rotavirus disease occurred in India, and 6 countries (India, Nigeria, Congo, Ethiopia, China, and Pakistan) accounted for more than one-half of deaths due to rotavirus disease. CONCLUSIONS The high mortality associated with rotavirus disease underscores the need for targeted interventions, such as vaccines. To realize the full life-saving potential of vaccines, it will be vital to ensure that they reach children in countries with high mortality. These baseline figures will allow future assessment of vaccine impact on rotavirus-associated mortality.

How best to estimate the global burden of pertussis

In most countries, pertussis surveillance is inadequate for accurately estimating numbers of cases or deaths. Good estimates are needed to help set priorities for vaccination programmes. We aimed to develop a simple, reliable, and explicit method for estimating pertussis cases and deaths for children under 15 years to calculate the global disease burden in 1999. We estimated the proportion of susceptible children becoming infected in countries with poor vaccination coverage (<70%) in 1999 at 30% by 1 year, 80% by 5 years, and 100% by 15 years of age and for countries with good coverage (> or =70%) at 10% by 1 year, 60% by 5 years, and 100% by 15 years. Vaccine efficacy was estimated at 80% for preventing infection and 95% for preventing deaths. We used UN population estimates and vaccination coverage reported to WHO (adjusted for specific survey data if available). Case fatality ratios for countries with high and low child mortality were derived from published and unpublished work. For some countries with good vital events registration we used reported deaths adjusted for underascertainment. In 1999 there were an estimated 48.5 million pertussis cases in children worldwide. Deaths from pertussis were estimated at 390000 and at 295000 after adjustment for local data sources. Based on this approach, disability-adjusted life years from pertussis (12.7 million) in 2000 exceeded those of other preventable diseases such as lung cancer (11.4 million) and meningitis (5.8 million). This simple approach yields estimates that can be used for setting vaccination programme priorities. Better data are needed on the public health importance of pertussis in high mortality countries, the benefits of incomplete vaccination, and the harm from delayed vaccination.

WHO and UNICEF estimates of national infant immunization coverage: methods and processes

WHO and the United Nations Childrens Fund (UNICEF) annually review data on immunization coverage to estimate national coverage with routine service delivery of the following vaccines: bacille Calmette-Guérin; diphtheria-tetanus-pertussis, first and third doses; either oral polio vaccine or inactivated polio vaccine, third dose of either; hepatitis B, third dose; Haemophilus influenzae type b, third dose; and a measles virus-containing vaccine, either for measles alone or in the form of a combination vaccine, one dose. The estimates are based on government reports submitted to WHO and UNICEF and are supplemented by survey results from the published and grey literature. Local experts, primarily national immunization system managers and WHO/UNICEF regional and national staff, are consulted for additional information on the performance of specific immunization systems. Estimates are derived through a country-by-country review of available data informed and constrained by a set of heuristics; no statistical or mathematical models are used. Draft estimates are made, sent to national authorities for review and comment and modified in light of their feedback. While the final estimates may not differ from reported data, they constitute an independent technical assessment by WHO and UNICEF of the performance of national immunization systems. These country-specific estimates, available from 1980 onward, are updated annually.

Estimates of measles case fatality ratios: a comprehensive review of community-based studies.

BACKGROUND Global deaths from measles have decreased notably in past decades, due to both increases in immunization rates and decreases in measles case fatality ratios (CFRs). While some aspects of the reduction in measles mortality can be monitored through increases in immunization coverage, estimating the level of measles deaths (in absolute terms) is problematic, particularly since incidence-based methods of estimation rely on accurate measures of measles CFRs. These ratios vary widely by geographic and epidemiologic context and even within the same community from year-to-year. METHODS To understand better the variations in CFRs, we reviewed community-based studies published between 1980 and 2008 reporting age-specific measles CFRs. RESULTS The results of the search consistently document that measles CFRs are highest in unvaccinated children under age 5 years; in outbreaks; the lowest CFRs occur in vaccinated children regardless of setting. The broad range of case and death definitions, study populations and geography highlight the complexities in extrapolating results for global public health planning. CONCLUSIONS Values for measles CFRs remain imprecise, resulting in continued uncertainty about the actual toll measles exacts.

The Global Burden of Measles in the Year 2000—A Model that Uses Country‐Specific Indicators

The estimation of the global burden of measles is challenging in the absence of reliable and comparable surveillance systems worldwide. A static model is described that enables estimation of measles morbidity, mortality, and disability for the year 2000 on the basis of country-specific information (i.e., demographic profile, vaccine coverage, and estimates of case-fatality ratios). This approach estimated a global incidence of 39.9 million measles cases, 777,000 deaths, and 28 million disability-adjusted life years. The World Health Organization regions of Africa and Southeast Asia had 70% of incident cases and 84% of measles-related deaths; 11 countries alone (Afghanistan, Burkina Faso, Democratic Republic of the Congo, Ethiopia, India, Indonesia, Niger, Nigeria, Pakistan, Somalia, Uganda) account for 66% of deaths. This approach quantifies the measles burden by considering country-specific indicators, which can be updated, permitting an assessment of country, regional, and global changes in the burden associated with measles infection.

The Biologic Principles of Poliovirus Eradication

Abstract The biologic principles for the global eradication of poliomyelitis are as follows: Poliovirus causes acute, nonpersistent infections, virus is transmitted by infectious humans or their waste, survival of virus in the environment is finite, humans are the only reservoir, and immunization with polio vaccine interrupts virus transmission. These principles appear to be sound. The potential for prolonged virus excretion by immunocompromised patients requires further definition, although there is no epidemiologic evidence of a threat to eradication. Survival of poliovirus in the environment is highly variable, but viral inactivation is usually complete within months. Higher primates may be infected with poliovirus, but they are unlikely reservoirs in nature. The only poliovirus reservoir remaining after eradication will be laboratory stocks. Serious attention must be given to reducing this potential source of infection. Polio eradication through immunization is evidenced by the documented absence of poliomyelitis in an increasing number of countries and the progressive disappearance of poliovirus genotypes.

Reemergence of Recombinant Vaccine-Derived Poliovirus Outbreak in Madagascar

BACKGROUND After the 2001-2002 poliomyelitis outbreak due to recombinant vaccine-derived polioviruses (VDPVs) in the Toliara province of Madagascar, another outbreak reoccurred in the same province in 2005. METHODS We conducted epidemiological and virological investigations for each polio case patient and for their contacts. RESULTS From May to August 2005, a total of 5 cases of acute flaccid paralysis were reported among unvaccinated or partially vaccinated children 2-3 years old. Type-3 or type-2 VDPV was isolated from case patients and from healthy contacts. These strains were classified into 4 recombinant lineages that showed complex mosaic genomic structures originating from different vaccine strain serotypes and probably from human enterovirus C (HEV-C) species. Genetic relatedness could be observed among these 4 lineages. Vaccination coverage of the population was very low (<50%). CONCLUSIONS The broad distribution of VDPVs in the province and their close genetic relationship indicate intense and rapid cocirculation and coevolution of the vaccine strains and of their related HEV-C strains. The occurrence of an outbreak due to VDPV 3 years after a previous outbreak indicates that a short period with low vaccination coverage is enough to create favorable conditions for the emergence of VDPV in this setting.

The immunization data quality audit: verifying the quality and consistency of immunization monitoring systems

OBJECTIVE To evaluate the consistency and quality of immunization monitoring systems in 27 countries during 2002-03 using standardized data quality audits (DQAs) that had been launched within the framework of the Global Alliance for Vaccines and Immunization. METHODS The consistency of reporting systems was estimated by determining the proportion of third doses of diphtheria-tetanuspertussis (DTP-3) vaccine reported as being administered that could be verified by written documentation at health facilities and districts. The quality of monitoring systems was measured using quality indices for different components of the monitoring systems. These indices were applied to each level of the health service (health unit, district and national). FINDINGS The proportion of verified DTP-3 doses was lower than 85% in 16 countries. Difficulties in verifying the doses administered often arose at the peripheral level of the health service, usually as the result of discrepancies in information between health units and their corresponding districts or because completed recording forms were not available from health units. All countries had weaknesses in their monitoring systems; these included the inconsistent use of monitoring charts; inadequate monitoring of vaccine stocks, injection supplies and adverse events; unsafe computer practices; and poor monitoring of completeness and timeliness of reporting. CONCLUSION Inconsistencies in immunization data occur in many countries, hampering their ability to manage their immunization programmes. Countries should use these findings to strengthen monitoring systems so that data can reliably guide programme activities. The DQA is an innovative tool that provides a way to independently assess the quality of immunization monitoring systems at all levels of a health service and serves as a point of entry to make improvements. It provides a useful example for other global health initiatives.

Experience in Global Measles Control, 1990–2001

Worldwide during the 1980s remarkable progress was made in controlling measles through increasing routine measles vaccination to nearly 80%. In 2000, an estimated 777,000 measles deaths occurred, of which 452,000 were in the African Region of the World Health Organization (WHO). In 2001, WHO and the United Nations Childrens Fund published a 5-year strategic plan to reduce measles mortality by half by 2005. Strategies include providing a second opportunity for measles immunization to all children through nationwide supplementary immunization activities, increasing routine vaccination coverage, and improving surveillance with laboratory confirmation of suspected measles cases. In 2000, over 100 million children received a dose of measles vaccine through supplementary immunization activities, a number projected to increase during 2002-2005. Current systems for monitoring measles vaccination coverage and disease burden must be improved to accurately assess progress toward measles control goals.

Innovation and participation for healthy public policy: the first National Health Assembly in Thailand.

Aim  This paper aims to describe and disseminate the process and initial outcomes of the first National Health Assembly (NHA) in Thailand, as an innovative example of health policy making.