Immunogenicity of a locally produced hepatitis B vaccine with the birth dose stored outside the cold chain in rural Vietnam.

The heat stability of hepatitis B vaccine (HepB vaccine) should enable its storage outside the cold chain (OCC), increasing access to the birth dose in areas lacking refrigeration. We compared the immunogenicity of a locally produced vaccine among infants who received three doses stored within the cold chain (n = 358) or for whom the first dose was stored OCC for up to one month (n = 748). Serum was collected from these infants at age 9-18 months. The vaccine was protective in 80.3% of all infants. There were no differences in the prevalence of a protective level of antibody or antibody titer among groups of infants according to storage strategy. Differences in antibody titer between certain groups of infants could be explained by different vaccination schedules. Where birth dose coverage will be improved, HepB vaccine can be taken OCC for up to one month without affecting its immunogenicity.

Hepatitis B infection in rural Vietnam and the implications for a national program of infant immunization.

To ascertain hepatitis B virus (HBV) infection rates for Vietnam, we surveyed HBV markers in two districts of Thanh Hoa province. We randomly selected 536 infants (9- < or = 18 months old), 228 children (4 to < or = 6 years old), 219 adolescents (14 to < or = 16 years old), and 596 adults (25 to < or = 40 years old). On questioning, none of those surveyed had received vaccine against HBV. Hepatitis B virus surface antigen (HBsAg) and total HBV core antibody (anti-HBc) were measured in all specimens, and HBV e antigen (HBeAg) in those positive for HBsAg, and HBV surface antibody (anti-HBs) were measured in all others. Current infection (HBsAg+) rates were infants = 12.5%, children = 18.4%, adolescents = 20.5%, and adults = 18.8%. Current or previous infection (HBsAg+, anti-HBc+, or anti-HBs+) increased with age (infants = 19.6%, children = 36.4%, adolescents = 55.3%, adults = 79.2%). Rates of HBeAg among those HBsAg+ were infants = 85.1%, children = 88.1%, adolescents = 71.1%, and adults = 30.4%. The epidemiology of HBV in Vietnam resembles that of many southeast Asian nations before introduction of vaccine. Immunization of newborns will have enormous impact on HBV-related morbidity and mortality there.

Improving birth dose coverage of hepatitis B vaccine.

Administration of a birth dose of hepatitis B vaccine (HepB vaccine) to neonates is recommended to prevent mother-to-infant transmission and chronic infection with the hepatitis B virus (HBV). Although manufacturers recommend HepB vaccine distribution and storage at 2-8 degrees C, recognition of the heat stability of hepatitis B surface antigen stimulated research into its use after storage at, or exposure to, ambient or high temperatures. Storage of HepB vaccine at ambient temperatures would enable birth dosing for neonates delivered at home in remote areas or at health posts lacking refrigeration. This article reviews the current evidence on the thermostability of HepB vaccine when stored outside the cold chain (OCC). The reports reviewed show that the vaccines studied were safe and effective whether stored cold or OCC. Field and laboratory data also verifies the retained potency of the vaccine after exposure to heat. The attachment of a highly stable variety of a vaccine vial monitor (measuring cumulative exposure to heat) on many HepB vaccines strongly supports policies allowing their storage OCC, when this will benefit birth dose coverage. We recommend that this strategy be introduced to improve birth dose coverage, especially in rural and remote areas. Concurrent monitoring and evaluation should be undertaken to affirm the safe implementation of this strategy, and assess its cost, feasibility and effect on reducing HBV infection rates. Meanwhile, release of manufacturer data verifying the potency of currently available HepB vaccines after exposure to heat will increase confidence in the use of vaccine vial monitors as a managerial tool during storage of HepB vaccine OCC.

Comparative evaluation of a combined DTP-HB vaccine in the EPI in Chiangrai Province, Thailand.

Combined vaccines have been advocated as an efficient method of paediatric vaccine delivery. This study examined the performance and cost implications for the use of combined DTP-HB vaccine in the Thai immunisation program. Separate DTP and HB and then combined DTP-HB vaccines were used in the infant immunisation program in Chiangrai Province during a 4-year period. DTP vaccination coverage was maintained with the combined vaccine and HB coverage was improved (95.7% for DTP-HB1, 95.2% for DTP-HB2 and 93.8% for DTP-HB3). Seroconversion rates for anti-HBs rose from a baseline of 88.4 to 94.8% with use of the combined vaccine. Seroconversion rates for anti-D (97.5%) and anti-P (89.6%) were higher in the separate vaccine regimen. Although this study was not able to demonstrate that DTP-HB vaccine was more cost saving than the vaccines given separately as baseline vaccine coverage was already high, in settings where coverage rates are much lower the increased cost of combined vaccines may be more justifiable.

Prospective population-based incidence of Haemophilus influenzae type b meningitis in Thailand.

There are limited prospective data for Haemophilus influenzae type b (Hib) disease in Asia, where some countries are considering vaccine introduction. A prospective population-based study was conducted to measure the incidence of Hib meningitis in children in two northern provinces of Thailand. Children <5 years with symptoms consistent with bacterial meningitis were enrolled in the study if inclusion criteria were met. The study enrolled 598 children with clinical meningitis, 76% of whom received lumbar puncture. The rate of probable bacterial meningitis was 26.6/100,000 children <5 years per year. There were four cases of laboratory confirmed Hib meningitis (rate 3.8/100,000 children <5 years per year). These findings suggest a relatively low incidence of Hib meningitis. However, additional data from studies of pneumonia are needed to define the Hib disease burden in Thailand.

La hepatitis en las Américas : informe del grupo colaborador de la OPS / Hepatitis in the Americas: report of the PAHO collaborating group

Viral hepatitis is a major public health problem throughout the Americas. Each of the several types of hepatitis (A, B, delta, non-A non B) causes significant morbidity and mortality in the Region. Hepatitis B (HB) infection, now a vaccine-preventable disease, requires the most urgent attention at this time. HB infection endemicity in the Region varies from low (temperate North and South America) to moderate (Tropical Central and South America), but high HBV endemicity occurs throughout the Amazon Basin, in Hispaniola, and in certain population of several other tropical countries. Factors such as race, socioeconomic status, and urban-rural status as well as lifestyle (homosexuality, prostitution) and occupational (health care) factors increase HB prevalence in segments of populations, and it is likely that the number of persons at high risk of HB infection is currently underestimated. Chronic consequences of HB infection are likely proportional to disease endemicity and, in high endemicity areas, comparable to those in Africa and Southeast Asia. In addition, delta infection causes high mortality due to fulminant and chronic hepatitis throughout the high HBV endemicity areas in northern South America. Hepatitis A is a disease of childhood throughout the Region, and causes significant morbidity in older children

Características serológicas y epidemiológicas de la hepatitis vírica aguda en la cuenca Amazónica del Brasil / Serologic and epidemiologic characteristics of acute viral hepatitis in the Amazon Basin of Brazil

From June 1979 to December 1984 a study was made of the frequency and causes of acute hepatitis, including the fulminant form, in Boca do Acre municipality, in the extreme southwestern corner of the Amazon Basin of Brazil. Serologic studies were done by the radioimmunoassay and enzyme immunoassay techniques. Earlier studies of serologic prevalence had indicated that hepatitis Aand hepatitis B were highly endemic throughout the region and that most people were infected during the first ten years of life. Hepatitis A caused 37 per cent of reported cases; it was the predominant type among children over 5 years of age and produced an epidemic pattern. Hepatitis B accounted for 48 per cent of the cases and was a leading cause of disease in both children and adults. Non-A, non-B hepatitis was encountered chiefly in older adults. The incidence of acute and fulminant hepatitis was 3.33 and 0.365 cases per 1 000 persons/year, respectively. In more than 85 per cent of the cases of fulminant hepatitis there was an active hepatitis B virus infection (HBV) and patient sera tested positive for the hepatitis B surface antigen (HBsAg). The most frequent single cause of fulminant hepatitis was superinfection by delta virus of carriers of HBV. The rates of fulminant acute hepatitis found in Boca do Acre are considerably higher than those reported previously in other parts of Brazil or of the Americas

La hepatitis en las Americas: informe del grupo colaborador de la OPS / Hepatitis in the Americas: report of the PAHO collaborating group

La hepatitis vírica es uno de los principales problemas de salud pública en todas partes de las Américas. Todos los tipos de hepatitis (A, B, delta, no-A, no-B) son causas importantes de morbilidad y mortalidad en la Región. La infección por el virus de la hepatitis B (VHB), actualmente prevenible mediante vacunación, requiere atención inmediata. La endemicidad de esta infección varía de baja (en zonas templadas de América del Norte y América del Sur) a moderada (en zonas tropicales de América Central y América del Sur), pero es muy alta en toda la cuenca del Amazonas, en La Española y en ciertas poblaciones de otros países tropicales. La prevalencia de VHB en grupos de población aumenta conforme a ciertos factores como raza, condición socioeconómica, ambiente urbano o rural, estilo de vida (homosexualidad, prostitución) y factores ocupacionales (servicios de salud), y es posible que se haya subestimado el número de habitantes actualmente en alto riesgo de contraer la infección. Es probable que las consecuencias crónicas de la infección por VHB se relacionen proporcionalmente con la endemicidad y que las zonas más endémicas sean comparables a las de Africa y Asia Sudoriental. Además, la infección delta causa alta mortalidad por hepatitis fulminante y crónica en las zonas de alta endemicidad en el norte de América del Sur. La hepatitis A en la Región es una enfermedad de la niñez y produce altas tasas de morbilidad entre los niños mayores. En los adultos, otra causa importante de morbilidad es la hepatitis no-A, no-B; los tipos de esta hepatitis que se transmiten a través de la sangre existen en todas partes de la Región, pero será necesario realizar estudios adicionales para confirmar la presencia del tipo entérico o epidémico. El control de la infección por hepatitis merece alta prioridad en la Región. Deben dedicarse esfuerzos especiales a la producción de reactivos diagnósticos de bajo costo y al fortalecimiento de los programas de laboratorio...

Características serológicas y epidemiológicas de la hepatitis vírica aguda en la cuenca amazónica del Brasil / Serologic and epidemiologic characteristics of acute viral hepatitis in the Amazon Brasin of Brazil

Durante el período de junio de 1979 a diciembre de 1984 se estudiaron la frecuencia y las causas de la hepatitis aguda, incluida la fulminante, en el municipio de Boca do Acre, localizado en el extremo sudoccidental del Amazonas brasileiro. Se hicieron estudios serológicos por medio de las técnicas de radioinmunoensayo y ensayo inmunoenzimático. Los estudios previos de prevalencia serológica indicaron que la hepatitis A y la hepatitis B eran muy endémicas en toda la región y que la mayoría de las personas contraían la infección en los primeros 10 años de vida. La hepatitis A causó el 37% de todos los casos notificados, fue el tipo predeominante entre los niños mayores de cinco años y produjo un patrón epidémico. La hepatitis B constituyó el 48% de los casos y fue una causa importante de enfermedad tanto en los niños como en los adultos. La hepatitis no-A, no-B se presentó principalmente en adultos mayores. La incidencia de las hepatitis aguda y fulminante fue de 3,33 y 0,365 casos anuales por cada 1.000 habitantes, respectivamente. En más de 85% de los casos de hepatitis fulminante existía infección activa por el virus de la hepatitis B (VHB) y los sueros de los pacientes daban resultados positivos respecto al antígeno de superficie de la hepatitis B (AgsHB). la causa individual más frecuente de hepatitis fulminante fue la superinfección por virus delta de portadores del VHB. Las tasas de hepatitis aguda fulminante halladas en Boca do Acre son considerablemente mayores que las informadas con anterioridad en el continente americano y en otras partes del Brasil. Si bien la hepatitis A y la hepatitis B son causas importantes de hepatitis aguda, la infección combinada por virus delta y VHB es la causa principal del tipo poco común de hepatitis fulminante encontrado en la región estudiada