|TAG Recommendations for Hepatitis Vaccine|
Every two years the Technical Advisory Group (TAG) meets to discuss the achievements of the countries in the Region, as well as new challenges for continued protection of their populations. At the end of the meeting the group submit recommendations to address current and future challenges for immunization programs in the Americas. Below you will find the recommendations for hepatitis vaccine:
Tremendous progress has been made in the prevention of hepatitis B related morbidity and mortality globally. The WHO last revised its position with respect to hepatitis B vaccines in 2009. In this document, the use of the birth dose (hepatitis B vaccine within 24 hours of birth) was recommended for all countries. Countries were also encouraged to develop goals for hepatitis B control. Prior to that, the SAGE hepatitis B working group presented information on feasibility for the elimination of hepatitis B virus (HBV) transmission; however, SAGE chose a controlled approach. Despite this global approach, a number of countries have adopted elimination strategies, including Cuba and the United States. Much has been published on the feasibility of this approach. Clear definitions of elimination have not been developed; however, a recent PAHO mission to Cuba showed that this can be best described by data on protected birth cohorts. In Cuba, by 2010, the majority of persons born in the previous 30 years have been protected with high coverage of hepatitis B vaccines. The impact of vaccine delivery is important to document. .
It has been estimated that as many as 400,000 new hepatitis B infections occur annually in the Americas. In highly endemic areas, transmission occurs primarily perinatally or in early childhood. In areas with intermediate endemicity, infection occurs in all age groups. In areas of low hepatitis B seroprevalence, most infections occur in adults, especially among persons belonging to defined risk groups. Since the development of chronic infection is age-dependent, children can account for a high proportion of chronic hepatitis B infections. The risk of chronic infection is highest when infection is acquired early in life. Chronic infection is responsible for most HBV-related morbidity and mortality.
It has been estimated that between 140,000 to 400,000 new cases of acute hepatitis B occur annually in the Americas. Two thirds of them are believed to occur in South America, primarily in areas within the Amazon Basin.
The recommendations made at the Ninth TAG meeting are reaffirmed. Hepatitis B vaccination programs should be initiated and continued in areas of high prevalence and among groups at high risk, with wider use depending on the epidemiological situation and the availability of resources.
During 1990-1991, ongoing hepatitis B vaccination programs have been continued and amplified in Colombia, Brazil and Venezuela. In addition, vaccination programs have been initiated in several high hepatitis B virus endemic areas in Peru, and prenatal screening of pregnant women with vaccination of children born to hepatitis B virus carrier Mathers has been started in Cuba and Honduras. The needs to increase the availability of hepatitis serologic testing and improbé hepatitis surveillance in order to distinguish various types of acute hepatitis and determine causes of chronic liver disease, were reviewed.
The cost of hepatitis B vaccine remains very high compared to the costs of other vaccines. Considering the known magnitude of hepatitis B problem, its use cannot presently be recommended except in selected areas of the few countries which now experience high endemicity. In such areas, efforts should be made to integrate hepatitis B vaccine into the EPI program. In other areas, vaccination of Elath care workers should be encouraged. To assist in better definition of problem areas, epidemiological, including serological surveys are warranted. Meanwhile, all possible efforts should be made through UNICEF and other procurement agencies to obtain vaccine at a substantially lower cost. The extent of recommended future use will be inversely related to vaccine cost.
HBV infection is a serious public health problem in the Americas. Patterns of HBV infection in this Region vary from low to very high endemicity levels. Low prevalence of HBV surface antigen (HBsAg) carrie state (0.1 to 1.0%) is found in temperate areas of North and South America, in parts of Middle America and the Caribbean, and in Mexico. Moderate levels of HBsAg (1.4 to 28%) are found in parts of tropical Middle and South America. Very high prevalence of HBsAg (5 to15%) occurs in the western parts of the Amazon Basin, in some Caribbean Islands (Hispaniola, and St. Kitts and Nevis), and in some areas of Brazil, Colombia, Peru and Venezuela. There are about 6.3 million chronic HBsAG Carriers int he Americas, of which 5.5. million live in Latin America and the Caribbean.
Fulminant hepatitis associated with delta infection has been documented in the Western Amazon and in certain areas of Colombia (e.g. Santa Maria, Uraba and Catatumbo areas), Venezuela (among the Yucpa-Bari Indians) and PEru (e.g. Abanacay, Quillabamba). Although scarce information is available on the impact due to the chronic consequences of HBV infection in Latin America and the Caribbean, it is likely proporcional to the level of disease endemicity and, in high endemicity areas, comparable to those in Africa and parts of Asia.
Vaccination is the most effective tool in preventing transmission of HBV. Vaccines are composed of the surface antigen of the hepatitis B virus (HBVsAg) and are produced by two different methods (plasma-derived or recombinant DNA). When administered properly, hepatitis B vaccine induces protection in about 95% of recipients. The plasma-derived vaccine is made from the blood of chronically infected individuals which has been treated to destroy any live virus. It has been shown to be safe and effective. Over 40 million doses have been given over a Lumber of years. Recombinant DNA vaccine is also safe and effective. It appears to be equal to the plasma-derived vaccine in every way. Two countries (Cuba and the United States) manufactured this type of vaccine in our Region.
Three doses of vaccine are considered a full course. In areas such as Latin America and the Caribbean where perinatal transmission of HBV is uncommon, the first dose may be given at six weeks (or later) with the first dose of DPT. The second and third doses should be time to coincide with visits required for other childhood immunizations. Several vaccine manufacturers are attempting to develop a quadrivalent DTP-HBV vaccine. It is believed that such a vaccine will be available for use in about 2-3 years. The availability of this vaccine will contribute significantly to the progress of the universal programs of HBV immunization of infants.
In general HBV immunization in Latin America has been directed towards areas of high HBV endemicity, particularly in those where outbreaks of fulminant hepatitis associated with delta infection have been recognized. Currently immunization demonstration programs are underway in several Latin American countries. One of the main objectives of these programs is to integrate HBV vaccine into EPI Schedule and it is expected that in the future these programs will be extended to all infants from these countries. Vaccination o folder children and health workers has also been implemented in certain areas. So far Cuba, Colombia, the United States and Brazil (in the Amazon Region) are the only countries in the Americas that are implementing universal infant immunization. Immunization of children is also being conducted selectively in other countries such as Venezuela, Costa Rica, Dominican Republic, Peru, and Honduras.
A Group of Experts met on 18 March, to discuss the feasibility of establishing immunization programs against hepatitis B virus within the EPI (see EPI/TAG8/90-17). They discussed and reviewed the epidemiology of hepatitis B in the Region of the Americas, the overall impact f the disease, analyzed the costs and benefits of the introduction of the vaccine within the EPI, and discussed vaccination strategies. Several pilot Studies that have taken place in Brazil, Colombia, Costa Rica, Jamaica, Honduras, Mexico, Venezuela, and Trinidad were reviewed and discussed. Future Project and the implications of widening the use of the vaccine were considered and several recommendations were made.
Regional Office for the Americas of the World Health Organization