Hepatitis B
Babies and young children are most at risk from Hepatitis B, a viral disease, which infects the liver and is transmitted via blood or other body fluids. GAVI funds have been helping developing countries immunise newborn babies with hepatitis B vaccine since 2000.
What is Hepatitis B?
Hepatitis B can lead to acute hepatitis B, chronic hepatitis B virus (HBV) infection, liver cirrhosis, and hepatocellular cancer.
Infections in the developing world are mostly from mother to child, or from child to child, mainly through cuts, bites, scrapes, and scratches. Unsafe injections, blood transfusions, and sexual contact also account for some HBV transmission.
In the developed world, drug injections and sexual activity are the major cause of infections.
No specific treatment exists for acute hepatitis B. Symptomatic care is given, such as fluid replacement to counteract losses from vomiting and diarrhoea.
HBV infection can cause jaundice, dark urine, fatigue, nausea, vomiting and abdominal pain.
Chronic HBV infection is treatable with drugs, such as anti-viral and interferon agents. Interferon is the most effective but is only successful in 40-50 percent of cases. In general, annual treatment costs thousands of dollars and is unattainable in the developing world.
Cirrhosis treatment may involve liver transplants, and liver cancer patients may receive surgery or chemotherapy; none of these are generally unavailable in the developing world.
Who is at risk?
More than two billion people are infected by HBV worldwide of whom 360 million suffer from chronic HBV infection.
Children, especially those in the first few months of their lives, are most at risk as 90 percent of infants infected in the first year of life will develop chronic HBV infection, as will 30-50 percent of children infected between one and four years of age.
Among adults chronically infected as children, 25 percent will die from HBV-related liver cancer or cirrhosis. But if adults are infected by HBV after childhood, 90 percent will make a full recovery.
Where?
Chronic HBV infection is highly prevalent in sub-Saharan Africa, Southeast Asia, the Eastern Mediterranean region, south and western Pacific islands, the Amazon basin, and the Caribbean.
The vaccine
Two classes of hepatitis B vaccines have been available since 1982: plasma-derived and recombinant vaccines. They are interchangeable, as they are equally effective, sharing the same duration of protection, and thermostability and both inducing protective antibody levels in over 95 percent of infants, children, and young adults.
Currently these vaccines are either used on their own (monovalent vaccines) or in combination with other antigens such as with DTP3 (tetravalent) and DTP3 and Hib (pentavalent).
WHO recommends that routine infant vaccination against HBV forms part of all national immunisation schedules. Countries have been encouraged to introduce immunisation by declining vaccine costs, high cost effectiveness and flexible dosing schedules.
In countries with high mother-to-child transmission rates, the first dose of HBV vaccine is ideally given within 24 hours of birth.
Two possible dosing schedules are considered appropriate to prevent mother-to-child HBV infections:
- Three-dose schedule
- Monovalent first dose, given at birth
- Monovalent or combined vaccine second and third doses, given concurrently with the first and third doses of DTP vaccine.
- Four-dose schedule
- Monovalent first dose, given at birth
- Three monovalent or combined vaccine doses given concurrently with other Expanded Programme on Immunisation (EPI) vaccines.
Catch-up campaign strategies may be considered for countries where there is a low rate of HBV infection. Targeting adolescents and high-risk adults, such as prisoners or health care workers, can supplement routine infant vaccination.
In regions, where there is a high rate of infection, catch-up vaccination is not recommended, as most adults will have already been infected.
GAVI's response
GAVI has been providing support for developing countries introducing hepatitis B vaccine since 2000. To date the Alliance has approved support for the vaccines' purchase (and safe injection equipment) for five years in 67 countries, with DTP3 coverage of 50 to 80 percent. These countries also receive a one-off payment of US$100,000 to facilitate the introduction of the new vaccine. GAVI helps countries develop a financial analysis, part of multi-year plans, to ensure continued funding for hepatitis B vaccine once GAVI support ends.GAVI's backing of pentavalent vaccine, funded by money raised from the sale of IFFIm bonds, has accelerated countries’ uptake of hepatitis B vaccine, because countries are confident there will be a sustainable supply from vaccine manufacturers. Pentavalent is also easier for health workers to administer. By the end of 2008 pentavalent vaccine was being used or had been approved for introduction in 57 countries.
GAVI also works with vaccine manufacturers to ensure that adequate and affordable supplies of hepatitis B vaccine are available in low-income countries.
Since 2000, WHO estimates that a cumulative 192.2 million children have been immunised against hepatitis B.
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