Hepatitis B is one of the major diseases of mankind and
is a serious global public health problem. It is preventable with safe and
effective vaccines that have been available since 1982.
Of the 2 billion people who have
been infected with the hepatitis B virus (HBV), more than 350 million have
chronic (lifelong) infections. These chronically infected persons
are at high risk of death from cirrhosis of the liver and liver cancer,
diseases that kill about one million persons each year. Although the
vaccine will not cure chronic hepatitis, it is 95% effective in preventing
chronic infections from developing, and is the first vaccine against a
major human cancer. In 1991, the World Health Organization (WHO) called
for all children to receive the hepatitis B vaccine, and 116 countries
have added this vaccine to their routine immunization programmes. However,
the children in the poorest countries, who need the vaccine the most, have
not been receiving it because their governments cannot afford it.
Fortunately, hepatitis B vaccine will soon be available in these countries
with the assistance of the Global Alliance for Vaccines and Immunization (GAVI)
and the Global Fund for Children's Vaccines.
What is Hepatitis?
Hepatitis means inflammation of the liver, and the most
common cause is infection with one of 5 viruses, called hepatitis A,B,C,D,
and E. All of these viruses can cause an acute disease with symptoms
lasting several weeks including yellowing of the skin and eyes (jaundice);
dark urine; extreme fatigue; nausea; vomiting and abdominal pain. It can
take several months to a year to feel fit again. Hepatitis B virus can
cause chronic infection in which the patient never gets rid of the virus
and many years later develops cirrhosis of the liver or liver cancer. HBV
is the most serious type of viral hepatitis and the only type causing
chronic hepatitis for which a vaccine is available.
Who gets Hepatitis B ?
In much of the developing world, (sub-Saharan Africa,
most of Asia, and the Pacific), most people become infected with HBV
during childhood, and 8% to 10% of people in the general population become
chronically infected. In these regions liver cancer caused by HBV figures
among the first three causes death by cancer in men.
High rates of
chronic HBV infection are also found in the Amazon and the southern parts
of Eastern and Central Europe. In the Middle East and Indian
sub-continent, about 5% are chronically infected. Infection is less common
in Western Europe and North America, where less than 1% are chronically
infected.
Young children who become infected with HBV are the
most likely to develop chronic infection. About 90% of infants infected
during the first year of life and 30% to 50% of children infected between
1 to 4 years of age develop chronic infection. The risk of death from
HBV-related liver cancer or cirrhosis is approximately 25% for persons who
become chronically infected during childhood.
How do people get infected ?
Hepatitis B virus is transmitted by contact with blood
or body fluids of an infected person in the same way as human
immunodeficiency virus (HIV), the virus that causes AIDS. However, HBV is
50 to 100 times more infectious than HIV.
The main ways of getting infected with HBV are:
- Perinatal (from mother to baby at the birth);
- Child- to-child transmission;
- Unsafe injections and
transfusions;
Worldwide, most
infections occur from infected mother to child, from child to child
contact in household settings, and from reuse of unsterilized needles and
syringes. In many developing countries, almost all children become
infected with the virus.
In many industrialized countries (e.g. Western Europe
and North America), the pattern of transmission is different. In these
countries, mother-to-infant and child-to-child transmission accounted for
up to one third of chronic infections before childhood hepatitis B
vaccination programmes were implemented. However, the majority of
infections in these countries are acquired during young adulthood by
sexual activity, and injecting drug use. In addition, hepatitis B virus is
the major infectious occupational hazard of health workers, and most
health care workers have received hepatitis B vaccine.
Hepatitis B virus is not spread by contaminated food or
water, and cannot be spread casually in the workplace.
Can chronic hepatitis B and liver cancer be treated?
Liver cancer is almost always fatal, and usually
develops between 35 and 65 years of age, when people are maximally
productive and with family responsibilities. The loss of a mother or a
father in a developing country can devastate the entire family. In
developing countries, most people with liver cancer die within months of
diagnosis. In industrialized countries, surgery and chemotherapy can
prolong life up to a few years. Chronic hepatitis B in some patients is
treated with drugs called interferon or lamivudine, which can help
some patients. However, interferon or lamivudine therapy
costs thousands of dollars and will never be available to most patients in
developing countries. Patients with cirrhosis are sometimes given liver
transplants, with varying success. It is preferable to prevent this
disease with vaccine than to try and cure it.
How safe and effective is the vaccine?
Hepatitis B vaccine has an outstanding record of safety
and effectiveness. Since 1982, over one billion doses of hepatitis B
vaccine have been used worldwide. The vaccine is given as a series of
three intramuscular doses. Studies have shown that the vaccine is 95%
effective in preventing children and adults from developing chronic
infection if they have not yet been infected. In many countries where 8%
to 15% of children used to become chronically infected with HBV, the rate
of chronic infection has been reduced to less than 1% in immunized groups
of children.
How is WHO trying to control Hepatitis B?
Since 1991, WHO has called for all countries to add
hepatitis B vaccine into their national immunization programmes. As of
March 2000, 116 countries had included hepatitis B vaccine in their
national programmes including most countries in Eastern and South- East
Asia, the Pacific Islands, Australia, North and South America, Western
Europe and the Middle East. However, many low income countries in
sub-Saharan Africa, the Indian subcontinent and in the Newly Independent
States do not use the vaccine. The price of the hepatitis B vaccine has
been one of the main obstacles to its introduction in many of these
countries.
The Global Alliance for Vaccines and Immunization (GAVI)
was created in 1999. It is a unique coalition of public and private
institutions where WHO has taken a leading role. The main mission of GAVI
is to vaccinate as many children as possible against vaccine-preventable
diseases. GAVI has introduced a new approach to international health
funding: the Global Fund for Children's vaccines (GFCV). This fund will
help 74 low-income countries to reinforce their national vaccine
programmes and introduce hepatitis B, yellow fever and haemophilus
influenzae type b(Hib) vaccines into their national immunization
programmes.
