HEPATITIS-B VIRUS

Hepatitis B

Hepatitis B is a disease caused by the hepatitis B virus. The disease mainly affects the liver. However, if you are infected the virus is present in body fluids such blood, saliva, semen and vaginal fluid. In the UK it is estimated that about 1 in 1000 people are infected with the hepatitis B virus. It is much more common in other countries - these include sub-Saharan Africa, most of Asia and the Pacific islands.

If you are infected with the hepatitis B virus, the initial symptoms can range from no symptoms at all to a severe illness. After this 'acute phase', in a number of cases the virus remains in the body long-term. These people are called 'carriers'. Some carriers do not have any symptoms but can still pass on the virus to other people. About 1 in 4 carriers eventually develop a serious liver disease such as chronic hepatitis, cirrhosis, and in some cases liver cancer develops after a number of years. See separate leaflet called 'Hepatitis B' for more details of the disease.

All pregnant women in the UK are offered testing for hepatitis B during each pregnancy.

How is hepatitis B passed on?:

The hepatitis B virus is passed from person to person as a result of:

• Blood to blood contact. For example: drug users sharing needles or other equipment which may be contaminated with infected blood. (Blood used for transfusion is now screened for hepatitis B virus.)
• Having unprotected sex with an infected person.
• From an infected mother passing it to her baby.
• A human bite from an infected person.

Who needs hepatitis B immunisation?:

Anyone who is at increased risk of being infected with the hepatitis B virus should consider being immunised. These include:

• Workers who are likely to come into contact with blood products, or are at increased risk of needlestick injuries, assault, etc. For example: nurses, doctors, dentists, medical laboratory workers, prison wardens, etc. Also, staff at day care or residential centres for people with learning disabilities where there is a risk of scratching or biting by residents.
• People who inject street drugs, their sexual partners and children.
• People who change sexual partners frequently (in particular homosexual men and sex workers).
• People who live in close contact with someone infected with hepatitis B. (You cannot catch hepatitis B from touching people or normal social contact. However, close regular contacts are best immunised.)
• People who regularly receive blood transfusions (for example people with haemophilia).
• People with certain kidney or liver diseases.
• People who live in residential accommodation for those with learning difficulties. People who attend day centres for people with learning difficulties may also be offered immunisation.
• Families adopting children from countries with a high or intermediate prevalence of hepatitis B when the hepatitis B status of the child is unknown. (It is, however, advisable for the child to be tested for hepatitis B.)
• Foster carers or if you live with foster children.
• Prison inmates. Immunisation against hepatitis B is now recommended for all prisoners in the UK.
• Travellers to countries where hepatitis B is common who place themselves at risk when abroad. The risk behaviour includes sexual activity, injecting drug use, undertaking relief work and/or participating in contact sports. Also, if you may need a medical or dental procedure in these countries and the procedure may not be done with sterile equipment.

The immunisation schedule

You need three doses of the vaccine for full protection. The second dose is usually given one month after the first dose. The third dose is given five months after the second dose.

One month after the third dose you may need to have a blood test. You may need one if you are at risk of infection at work, especially as a healthcare or laboratory worker or have certain kidney diseases. Your doctor will be able to advise you if you need a blood test. This checks if you have made antibodies against the hepatitis B virus and are immune. This is because for about 1 in 10 people, three doses of the vaccine are not sufficient and a booster is needed after five years.

The schedule is the same for the combined hepatitis A and B vaccine which is also available.

Rapid immunisation schedule:

A schedule of giving three doses quicker than usual may be used in some situations. That is, three doses with each dose a month apart. An even quicker schedule is also sometimes used. That is, the second dose given seven days after the first and the third dose given 21 days after the first. These quicker schedules may be used if you are at very high risk of infection and need to be immune as soon as possible. For example, if you are soon to travel abroad, are new to prison or are sharing needles to inject drugs. However, a more rapid schedule may not be as effective for long-term immunity unless a fourth dose is given 12 months after the first dose. Your doctor will advise on the best schedule for your circumstances.

Are there any side-effects from hepatitis B immunisation?

Side-effects are uncommon. Occasionally, some people develop soreness and redness at the injection site. Rarely, some people develop a mild fever and a flu-like illness for a few days after the injection.

What if I come into contact with hepatitis B and am not immunised?

Seek medical attention as soon as possible if you have been at risk from a possible source of infection and you are not immunised. For example, if you have a needlestick injury or have been bitten by someone who may have hepatitis B, etc.

You should have an injection of immunoglobulin as soon as possible. This contains antibodies against the virus and gives short term protection. You should also start a course of immunisation. The hepatitis B vaccine is very effective at preventing infection if given shortly after contact with hepatitis B. Even if you have had the hepatitis B vaccine and are at risk of infection (for example by having unprotected sex or sharing contaminated needles) you should ask your doctor for advice as you may be advised to have a booster vaccine or even an injection of immunoglobulin.

Babies who are born to infected mothers should have an injection of immunoglobulin as soon as possible after they are born. They should also be immunised. The first dose of vaccine is given within the first two days after birth. This is followed by three further doses at 1 month, 2 months and 12 months of age.

Who should not receive hepatitis B vaccine?

• If you have an illness causing a high temperature it is best to postpone immunisation until after the illness.
• You should not have a booster if you have had a severe reaction to this vaccine in the past.

The vaccine may be given if you are pregnant or breast feeding and immunisation against hepatitis B is necessary.

 What kind of a virus is hepatitis B?

The hepatitis B virus is a DNA virus, meaning that its genetic material is made up of deoxyribonucleic acids. It belongs to a family of viruses known as Hepadnaviridae. The virus is primarily found in the liver but is also present in the blood and certain body fluids.

Hepatitis B virus consists of a core particle (central portion) and a surrounding envelope (outer coat). The core is made up of DNA and the core antigen (HBcAg). The envelope contains the surface antigen (HBsAg). These antigens are present in the blood and are markers that are used in the diagnosis and evaluation of patients with suspected viral hepatitis.

How does hepatitis B virus cause liver injury?

The hepatitis B virus reproduces in liver cells, but the virus itself is not the direct cause of damage to the liver. Rather, the presence of the virus triggers an immune response from the body as the body tries to eliminate the virus and recover from the infection. This immune response causes inflammation and may seriously injure liver calls. Therefore, there is a balance between the protective and destructive effects of the immune response to the hepatitis B virus.

Hepatitis B vaccine
Hepatitis B vaccine is a vaccine developed for the prevention of hepatitis B virus infection. The vaccine contains one of the viral envelope proteins, hepatitis B surface antigen (HBsAg). It is produced by yeast cells, into which the genetic code for HBsAg has been inserted. A course of three (3) vaccine injections are given with the second injection at least one month after the first dose and the third injection given six months after the first dose. Afterward an immune system antibody to HBsAg is established in the bloodstream. The antibody is known as anti-HBsAg. This antibody and immune system memory then provide immunity to hepatitis B infection.The first vaccine became available in 1981.
A range of vaccines are available in the market. Presently recombinant DNA vaccines are available, which means they are produced by inserting the gene for HBV into common baker's yeast where it is grown, harvested, and purified. HBV infection cannot occur from receiving hepatitis B vaccine.The common brands available are Engerix-B (GSK), Elovac B (Human Biologicals Institute, A division of Indian Immunologicals Limited), Genevac B (Serum Institute), Shanvac B etc.These vaccines are given intramuscularly.
The invention:
The invention of the vaccine began with the realization (by virologist Alfred Prince, in 1968) that the Australia antigen was part of a virus that caused hepatitis. Maurice Hilleman at Merck used three treatments (pepsin, urea and formaldehyde) of blood serum together with rigorous filtration to yield a product that could be used as a safe vaccine. This was first licensed by the FDA in 1981. It was not very successful in the marketplace because clinicians knew that it was a product made from human blood serum. It was withdrawn from the marketplace when Pablo DT Valenzuela, Research Director of Chiron Corporation succeeded in 1986 in making the antigen in yeast and invented the first recombinant vaccine . This is the vaccine still in use today.

Recommended populations:

Babies born to mothers with active hepatitis B infections are recommended to receive treatment reducing the risk of mother-to-child transmission of the hepatitis B infection. As soon as possible and within 48 hours of birth, newborns are vaccinated with hepatitis B surface antigen (HBsAg) and injected with hepatitis B immunoglobulin (HBIG).
Many countries now routinely vaccinate infants against hepatitis B. In countries with high rates of hepatitis B infection, vaccination of newborns has not only reduced the risk of infection, but has also led to marked reduction in liver cancer. This was reported in Taiwan where the implementation of a nationwide hepatitis B vaccination program in 1984 was associated with a decline in the incidence of childhood hepatocellular carcinoma.
In many areas, vaccination against hepatitis B is also required for all health-care and laboratory staff.
 An Australian couple in August 2008 went on the run after the New South Wales Supreme Court extended an order forcing them to immunise their newborn against the disease. DOCS (Department of Community Services) took out the order, as doctors say the five-day-old baby is at a high risk of contracting the illness as his mother has the disease. The parents believe (see Vaccine controversy) that aluminium in the vaccine would cause the baby more harm than the disease itself.

Response to vaccination:

Following the primary course of 3 vaccinations, a blood test may be taken after an interval of 1–4 months to establish if there has been an adequate response, which is defined as an anti-hepatitis B surface antigen (anti-Hbs) antibody level above 100 mIU/ml. Such a full response occurs in about 85-90% of individuals.
An antibody level between 10 and 100 mIU/ml is considered a poor response, and these people should receive a single booster vaccination at this time, but do not need further retesting.
People who fail to respond (anti-Hbs antibody level below 10 mIU/ml) should be tested to exclude current or past Hepatitis B infection, and given a repeat course of 3 vaccinations, followed by further retesting 1–4 months after the second course. Those who still do not respond to a second course of vaccination may respond to a high dose of vaccine or to intradermal administration.Those who still fail to respond will require hepatitis B immunoglobulin (HBIG) if later exposed to the hepatitis B virus.
Poor responses are mostly associated with being over the age of 40 years, obesity and smoking, and also in alcoholics, especially if with advanced liver disease. Patients who are immunosuppressed or on renal dialysis may respond less well and require larger or more frequent doses of vaccine. At least one study suggests that hepatitis B vaccination is less effective in patients with HIV.
Duration of protection:
Although initially it was thought that the hepatitis B vaccine did not provide indefinite protection, this is no longer considered the case. Previous reports had suggested vaccination would provide effective cover of between five and seven years,but subsequently it has been appreciated that long-term immunity derives from immunological memory which outlasts the loss of antibody levels and hence subsequent testing and administration of booster doses is not required in successfully vaccinated immunocompetent individuals.Hence with the passage of time and longer experience, protection has been shown for at least 25 years in those who showed an adequate initial response to the primary course of vaccinations, and UK guidelines now suggest that for initial responders who require ongoing protection, such as for healthcare workers, only a single booster is advocated at 5 years^,

 Safety:

Several studies looked for a significant association between recombinant hepatitis B vaccine (HBV) and multiple sclerosis (MS) in adults. Most published scientific studies do not support a causal relationship between hepatitis B vaccination and demyelinating diseases such as MS. A 2004 study reported a significant increase in risk within 3 years of vaccination. Some of these studies were criticized for methodological problems. This controversy created public misgivings about HB vaccination, and hepatitis B vaccination in children remained low in several countries. A 2007 study found that the vaccination does not seem to increase the risk of a first episode of MS in childhood.
A 2009 study of the hepatitis B vaccine and associated risk of CNS inflammatory demyelination was conducted. The hepatitis B vaccine was found to be generally safe, however the Engerix B vaccine appeared to triple the risk of CNS inflammatory demyelination in infant boys. The Engerix B vaccine contained Thiomersal, a mercury containing vaccine preservative that is being phased out at the urging of the Public Health Service in the US.