Hepatitis B vaccine
Encyclopedia
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.
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 It was withdrawn from the marketplace when Pablo DT Valenzuela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.
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.
(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 intradermal administration or to a high dose vaccine or to a double dose of a combined Hepatitis A and B vaccine. 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.
(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. There have been numerous reports that the Hepatitis B vaccine is linked to Chronic Fatigue Syndrome
, a syndrome marked by severe fatigue, brain fogs, and muscle pains among other symptoms.
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.
The World Health Organization
recommends a pentavalent vaccine, combining vaccines against diphtheria
, tetanus
, pertussis
and Haemophilus influenzae type B
with the vaccine against hepatitis B. There is not yet sufficient evidence on how effective this pentavalent vaccine is in relation to the individual vaccines.
Vaccine
A vaccine is a biological preparation that improves immunity to a particular disease. A vaccine typically contains an agent that resembles a disease-causing microorganism, and is often made from weakened or killed forms of the microbe or its toxins...
developed for the prevention of hepatitis B virus infection. The vaccine contains one of the viral envelope proteins, hepatitis B surface antigen (HBsAg
Hbsag
HBsAg is the surface antigen of the Hepatitis-B-Virus . It indicates current Hepatitis B infection.-Structure and function:The capsid of a virus has different surface proteins from the rest of the virus which act as antigens...
). 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
Antibody
An antibody, also known as an immunoglobulin, is a large Y-shaped protein used by the immune system to identify and neutralize foreign objects such as bacteria and viruses. The antibody recognizes a unique part of the foreign target, termed an antigen...
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
Baker's yeast
Baker's yeast is the common name for the strains of yeast commonly used as a leavening agent in baking bread and bakery products, where it converts the fermentable sugars present in the dough into carbon dioxide and ethanol...
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 HillemanMaurice Hilleman
Maurice Ralph Hilleman was an American microbiologist who specialized in vaccinology and developed over three dozen vaccines, more than any other scientist...
at Merck
Merck & Co.
Merck & Co., Inc. , also known as Merck Sharp & Dohme or MSD outside the United States and Canada, is one of the largest pharmaceutical companies in the world. The Merck headquarters is located in Whitehouse Station, New Jersey, an unincorporated area in Readington Township...
used three treatments (pepsin
Pepsin
Pepsin is an enzyme whose precursor form is released by the chief cells in the stomach and that degrades food proteins into peptides. It was discovered in 1836 by Theodor Schwann who also coined its name from the Greek word pepsis, meaning digestion...
, urea
Urea
Urea or carbamide is an organic compound with the chemical formula CO2. The molecule has two —NH2 groups joined by a carbonyl functional group....
and formaldehyde
Formaldehyde
Formaldehyde is an organic compound with the formula CH2O. It is the simplest aldehyde, hence its systematic name methanal.Formaldehyde is a colorless gas with a characteristic pungent odor. It is an important precursor to many other chemical compounds, especially for polymers...
) 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
Pablo DT Valenzuela
Pablo DT Valenzuela is a Chilean biochemist dedicated to biotechnology development. He is known for his genetic studies of hepatic viruses; participated as R&D Director in the discovery of Hepatitis C virus and the invention of the first recombinant vaccine, against Hepatitis B virus...
, Research Director of Chiron Corporation
Chiron Corporation
Chiron Corporation was a multinational biotechnology firm based in Emeryville, California that was acquired by Novartis International AG on April 20, 2006. It had offices and facilities in eighteen countries on five continents. Chiron's business and research was in three main areas:...
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 ware 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
Liver cancer
Liver tumors or hepatic tumors are tumors or growths on or in the liver . Several distinct types of tumors can develop in the liver because the liver is made up of various cell types. These growths can be benign or malignant...
. This was reported in Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...
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.
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 antigenHepatitis B virus
Hepatitis B is an infectious illness caused by hepatitis B virus which infects the liver of hominoidea, including humans, and causes an inflammation called hepatitis. Originally known as "serum hepatitis", the disease has caused epidemics in parts of Asia and Africa, and it is endemic in China...
(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 intradermal administration or to a high dose vaccine or to a double dose of a combined Hepatitis A and B vaccine. 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
It is now believed that the hepatitis B vaccine provides indefinite protection. However, it was previously believed and suggested that the vaccination would only 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 sclerosisMultiple sclerosis
Multiple sclerosis is an inflammatory disease in which the fatty myelin sheaths around the axons of the brain and spinal cord are damaged, leading to demyelination and scarring as well as a broad spectrum of signs and symptoms...
(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. There have been numerous reports that the Hepatitis B vaccine is linked to Chronic Fatigue Syndrome
Chronic fatigue syndrome
Chronic fatigue syndrome is the most common name used to designate a significantly debilitating medical disorder or group of disorders generally defined by persistent fatigue accompanied by other specific symptoms for a minimum of six months, not due to ongoing exertion, not substantially...
, a syndrome marked by severe fatigue, brain fogs, and muscle pains among other symptoms.
The Engerix B vaccine contained Thiomersal
Thiomersal
Thiomersal , and commonly known in the US as thimerosal, is an organomercury compound. This compound is a well established antiseptic and antifungal agent....
, a mercury containing vaccine preservative that is being phased out at the urging of the Public Health Service in the US.
The World Health Organization
World Health Organization
The World Health Organization is a specialized agency of the United Nations that acts as a coordinating authority on international public health. Established on 7 April 1948, with headquarters in Geneva, Switzerland, the agency inherited the mandate and resources of its predecessor, the Health...
recommends a pentavalent vaccine, combining vaccines against diphtheria
Diphtheria
Diphtheria is an upper respiratory tract illness caused by Corynebacterium diphtheriae, a facultative anaerobic, Gram-positive bacterium. It is characterized by sore throat, low fever, and an adherent membrane on the tonsils, pharynx, and/or nasal cavity...
, tetanus
Tetanus
Tetanus is a medical condition characterized by a prolonged contraction of skeletal muscle fibers. The primary symptoms are caused by tetanospasmin, a neurotoxin produced by the Gram-positive, rod-shaped, obligate anaerobic bacterium Clostridium tetani...
, pertussis
Pertussis
Pertussis, also known as whooping cough , is a highly contagious bacterial disease caused by Bordetella pertussis. Symptoms are initially mild, and then develop into severe coughing fits, which produce the namesake high-pitched "whoop" sound in infected babies and children when they inhale air...
and Haemophilus influenzae type B
Haemophilus influenzae
Haemophilus influenzae, formerly called Pfeiffer's bacillus or Bacillus influenzae, Gram-negative, rod-shaped bacterium first described in 1892 by Richard Pfeiffer during an influenza pandemic. A member of the Pasteurellaceae family, it is generally aerobic, but can grow as a facultative anaerobe. H...
with the vaccine against hepatitis B. There is not yet sufficient evidence on how effective this pentavalent vaccine is in relation to the individual vaccines.