Hib vaccine
Encyclopedia
Haemophilus influenzae type B vaccine (Hib janan or PRP vaccine) is a conjugate vaccine
developed for the prevention of invasive disease caused by Haemophilus influenzae type b bacteria. The Centers for Disease Control and Prevention
(CDC) has recommended the use of the Hib vaccine. Due to routine use of the Hib vaccine in the U.S.
from 1980 to 1990
, the incidence of invasive Hib disease has decreased from 40-100 per 100,000 child
ren down to 1.3 per 100,000. Vaccinations against Haemophilus influenzae
(Hib) have decreased early childhood meningitis
significantly in developed countries
and recently in developing countries
.
vaccine, first marketed in the US in 1985. Similar to other polysaccharide vaccines, immune response to the vaccine was highly age-dependent. Children under 18 months of age did not produce a positive response for this vaccine. As a result, the age group with the highest incidence of Hib disease was unprotected, limiting the usefulness of the vaccine. The vaccine was withdrawn from the market in 1988.
conjugate vaccine. Attaching Hib polysaccharide to a protein carrier greatly increased the ability of the immune system of young children to recognize the polysaccharide and develop immunity
. There are currently three types of conjugate vaccine utilizing different proteins in the conjugation process, all of which are highly effective: tetanospasmin
(also called tetanus toxin), mutant
diphtheria
protein, and meningococcal
group B outer membrane
protein.
-polio vaccine
s and Hepatitis B vaccine
s are available in the US. The World Health Organization
(WHO) has certified several Hib vaccine combinations, including a pentavalent diphtheria-pertussis-tetanus-hepatitis B-Hib, for use in developing countries. There is not yet sufficient evidence on how effective this combined pentavalent vaccine is in relation to the individual vaccines.
among fully vaccinated children estimated to be between 95-100%. The vaccine has also been shown to be immunogenic in patients at high risk of invasive disease. Hib vaccine is not effective against non-type B Haemophilus influenzae. However, non-type B disease is rare in comparison to pre-vaccine Haemophilus influenzae type B disease. (Source?)
s and ongoing surveillance have shown Hib vaccine to be safe. In general, adverse reactions to the vaccine are mild. The most common reactions are transient redness, swelling
, or pain
at the site of injection, occurring in 5-30% of vaccine recipients. More severe reactions are extremely rare.(source?)
, and inflammation
of the epiglottis
in the United States, causing an estimated 20,000 cases a year in the early 1980s, mostly in children under 5 years old. Since routine vaccination began, the incidence of Hib disease has declined by greater than 99%, effectively eliminating Hib as a public health
problem. Similar reductions in disease occurred after introduction of the vaccine in Western Europe
and developing countries.
; children infected with Hib carry the bacteria in their nasal passages while clearing the infection. These Hib-carrying children would regularly infect adults. The practice of vaccinating children eliminated the source of the bacteria, reducing the rate of Hib in adults.
s be vaccinated using a polysaccharide-protein conjugate Hib vaccine, starting after the age of 6 weeks. Specific immunization schedule depends on choice of vaccine and local recommendations.
s in many countries were struggling with the current vaccines they were trying to deliver.
of Hib vaccine for countries interested in using the vaccine, as well as financial support for vaccine systems and safe injections. In addition, GAVI created the Hib Initiative to catalyze uptake of the vaccine. The Hib Initiative uses a combination of collecting and disseminating existing data, research, and advocacy to assist countries in the making a decision about using the Hib vaccine. , 61 out of 72 low-income countries are planning on introducing the vaccine by the end of 2009.
Conjugate vaccine
A conjugate vaccine is created by covalently attaching a poor antigen to a carrier protein , thereby conferring the immunological attributes of the carrier on the attached antigen...
developed for the prevention of invasive disease caused by Haemophilus influenzae type b bacteria. The Centers for Disease Control and Prevention
Centers for Disease Control and Prevention
The Centers for Disease Control and Prevention are a United States federal agency under the Department of Health and Human Services headquartered in Druid Hills, unincorporated DeKalb County, Georgia, in Greater Atlanta...
(CDC) has recommended the use of the Hib vaccine. Due to routine use of the Hib vaccine in the U.S.
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
from 1980 to 1990
1980s
File:1980s decade montage.png|thumb|400px|From left, clockwise: The first Space Shuttle, Columbia, lifted off in 1981; American President Ronald Reagan and Soviet leader Mikhail Gorbachev eased tensions between the two superpowers, leading to the end of the Cold War; The Fall of the Berlin Wall in...
, the incidence of invasive Hib disease has decreased from 40-100 per 100,000 child
Child
Biologically, a child is generally a human between the stages of birth and puberty. Some vernacular definitions of a child include the fetus, as being an unborn child. The legal definition of "child" generally refers to a minor, otherwise known as a person younger than the age of majority...
ren down to 1.3 per 100,000. Vaccinations against Haemophilus influenzae
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...
(Hib) have decreased early childhood meningitis
Meningitis
Meningitis is inflammation of the protective membranes covering the brain and spinal cord, known collectively as the meninges. The inflammation may be caused by infection with viruses, bacteria, or other microorganisms, and less commonly by certain drugs...
significantly in developed countries
Developed country
A developed country is a country that has a high level of development according to some criteria. Which criteria, and which countries are classified as being developed, is a contentious issue...
and recently in developing countries
Developing country
A developing country, also known as a less-developed country, is a nation with a low level of material well-being. Since no single definition of the term developing country is recognized internationally, the levels of development may vary widely within so-called developing countries...
.
Polysaccharide vaccine
The first Hib vaccine licensed was a pure polysaccharidePolysaccharide
Polysaccharides are long carbohydrate molecules, of repeated monomer units joined together by glycosidic bonds. They range in structure from linear to highly branched. Polysaccharides are often quite heterogeneous, containing slight modifications of the repeating unit. Depending on the structure,...
vaccine, first marketed in the US in 1985. Similar to other polysaccharide vaccines, immune response to the vaccine was highly age-dependent. Children under 18 months of age did not produce a positive response for this vaccine. As a result, the age group with the highest incidence of Hib disease was unprotected, limiting the usefulness of the vaccine. The vaccine was withdrawn from the market in 1988.
Conjugate vaccine
The shortcomings of the polysaccharide vaccine lead to the production of the Hib polysaccharide-proteinProtein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
conjugate vaccine. Attaching Hib polysaccharide to a protein carrier greatly increased the ability of the immune system of young children to recognize the polysaccharide and develop immunity
Immunity (medical)
Immunity is a biological term that describes a state of having sufficient biological defenses to avoid infection, disease, or other unwanted biological invasion. Immunity involves both specific and non-specific components. The non-specific components act either as barriers or as eliminators of wide...
. There are currently three types of conjugate vaccine utilizing different proteins in the conjugation process, all of which are highly effective: tetanospasmin
Tetanospasmin
Tetanus toxin is an extremely potent neurotoxin produced by the vegetative cell of Clostridium tetani in anaerobic conditions, causing tetanus. It has no known function for clostridia in the soil environment where they are normally encountered. It is also called spasmogenic toxin, tetanospasmin or...
(also called tetanus toxin), mutant
Mutant
In biology and especially genetics, a mutant is an individual, organism, or new genetic character, arising or resulting from an instance of mutation, which is a base-pair sequence change within the DNA of a gene or chromosome of an organism resulting in the creation of a new character or trait not...
diphtheria
Corynebacterium diphtheriae
Corynebacterium diphtheriae is a pathogenic bacterium that causes diphtheria. It is also known as the Klebs-Löffler bacillus, because it was discovered in 1884 by German bacteriologists Edwin Klebs and Friedrich Löffler .-Classification:Four subspecies are recognized: C. diphtheriae mitis, C....
protein, and meningococcal
Neisseria meningitidis
Neisseria meningitidis, often referred to as meningococcus, is a bacterium that can cause meningitis and other forms of meningococcal disease such as meningococcemia, a life threatening sepsis. N. meningitidis is a major cause of morbidity and mortality during childhood in industrialized countries...
group B outer membrane
Cell membrane
The cell membrane or plasma membrane is a biological membrane that separates the interior of all cells from the outside environment. The cell membrane is selectively permeable to ions and organic molecules and controls the movement of substances in and out of cells. It basically protects the cell...
protein.
Combination vaccines
Multiple combinations of Hib and other vaccines have been licensed in the United States, reducing the number of shots necessary to vaccinate a child. Hib vaccine combined with diphtheria-tetanus-pertussisDPT vaccine
DPT refers to a class of combination vaccines against three infectious diseases in humans: diphtheria, pertussis and tetanus...
-polio vaccine
Polio vaccine
Two polio vaccines are used throughout the world to combat poliomyelitis . The first was developed by Jonas Salk and first tested in 1952. Announced to the world by Salk on April 12, 1955, it consists of an injected dose of inactivated poliovirus. An oral vaccine was developed by Albert Sabin...
s and Hepatitis B vaccine
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 . It is produced by yeast cells, into which the genetic code for HBsAg has been inserted...
s are available 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...
(WHO) has certified several Hib vaccine combinations, including a pentavalent diphtheria-pertussis-tetanus-hepatitis B-Hib, for use in developing countries. There is not yet sufficient evidence on how effective this combined pentavalent vaccine is in relation to the individual vaccines.
Efficacy
Hib conjugate vaccines have been shown to be universally effective against all manifestations of Hib disease, with a clinical efficacyEfficacy
Efficacy is the capacity to produce an effect. It has different specific meanings in different fields. In medicine, it is the ability of an intervention or drug to reproduce a desired effect in expert hands and under ideal circumstances.- Healthcare :...
among fully vaccinated children estimated to be between 95-100%. The vaccine has also been shown to be immunogenic in patients at high risk of invasive disease. Hib vaccine is not effective against non-type B Haemophilus influenzae. However, non-type B disease is rare in comparison to pre-vaccine Haemophilus influenzae type B disease. (Source?)
Safety
Clinical trialClinical trial
Clinical trials are a set of procedures in medical research and drug development that are conducted to allow safety and efficacy data to be collected for health interventions...
s and ongoing surveillance have shown Hib vaccine to be safe. In general, adverse reactions to the vaccine are mild. The most common reactions are transient redness, swelling
Swelling (medical)
In medical parlance, swelling is the transient enlargement or protuberance in the body and may include tumors. According to cause, it may be congenital, traumatic, inflammatory, neoplastic or miscellaneous....
, or pain
Pain
Pain is an unpleasant sensation often caused by intense or damaging stimuli such as stubbing a toe, burning a finger, putting iodine on a cut, and bumping the "funny bone."...
at the site of injection, occurring in 5-30% of vaccine recipients. More severe reactions are extremely rare.(source?)
Impact
Prior to introduction of the conjugate vaccine, Hib was a leading cause of childhood meningitis, pneumoniaPneumonia
Pneumonia is an inflammatory condition of the lung—especially affecting the microscopic air sacs —associated with fever, chest symptoms, and a lack of air space on a chest X-ray. Pneumonia is typically caused by an infection but there are a number of other causes...
, and inflammation
Inflammation
Inflammation is part of the complex biological response of vascular tissues to harmful stimuli, such as pathogens, damaged cells, or irritants. Inflammation is a protective attempt by the organism to remove the injurious stimuli and to initiate the healing process...
of the epiglottis
Epiglottis
The epiglottis is a flap that is made of elastic cartilage tissue covered with a mucous membrane, attached to the entrance of the larynx. It projects obliquely upwards behind the tongue and the hyoid bone, pointing dorsally. The term, like tonsils, is often incorrectly used to refer to the uvula...
in the United States, causing an estimated 20,000 cases a year in the early 1980s, mostly in children under 5 years old. Since routine vaccination began, the incidence of Hib disease has declined by greater than 99%, effectively eliminating Hib as a public health
Public health
Public health is "the science and art of preventing disease, prolonging life and promoting health through the organized efforts and informed choices of society, organizations, public and private, communities and individuals" . It is concerned with threats to health based on population health...
problem. Similar reductions in disease occurred after introduction of the vaccine in Western Europe
Western Europe
Western Europe is a loose term for the collection of countries in the western most region of the European continents, though this definition is context-dependent and carries cultural and political connotations. One definition describes Western Europe as a geographic entity—the region lying in the...
and developing countries.
Herd immunity
Although Hib vaccine is given to children, Hib infections have also decreased in adults. This decrease occurred because of herd immunityHerd immunity
Herd immunity describes a form of immunity that occurs when the vaccination of a significant portion of a population provides a measure of protection for individuals who have not developed immunity...
; children infected with Hib carry the bacteria in their nasal passages while clearing the infection. These Hib-carrying children would regularly infect adults. The practice of vaccinating children eliminated the source of the bacteria, reducing the rate of Hib in adults.
Recommendations
The CDC and WHO currently recommend that all infantInfant
A newborn or baby is the very young offspring of a human or other mammal. A newborn is an infant who is within hours, days, or up to a few weeks from birth. In medical contexts, newborn or neonate refers to an infant in the first 28 days after birth...
s be vaccinated using a polysaccharide-protein conjugate Hib vaccine, starting after the age of 6 weeks. Specific immunization schedule depends on choice of vaccine and local recommendations.
Vaccination in the developing world
Introduction of Hib vaccine in developing countries lagged behind that in developed countries for several reasons. The expense of the vaccine was large in comparison to the standard EPI vaccines. Poor disease surveillance systems and inadequate hospital laboratories failed to detect the disease, leading many experts to believe that Hib did not exist in their countries. And health systemHealth system
A health system can be defined as the structured and interrelated set of all actors and institutions contributing to health improvement. The health system boundaries could then be referred to the concept of health action, which is "any set of activities whose primary intent is to improve or...
s in many countries were struggling with the current vaccines they were trying to deliver.
GAVI and the Hib Initiative
In order to remedy these issues, the GAVI Alliance took active interest in the vaccine. GAVI offers substantial subsidizationSubsidy
A subsidy is an assistance paid to a business or economic sector. Most subsidies are made by the government to producers or distributors in an industry to prevent the decline of that industry or an increase in the prices of its products or simply to encourage it to hire more labor A subsidy (also...
of Hib vaccine for countries interested in using the vaccine, as well as financial support for vaccine systems and safe injections. In addition, GAVI created the Hib Initiative to catalyze uptake of the vaccine. The Hib Initiative uses a combination of collecting and disseminating existing data, research, and advocacy to assist countries in the making a decision about using the Hib vaccine. , 61 out of 72 low-income countries are planning on introducing the vaccine by the end of 2009.