Hemophilus influenzae serotype B (Hib) is a bacterium that can cause a broad range of illnesses. While these health problems mostly affect children under five, they might also harm adults with specific medical conditions. Hib bacteria can cause ailments such as pneumonia, severe swelling in the throat, as well as infections of the blood, ear, joints, bones, and covering of the heart. Severe Hib infection also referred to as “invasive Hib disease,” requires hospital-based care and occasionally might have fatal consequences. One such condition is bacterial meningitis, which is an infection of the lining of the brain and spinal cord. This might lead to deafness and brain damage, especially in children below the age of five years.
The World Health Organisation recommended that all nations incorporate the Hib vaccine into their routine infant immunisation programs. As a result, by June 2011, 170 countries worldwide had adopted the Hib vaccine in their national immunisation programmes. In light of the vaccine’s critical role in shielding kids from potentially fatal Hemophilus influenzae type B infections, this article discusses the mechanism of action, dosage, indications, contraindications, and adverse effects of the Hib influenzae vaccine.
How important is the Hib vaccine?
As was already noted, the main benefit of the Hib vaccine is that it shields children against meningitis, the most prevalent form of the disease that affects the outer layer of the brain and spinal cord and can be fatal. The incidence of Hib illness is further reduced by the reduction in nasopharyngeal colonisation caused by the bacterium following vaccines.
Vaccinations against Hib infections have significant indirect benefits in addition to the effects that are clearly linked to the vaccine. Indirect advantages include reduced antibiotic resistance and herd immunity. These advantages have been adequately established by post-introduction studies where Hib illness has been brought close to near-elimination; these studies have taken place in both industrialised and developing nations, including those with moderate to low rates of immunisation coverage.
Just as vaccines like the Hib vaccine are essential for preventing certain diseases, it’s important to understand the available treatments for conditions like hepatitis D.
What is the vaccination schedule for Hemophilus influenzae type B in India?
The Hib vaccine is available in monovalent form or in combination with other antigens, such as DTP and/or hepatitis B antigens. It is formulated in liquid and lyophilised forms. Hib vaccines have been around for more than 20 years and have proven to be economical and helpful in preventing severe infections.
It is recommended that all infants receive the three doses of the pentavalent Hib vaccine. The first dose is given when the baby is six weeks old or older. At the ages of 10 and 14 weeks, the second and third dosages are given. In India, the UIP does not recommend obtaining a booster dose for children under the age of one who are eligible for the vaccination.
The Hib vaccine catch-up schedule:
For Hib vaccinations, the catch-up strategy is based on the child’s age at the commencement of the vaccination schedule and the number of doses, if any, that they have already received.
For young, healthy children who are at least five years old, have not had any previous Hib vaccines, or have an incomplete Hib schedule, there is no need for them to have any further Hib immunisations.
Additionally, it is advised that children aged 1 to 5 who are receiving radiation therapy or chemotherapy, have anatomic or functional asplenia, have tested positive for HIV, or are immunoglobulin/complement deficient should receive the Hib vaccine once more. The recommendation for such patients is as follows:
- The ones who have had only one dose by the time they became one year old should receive two additional doses of the Hib vaccination, spaced eight weeks apart.
- Those who have received at least two doses of the Hib vaccination by the time they became one year old, should receive one more dose at least eight weeks following the last one.
- If a dose is administered within 14 days of the start of chemotherapy or radiation therapy, one more vaccine shot should be administered within three months after chemotherapy is completed.
- One dosage should be administered at least two weeks prior to the procedure for individuals undergoing an elective splenectomy who are at least 15 months old and have never received a Hib immunisation.
- An individual with HIV who is between the ages of 5 and 18 years and who has never gotten the Hib vaccine should receive one dose.
- Within six to twelve months following a successful transplant, all recipients of haematopoietic stem cell transplants should receive three doses of the Hib vaccine, spaced four weeks apart.
How does the vaccine against Hib infection work?
Polyribosyl ribitol phosphate (PRP), the component of the Hib polysaccharide capsule, functions as an antigen without drawing in T lymphocytes, just like other polysaccharide capsules. Consequently, because the T-cell independent immunological mechanism only produces a tiny amount of antibodies, the polysaccharide version of the vaccine is not immune-stimulating before the age of two.
The conjugate version of the vaccine, on the other hand, which draws T cells and generates an adequate amount of anti-PRP antibodies, is made possible by the covalent attachment of the PRP capsule to a protein. As of 2019, the Hib vaccinations use either the tetanus toxoid conjugate or the meningococcal protein conjugate.
According to research, using the Hib vaccine in combination with the acellular pertussis vaccine—as is the case with the acellular pertussis vaccine adsorbed, inactivated poliovirus, and Hemophilus b conjugate (tetanus toxoid conjugate) vaccine—this (DTaP-IPV/Hib) combination reduces immunogenicity and may be a factor in the Hib vaccine’s failures.
Significantly, there is no evidence that administering the Hib vaccination plus DTap—which contains acellular pertussis—at separate injection sites on the same day will result in a lower level of immunogenicity or more Hib vaccine failures.
Who should not receive the Hib vaccine?
There are only two existing conditions that preclude a person from getting subsequent doses of the Hib vaccination:
- Ages under six weeks old are an absolute contraindication to the Hib vaccination.
- Additionally, the history of severe hypersensitivity reactions, such as anaphylaxis, to the vaccine or any of its ingredients is also not an indication of the Hib vaccine.
Individuals with a history of severe allergies to natural rubber latex should not get the Hemophilus b conjugate vaccines containing tetanus toxoid and meningococcal protein.
With the inclusion of inactivated poliovirus, acellular pertussis adsorbed, and Hemophilus b conjugate (tetanus toxoid conjugate), the combination vaccination has several relative contraindications of its own that should be taken into account.
Which adverse effects are associated with the Hemophilus influenzae vaccine?
The adverse events (AEs) or reactions from the Hib vaccination fall into two categories: serious and non-serious. Serious adverse events are those that cause a lasting disability, prolong hospital stays, result in death, or pose a serious threat to life. The serious AEs associated with the Hib vaccine include high-grade fever, vomiting, convulsions, irritability, intussusception, diarrhoea, hypotonia, lethargy, and apnoea.
A few of the less serious adverse reactions (AEs) include a low-grade temperature, injection-site swelling or erythema, crying, rash, anxiety, screaming, and hives.
The successful implementation of Hib vaccine in India:
The introduction of the Hemophilus influenzae type B (Hib) vaccine has revolutionised public health in India by substantially reducing the incidence of diseases caused by this bacterium, including meningitis and pneumonia. In 2011, India became the first country to offer the Hib vaccine as part of the Universal Immunisation Program (UIP). The vaccine was designed to protect young children and newborns, who are particularly susceptible to serious diseases brought on by Hemophilus influenzae type b. Since then, the Ministry of Health and Family Welfare of the Government of India has made sure that the vaccination is widely accessible throughout the nation.
The introduction of Hib vaccine by the Indian government as a pentavalent vaccine (LPV) in combination with DPT and HepB in a 10-dose presentation should be emphasised. There are some definite programmatic benefits to using combination formulation. Initially, there will be fewer injections per finished schedule, which means fewer syringes will be needed and less potentially hazardous sharps waste will be produced. Additionally, as a single vial of LPV replaces DPT and Hep B vials, cold chain space will be saved.
The government’s persistent initiatives, such as regular vaccination drives and information campaigns, have greatly raised vaccine coverage and helped to lower the prevalence of illnesses linked to Hib. The National Family Health Survey and other official data demonstrate the effectiveness of these efforts by displaying higher immunisation rates across a number of states. The Government of India continues to prioritise the Hib vaccination as part of a larger plan to improve child health and lower the death rate among children under five. It makes sure the vaccine is included in regular vaccination regimens and works towards achieving universal coverage across all areas.
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