hib :: Article CreatorHib Vaccine - Types, Dosage Schedule, Contraindications And Side Effects
What is Hib Vaccine?
The Hib vaccine protects against severe bacterial infections like meningitis, pneumonia, and epiglottitis caused by the bacterium H. Influenzae type b. The Hib bacteria spread through sneezing, coughing, and nasal secretions from an infected person to another person.
The Hib disease is caused by a gram-negative bacterium named Haemophilus influenzae that commonly infects the upper respiratory tracts of children. The germs spread among children through the transfer of nasal secretions during sneezing and coughing. Although children under 5 years are most susceptible to Hib infections, immune-compromised adults can also get infected.
The Hib disease can become invasive when the germs enter the lungs or the bloodstream. Only a minority of those exposed or who are carriers of the organism suffer from the invasive disease. The H influenzae strains that have a polysaccharide (sugar) capsule or coat cause a more serious disease. The H influenzae, type b (Hib) (one of the 6 capsular types) is responsible for more than 90% of the invasive or systemic infections.
Infections that can be caused by the Hib bacterium are:
Meningitis (an infection of the tissue lining the brain and spinal cord that can lead to brain damage and deafness) Pneumonia (lung infection) Epiglottitis (a severe throat infection that causes swelling of the throat making it hard to breathe) Infections of the blood, joints, bones, and covering of the heart (pericardium) Hib disease is a significant public health concern in many parts of the world; the H. Influenzae type b bacterium can cause a potent form of the disease in around 3 million people every year. Another rising fear is the increasing resistance of the Hib bacteria to antibiotic agents that have been reported from many parts of the world. This can be prevented if the Hib vaccine is used. Thus far, the Hib vaccine has been a big boon to society by cutting down the number of invasive Hib disease cases by more than 99%.
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The Hib vaccine is an inactivated vaccine. It is made chemically by bonding the polysaccharide called polyribisylribitol phosphate or PRP (that makes up the surface capsule of the bacterium) to a carrier protein. This process is known as conjugation, and hence the Hib vaccine is a polysaccharide conjugate vaccine.
Hib conjugate vaccines induce the production of protective circulating antibodies against PRP (anti-PRP) which protects the individuals from attack by the H. Influenzae type b bacteria. The vaccine also decreases the nasopharyngeal colonization of Hib, thereby reducing the chances of the spread of the infection.
The conjugate vaccine produces a better immune response as it has the advantage of being recognized by both the B cells and the T cells (B lymphocytes and T lymphocytes are white blood cells involved in immunity). The polysaccharide vaccine (that was used earlier and did not have the carrier protein) was only recognized by the B cells (this kind of interaction is called t-independent or TI), due to which the immunity may not have lasted for a long time.
Liquid or lyophilized preparations of the purified or synthetic sugar, PRP is conjugated either to the diphtheria toxoid (PRP-D), a diphtheria toxoid-like protein (PRP-HbOC), tetanus toxoid (PRP-T), or meningococcal outer membrane protein (PRP-OMP). These vaccines are called monovalent vaccines.
The conjugate vaccines differ from each other depending which protein carrier is used, the size of the polysaccharide, the method of chemical conjugation, and also the use of a spacer or a linking moiety between the PRP and protein carrier.
The Hib vaccine can also be given as part of a combination vaccine, where two or more types of vaccines are combined and administered as a single shot to protect against more than one disease. Hib combination vaccines contain diphtheria, tetanus, and pertussis (DPT-aP) vaccine, sometimes along with hepatitis B and/or the inactivated poliovirus vaccine, IPV.
Commercially, there are three types of monovalent vaccines and one combination vaccine licensed for use by the Food and Drug Administration (FDA).
All infants should receive Hib vaccine as part of their routine immunization. As Hib disease is rare in children older than five years, it is not routinely recommended for people five years or older. High-risk individuals include those with sickle cell disease (which damages the spleen), immunosuppressed from cancer chemotherapy, people 5 to 18 years old with HIV infection, and those who have undergone splenectomy (removal of the spleen), or a bone marrow transplant. These individuals have reduced immunity, which puts them at risk for Hib infection. The first primary dose can be given as early as 6 weeks. Any of the monovalent vaccines can also be used for older children and adults that need Hib vaccination.
The number of doses (either 2 or 3 primary doses) of the vaccine depend on the type of vaccine used
The recommended ages for the doses are:
First Dose: 2 months of age Second Dose: 4 months of age Third Dose: 6 months of age (if needed, depending on the brand of the vaccine) Final/Booster Dose: 12-15 months of age Children between 6 weeks and 2 years of age who have suffered from a Hib infection should also be administered the vaccine after recovery.
How is Hib Vaccine Given?
The Hib vaccine is given as an injection into the muscle.
Hib vaccine should not be given to the following individuals:
Those who had a severe allergic reaction to a previous dose of Hib vaccine or any part of the vaccine
Children less than six weeks of age
Persons who have a moderate or severe acute illness, who should receive the vaccine only after recovery from the illness.
Usually, there are no side effects associated with vaccination. Minor side effects include warmth, soreness, and redness at the injection site and mild fever. Serious problems are mainly allergic reactions to vaccine components.
If there are signs of a severe allergic reaction (hives, swelling of the face and throat), difficulty breathing, fast heartbeat, dizziness, and weakness), very high fever, or unusual behavior, please consult the doctor immediately.
Hib Immunization - News-Medical.net
Haemophilus influenza type b (Hib) is a bacterium that can cause serious invasive diseases, particularly in children. Hib usually affects children under the age of five years, but it can also cause illness in adults with certain medical conditions.
Before the introduction of routine Hib immunization, Hib was the most common cause of meningitis in children under the age of five in the US.
Hib meningitis causes death in as many as one in 20 children with the condition and one fifth of children who survive it suffer from permanent brain damage, seizure or loss of hearing. Today, Hib infections are rare and usually affect adults with underlying, chronic illnesses rather than children.
Other life threatening conditions the infection can cause include the following:
Epiglottitis – infection of the flap that lies over the opening to the trachea Pneumonia – lung infection Septicemia – blood infection Cellulitis – skin infection Septic arthritis – joint infection Pericarditis – infection of the fluid-filled sac that surrounds the heart Osteomyelitis – bone infection The Hib bacterium is spread through contact with mucus or droplets of fluid from an infected individual, usually through sneezing or coughing.
Hib (Haemophilus influenzae type b) vaccinePlay
Vaccination
Babies are offered the vaccine as a part of routine care and since its introduction, the rates of Hib diseases have fallen by almost 100%. There are several different brands of vaccine and depending on which one is used, babies receive either three or four separate doses.
The vaccine should not be given to any child aged under 6 weeks and the doses that are usually recommended are as follows:
First dose at two months of age Second at four months Third at six months of age (if required, depending on brand) Booster at 12 to 15 months The vaccine is administered as part of a combination vaccine, which means two or more different types of vaccine are given in one shot to protect against more than one illness.
The vaccine is not usually required for people older than five years, although older children may be vaccinated if they have asplenia or sickle cell disease and are due to undergo an operation to remove the spleen.
People may also be vaccinated after having had a bone marrow transplant or if they are HIV positive. People who are only mildly ill can receive the vaccine, but individuals who are moderately or seriously unwell are advised to wait until they have recovered.
Risks associated with vaccination
As is the case with any medication, the Hib vaccine is associated with the risk of side effects. These are usually mild and resolve independently, although, in rare cases, the side effects are severe. Usually, people who receive the vaccine do not experience any problems.
However, mild problems that may occur include fever, redness, swelling and warmth at the injection site. These problems usually start soon after administration of the vaccine and last up to two or three days.
Although severe allergic reactions to the vaccine are very rare and estimated to occur in less than one in a million cases, there is a very remote risk of such reactions occurring. Anybody who has previously experienced a life-threatening reaction following a previous Hib shot should not be given the injection. The person administering the shot should be made aware of any severe allergies.
Signs of a severe allergic reaction include the following:
Swelling of the face and throat Hives Breathing difficulty Rapid heart rate Weakness Feeling dizzy If a severe allergic reaction is suspected, the person should be taken to the nearest hospital and the reaction reported to the Vaccine Adverse Event Reporting System, a surveillance system that has been set up to help identify any safety issues with vaccines.
Further Reading
Study Finds Aluminum In Childhood Vaccines Not Linked To Long-Term Health Risks
Recent research confirms that aluminum in childhood vaccines does not increase the risk of autoimmune, allergic or neurodevelopmental disorders.
Based on findings from a nationwide study recently published in the Annals of Internal Medicine, it was found out of nearly 1.2 million children that early childhood exposure to aluminum in vaccines is not linked to the increased the risk of autoimmune, allergic or neurodevelopmental disorders.
Aluminum-based adjuvants are widely used in non-live vaccines to boost the immune response by binding vaccine antigens. Common early childhood vaccines containing aluminum include those for diphtheria, tetanus, pertussis, Haemophilus influenzae type b (Hib), pneumococcal conjugate vaccine (PCV) and hepatitis A and B. While these vaccines have been administered safely worldwide for decades, concerns persist about potential harms.
Animal studies have also suggested that aluminum exposure could have neurotoxic effects or increase the risk of autoimmune and atopic disorders, but human evidence is limited. Most existing research relies on preclinical models, ecological studies or small observational studies, leaving uncertainty about long-term effects.
The CDC noted that all adjuvanted vaccines are rigorously tested in clinical trials and continuously monitored post-licensure.
Another recent study looked at 327,000 children in the U.S. To see if aluminum in vaccines was linked to persistent asthma. The study found a potential link but limitations as well.
For example, it did not include children who developed asthma very early, other risk factors for asthma were not fully measured and the effect was small. Because of this, the study cannot prove that aluminum causes asthma.
The CDC and the AAP both noted these findings do not change vaccine recommendations, though they support more research on rare health outcomes.
In the Internal Medicine study, authors mentioned the Danish childhood vaccination program, in place since 1943, offers recommended vaccines free to all children, achieving coverage of 94% to 97% in the first two years of life. Over the past 25 years, policy changes, including the introduction of pneumococcal vaccines, substitutions of diphtheria-tetanus-pertussis formulations and updated vaccine versions, have resulted in varying aluminum exposure across birth cohorts.
Using Danish nationwide health registries, researchers examined whether cumulative aluminum exposure in the first two years of life is associated with chronic autoimmune, atopic or allergic, and neurodevelopmental disorders in children born between 1997 and 2018, followed through 2020.
Researchers conducted a cohort of all children born in Denmark from January 1, 1997, to December 31, 2018, using the Medical Birth Registry, which includes birth details, maternal characteristics and personal identifiers. These sources provided vaccination records, hospital diagnoses and potential confounders, such as preterm birth, household income and maternal medical history.
Children were included if they were alive at age 2, had not emigrated, had no major congenital or preexisting conditions, and had plausible vaccination records.
Aluminum exposure was calculated from all childhood vaccines received by age 2, including DTaP-IPV/Hib and pneumococcal vaccines, with aluminum content per dose ranging from 0.125 to 1 mg. Outcomes included 50 disorders—autoimmune, atopic or allergic and neurodevelopmental—identified through hospital records or prescription fills.
Children were followed from age 2 until age 5, death or loss to follow-up. Cox proportional hazards models estimated hazard ratios per 1-mg increase in aluminum, adjusting for multiple child and maternal factors. Sensitivity analyses examined age, sex, follow-up duration and exposure categorization.
The study included 1,224,176 children (48.8% female) born between 1997 and 2018, with most receiving at least one aluminum-adsorbed vaccine before age 2. Total aluminum exposure varied by birth year, with a median of 3 mg (range, 0–4.5 mg). Immediate characteristics were generally similar across exposure groups, though children with lower aluminum exposure had slightly lower household income and fewer general practitioner visits, while those with higher exposure more often had mothers with psychiatric disorders or diabetes.
Across the 24-year study period, cumulative aluminum exposure from early childhood vaccination was not associated with increased risk of autoimmune, atopic or neurodevelopmental disorders. For the combined outcome groups, adjusted hazard ratios per 1-mg increase in aluminum exposure were 0.98 (95% CI, 0.94–1.02) for autoimmune disorders, 0.99 (CI, 0.98–1.01) for atopic or allergic disorders, and 0.93 (CI, 0.90–0.97) for neurodevelopmental disorders. Individually analyzed outcomes—including asthma, atopic dermatitis, autism spectrum disorder and ADHD—also showed hazard ratios mostly below or near 1.0, with upper confidence limits largely incompatible with even small increases in risk.
Secondary analyses stratified by sex, birth year or exposure levels and extended follow-up to age 8 years yielded similar results.
Based on study results, many strengths were indicated. Some of these include its large, population-based design spanning 24 years, comprehensive outcome assessment across 50 chronic disorders and detailed connection to the Danish National Health Service Register, which supports accurate exposure data.
Limitations include the lack of randomization, potential residual confounding from unmeasured factors and temporal trends in vaccination and disease prevalence. Additionally, some disorders were rare or diagnosed later in childhood, limiting individual analyses.
The authors suggest that aluminum-adsorbed vaccines appear safe with respect to the outcomes studied, though continued monitoring and additional research on rarer outcomes or exposures outside the studied range remain warranted.
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