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| HAEMOPHILUS INFLUENZAE TYPE B |
Disease
Haemophilus influenzae type b (Hib) is a common cause of bacterial pneumonia and meningitis and of a number of other serious and potentially life-threatening conditions, including epiglottitis, osteomyelitis, septic arthritis and sepsis in infants and older children.
Occurrence
Hib is estimated to cause at least 3 million cases of serious disease and hundreds of thousands of deaths annually, worldwide. Rarely occurring in infants under 3 months or after the age of 6 years, the disease burden is highest between 4 and 18 months of age. Hib is the dominant cause of sporadic (non-epidemic) bacterial meningitis in this age group, and is frequently associated with severe neurological sequelae despite prompt and adequate antibiotic treatment. In developing countries, it is estimated that 2–3 million cases of Hib pneumonia occur each year. The disease has practically disappeared in countries where routine vaccination of children is carried out. Therefore all children who are not updated, this vaccine should be offered as Hib vaccine has dramatically reduced the incidence of Hib meningitis in infants and nasopharyngeal colonization by Hib.
Risk for travellers
All unprotected children are at risk at least up to the age of 5 years.
Vaccine
Haemophilus influenzae type b (Hib) vaccine is made from capsular polysaccharide; and is available as single agent preparation for use in children, who did not receive it as a part of routine immunized programme. It is also conjugated with a protein such as tetanus toxoid to increase immunogenicity, especially in young children. Hib vaccines are also available as combination vaccines as DTP/Hib. DTPa/Hib, DTPa/IPV/Hib, DTP/Hep B/Hib, DTPa/Hep B/Hib, DTPa/IPV/Hep B/Hib. The studies using these combination vaccines show similar immune responses to all the components as compared to when given separately.
Haemophillus influenzae type b vaccine is a component of the primary course of childhood immunization and is given along with diphtheria, tetanus, pertussis schedule. For infants under 1 year, the course consists of 3 doses of a vaccine containing haemophillus influenzae type b component with an interval of 1 months between doses. A booster dose of haemophilus influenzae type b vaccine should be given at around 12 months of age.
Unimmunised children over 12 months need only 1 dose of Haemophilus influenzae type b vaccine.
The risk of infection falls sharply in older children and the vaccine is not normally required for children over 10 years. Haemophilus influenzae type b vaccine may be given to those over 10 years who are considered to be at increased risk of invasive H.influenzae type b disease (such as those with asplenia, sickle cell disease, immunodeficiency states, nephrotic syndrome and complement deficiency.
Asplenia or splenic dysfunction:
Haemophilus influenzae type b vaccine is recommended for patients with splenic dysfunction. Immunized adults and children over 1 year, who develop splenic dysfunction, should be given 1 additional dose of haemophilus influenzae type b vaccine. For elective splenectomy, the vaccine should ideally be given at least 2 weeks before surgery. Adults and children over 1 year who are not immunized against haemophilus influenzae type b, should be given 2 doses of haemophilus influenzae type b vaccine with an interval of 2 months between the 2 doses. However, children under 10 years, who are not immunized, should be immunized by giving 3 doses of the vaccine at 1 month interval. |
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