Haemophilus influenzae can cause serious invasive disease, particularly in young children
- invasive disease is usually caused by encapsulated strains of the organism
- there are six typeable capsular serotypes (a - f) are known to cause disease
- before the introduction of vaccination, type b (Hib) was the prevalent strain
Hib vaccine offers protection against the capsulated form of Hib that may cause:
- meningitis
- acute epiglottitis
- pneumonia
- septic arthritis
- cellulitis
Hib-containing vaccines are made from capsular polysaccharide that has been extracted from cultures of Hib bacteria
- the polysaccharide is linked (conjugated) to a protein - in the UK, Hib vaccines have been used that have been conjugated with either CRM197 (a non-toxic variant of diphtheria toxin) or tetanus toxoid
- conjugation increases the immunogenicity, especially in young children in whom the plain polysaccharide vaccines are not immunogenic
The Hib vaccine is given as part of a combined product:
- diphtheria/tetanus/acellular pertussis/inactivated polio vaccine/ Haemophilus influenzae type b (DTaP/IPV/Hib/Hep B) vaccine
- Hib/MenC conjugate
Primary immunisation in infants and children under 10 years of age:
- consists of three doses of a Hib-containing product with an interval of one month between each dose
- DTaP/IPV/Hib/Hep B is recommended for all children from two months up to ten years of age
- although one dose of Hib vaccine is effective from one year of age, three doses of DTaP/IPV/Hib should be given to children who have either not been immunised or who have not completed a primary course, in order to be fully protected against diphtheria, tetanus, pertussis and polio
- if the primary course is interrupted it should be resumed but not repeated, allowing an interval of one month between the remaining doses
- children of one to ten years of age who have completed a primary course of diphtheria, tetanus, pertussis and polio but have not received Hib-containing vaccines, should receive a single dose of Hib/MenC vaccine
Re-inforcing immunisation:
- a single reinforcing (booster) dose of Hib/MenC is recommended at 12 months for children who have received a complete primary course of three Hib-containing vaccines injections
- this booster should be given one month before pneumococcal conjugate and MMR vaccines.
Notes:
- non-encapsulated strains are mainly associated with respiratory infections such as exacerbation of chronic bronchitis and otitis media
- non-typeable encapsulated strains can occasionally cause invasive disease.
Reference:
- Immunisation Against Infectious Disease - "The Green Book".Chapter 16 Haemophilis influenzae type B (Hib) (April 2019)