Rebound increase in Hib incidence starting to emerge
A rebound increase in the incidence of Hib (Haemophilus influenzae type b) disease has been reported in adults.
Routine infant immunisation with Hib was introduced in October, 1992.
Adult Hib infections decreased to a low in 1998, probably as a result
of “herd” immunity. But in 2002–03 Hib infections in
those aged 15 years and over increased to pre-vaccine levels.
The increase in adult Hib infections is
associated with lower antibody levels and may be due to the reduced opportunities
for
natural boosting of immunity, say workers from the Health Protection
Agency Communicable Disease Surveillance Centre, who recorded the data.
They conclude that childhood immunisation programmes may have unexpected
effects on the epidemiology of disease in older age groups.
The researchers also note increasing cases of Hib infection in children
since 1998, ascribing lower than expected protection from vaccines, use
of less immunogenic, combination vaccines in 2000–01 plus the diminishing
impact of a “catch up” campaign. |
The
Pharmaceutical Journal
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