Are Hib booster vaccinations redundant?

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O Bohm and R von Kries (July 5, p 68)1Bohm O von Kries R Are Hib booster vaccinations redundant?.Lancet. 1997; 350: 68Summary Full Text Full Text PDF PubMed Scopus (2) Google Scholar argue that in populations with different vaccination programmes and coverage from those in the UK, it may be unwise to omit a booster dose of Haemophilus influenzae type b (Hib) vaccine. In our study, we concluded that children who received three primary doses of Hib vaccine were highly protected until school-age without a booster dose in the second year of life.2Booy R Heath PT Slack MPE Begg N Moxon ER Vaccine failures after primary immunisation with Haemophilus influenzae type-b conjugate vaccine without booster.Lancet. 1997; 349: 1197-1202Summary Full Text Full Text PDF PubMed Scopus (108) Google Scholar In addition to the use of a highly immunogenic vaccine (PRP-T) and high vaccine coverage (>90% complete three doses in the first year of life), the “catch up” strategy of one dose for children aged 12–48 months for the first year of the vaccine programme is also likely to have contributed to the success of the UK programme. Where fewer than three doses of Hib vaccines, such as PRP-T, HbOC, and PRP-D, are given in the first year of life, a lower protective efficacy can be predicted from antibody responses, as shown in a subgroup analysis of the UK surveillance data. It is not surprising that analysis of the German case-control study also revealed two doses of vaccine to be suboptimum.3Von Kries R Bohm O Windfuhr A Haemophilus influenzae b vaccination: the urgency for timely vaccination.Eur J Pediatr. 1997; 156: 282-287Crossref PubMed Scopus (31) Google Scholar They observed ten cases of possible Hib disease in children older than 18 months who had received two or three doses of vaccine in the first year of life and no booster. However, only one of these was a child who had received three primary doses; thus the efficacy of three doses with no booster is likely to be high. The approach we favour is the use of three primary doses rather than the addition of an 18-month booster, which will result in protection through the age of greatest susceptibility (6–12 months). As a public-health strategy this approach also has the advantage that parents are more likely to comply with a schedule completed in early infancy than one completed in the second year of life. The issues of the most appropriate Hib vaccine and schedule to use are important, especially in countries that do not yet have programmes of vaccination against Hib. The experience in different countries provides useful insights. For example, in the Republic of Ireland, routine immunisation is with HbOC: no booster dose is provided and a catch-up programme was used for the first year. Coverage is estimated to be about 75%, but disease incidence has fallen by more than 90%, and the calculated vaccine efficacy is similar to that estimated for the UK (unpublished observation, J Fogarty). In Iceland, disease has been almost eliminated with the least immunogenic Hib conjugate vaccine, PRP-D. The explanation may well be the high vaccine coverage achieved (>90%) and a schedule consisting of three doses in the first year of life together with a booster dose at 18 months.4Jonsdottir KE Hansen H Arnorsson VH Laxdal P Stefansson M Immunization against Haemophilus influenzae type b in Iceland: results after six years use of PRP-D (ProHIBiTR).Icelandic Med J. 1996; 82: 32-38Google Scholar A European Community funded project, coordinated by the Public Health Laboratory Service Communicable Disease Surveillance Centre, in London, UK, with partners in six European countries and Australia, is attempting to compare and contrast experience with Hib disease and control.