Vaccines for preventing severe Haemophilus influenzae type b (Hib) infections in people with sickle cell disease

Review question

We reviewed the available evidence from randomised controlled trials about how effective and safe Haemophilus influenzae type b (Hib) conjugate vaccines are for people with sickle cell disease.

Background

People with sickle cell disease are at high risk of infection from Hib, which was responsible for a high death rate in children under five years of age before Hib conjugate vaccination was introduced in high-income countries. In African countries, where coverage for this vaccination is extremely low, Hib remains one of the most common causes of bacteraemias (bacteria in the blood) in children with sickle cell disease. Another Cochrane review on conjugate vaccines for preventing Hib infections in children under five years of age has shown that Hib conjugate vaccines were safe and effective but it did not specifically look at children with sickle cell disease, who have a high risk of this infection.

Search date

The evidence is current to: 23 November 2015.

Study characteristics

We did not find any randomised controlled trials comparing Hib conjugate vaccines with placebo ('dummy' treatment) or no treatment in people with sickle cell disease.

Key results and quality of the evidence

There are no randomised controlled trials of this vaccine in people with sickle cell disease. However, there has been a dramatic decrease in the occurrence of severe Hib infections in children with sickle cell disease living in high-income countries since the vaccination has been included in childhood immunisation schedules. Therefore, including universal Hib conjugate vaccination in low-income countries may improve the survival of children with sickle cell disease. There is not enough data to allow us to assess the potential effect of Hib vaccination in unvaccinated adults with sickle cell disease. Future trials should assess the ideal Hib immunisation schedule in children and adults with sickle cell disease.

Authors' conclusions: 

There has been a dramatic decrease in the incidence of invasive Haemophilus influenzae type b infections observed in the post-vaccination era in people with sickle cell disease living in high-income countries. Therefore, despite the absence of evidence from randomised controlled trials, it is expected that Haemophilus influenzae type b conjugate vaccines may be useful in children affected with sickle cell disease, especially in African countries where there is a high prevalence of the disease. The implementation of childhood immunisation schedules, including universal Haemophilus influenzae type b conjugate vaccination, may substantially improve the survival of children with sickle cell disease living in low-income countries. We currently lack data to evaluate the potential effect of Haemophilus influenzae type b vaccination among unvaccinated adults with sickle cell disease. Further research should assess the optimal Hib immunisation schedule in children and adults with sickle cell disease.

Read the full abstract...
Background: 

People affected with sickle cell disease are at high risk of infection from Haemophilus influenzae type b. Before the implementation of Haemophilus influenzae type b conjugate vaccination in high-income countries, this was responsible for a high mortality rate in children under five years of age. In African countries, where coverage of this vaccination is still extremely low, Haemophilus influenzae type b remains one of the most common cause of bacteraemias in children with sickle cell disease. The increased uptake of this conjugate vaccination may substantially improve the survival of children with sickle cell disease.

Objectives: 

The primary objective was to determine whether Haemophilus influenzae type b conjugate vaccines reduce mortality and morbidity in children and adults with sickle cell disease.

The secondary objectives were to assess the following in children and adults with sickle cell disease: the immunogenicity of Haemophilus influenzae type b conjugate vaccines; the safety of these vaccines; and any variation in effect according to type of vaccine, mode of administration (separately or in combination with other vaccines), number of doses, and age at first dose.

Search strategy: 

We searched the Cochrane Cystic Fibrosis and Genetic Disorders Group's Haemoglobinopathies Trials Register, compiled from electronic database searches and handsearching of journals and conference abstract books. We also contacted relevant pharmaceutical companies to identify unpublished trials.

Date of last search: 23 November 2015.

Selection criteria: 

All randomised and quasi-randomised controlled trials comparing Haemophilus influenzae type b conjugate vaccines with placebo or no treatment, or comparing different types of Haemophilus influenzae type b conjugate vaccines in people with sickle cell disease.

Data collection and analysis: 

No trials of Haemophilus influenzae type b conjugate vaccines in people with sickle cell disease were found.

Main results: 

There is an absence of evidence from randomised controlled trials relating to the subject of this review.

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