ABSTRACT

Introduction

Prior to implementation of Haemophilus influenzae type b (Hib)-conjugate vaccination programs in the 1990s, Hib was the commonest cause of bacterial meningitis in children aged <5 years. While the burden of all Hib disease has significantly decreased in the post-vaccination era, Hib still accounted for >29,000 deaths worldwide in children aged <5 years in 2015.

Areas covered

We reviewed literature data on the most widely used Hib vaccines and vaccination strategies which led to the global prevention and control of Hib disease and aim to highlight important factors for continued disease control and elimination in the future.

Expert commentary

More than 90% of countries worldwide have implemented Hib-conjugate vaccination in their national immunization programs. Vaccines containing Hib polyribosylribitol phosphate (PRP) conjugated with tetanus toxoid (Hib-TT) are the most commonly used. Neisseria meningitidis outer membrane protein complex of PRP (Hib-OMP) is also used. Although the kinetics of the immune response varies with Hib vaccine and schedule used, high control of Hib disease was observed in all settings/scenarios. Further improving global Hib vaccination coverage may result in disease elimination.

Plain language summary

What is the context?

• Haemophilus influenzae is causing a variety of diseases, from otitis media and sinusitis to invasive disease (e.g. meningitis and pneumonia).

• H. influenzae type b (Hib) was the most common cause of bacterial meningitis in children <5 years of age, and especially among <2-year-olds. Even with appropriate treatment, up to 40% of children with bacterial meningitis can suffer permanent disabilities and up to 5% will die.

• The development of vaccines to protect against Hib disease has started in the late 1970s and has culminated with the licensure of 4 Hib conjugate vaccines, of which 2 are currently widely used.

What is new?

• In this review, we gathered evidence on the different Hib vaccines and vaccination strategies that have contributed to the global prevention and control of Hib disease.

• The review indicates:

• the incidence of Hib disease has decreased considerably due to the introduction of Hib vaccines in national immunization programs worldwide. However, Hib disease is not yet completely eradicated.

• the vaccines currently used offer protection against Hib over long periods of time.

• carriage of the pathogen by healthy individuals seem to be less frequent, but data are still needed to fully evaluate the impact of vaccination.

• other H. influenzae types are now more frequent.

Why is this important?

• Despite the huge success of Hib vaccination, continuous surveillance is needed to anticipate potential re-emergences and devise the best strategies for prevention and control of disease.

• Hib vaccination should be considered in the few countries who have not yet implemented it, to decrease associated morbidity and mortality.

介绍

在1990年代实施b型流感嗜血杆菌（Hib）结合疫苗接种计划之前，Hib是5岁以下儿童细菌性脑膜炎的最常见原因。尽管在疫苗接种后时代，所有Hib疾病的负担已显着降低，但2015年，Hib仍占全世界<5岁儿童的29,000多例死亡。

覆盖区域

我们回顾了有关最广泛使用的Hib疫苗和疫苗接种策略的文献数据，这些数据导致了全球对Hib疾病的预防和控制，并着重强调了今后继续控制和消除疾病的重要因素。

专家评论

全球超过90％的国家/地区已在其国家免疫计划中实施了Hib-缀合疫苗接种。最常用的疫苗是含有与破伤风类毒素（Hib-TT）结合的Hib聚核糖基核糖醇磷酸酯（PRP）的疫苗。还使用了脑膜炎奈瑟氏球菌的PRP外膜蛋白复合物（Hib-OMP）。尽管免疫应答的动力学随Hib疫苗和所用时间表的不同而变化，但在所有情况/情况下都可高度控制Hib疾病。进一步提高全球Hib疫苗接种覆盖率可能会消除疾病。