The role of immunisation in the prevention of hearing loss

The Expanded Programme of Immunisation represents one of the great public healthachievements of the last 50 years. In 1974, the programme established a core set of 6vaccines (BCG, diphtheria, tetanus, pertussis, polio, and measles) and a coverage targetof 90% by 1990. The contribution of immunisation to early childhood mortality anddisability has been substantial. With 20 vaccine preventable diseases now beingaddressed, immunisation will continue to reduce poor outcomes associated with infection(including hearing loss) throughout the world.To date, the largest gains in the prevention of severe to profound sensorineuralhearing loss have come from the measles and rubella vaccines, and the protein-conjugatedbacterial meningitis vaccines (targeting Hib, pneumococcal and mening-ococcaldisease). Most of the mild and moderate conductive hearing loss in the world is associatedwith otitis media. To some extent, OM is a vaccine preventable disease. In thefuture, the development of otitis media vaccines (or combinations of vaccines) thatreduce colonisation and protect against common respiratory bacterial and viral pathogenshas the potential to dramatically reduce the frequency of mild and moderate hearing lossin young children.The World Health Organization (WHO) estimates that around 4% of the world'spopulation has a hearing disability and 6% have a hearing impairment [1, 2]. Themajority of these individuals live in developing countries. In this setting, preventable ortreatable infection remains the most important cause of disease.In developed countries with comprehensive health systems, rates of acquired hearingimpairment in children should be decreasing [3]. Bacterial meningitis is on the decline [4]and chronic middle ear infections associated with permanent hearing loss is uncommon(affecting <1% of the population) [5]. The contribution of immunisation to theseimprovements has been substantial.Overall, the WHO estimates that around 50% of the burden of hearing impairment ispreventable [1]. In this chapter, we consider how much hearing impairment is preventedby immunisation and how this may change in the future. The overall benefits ofimmunisation have been widely applauded: ... "With the exception of safe water, noother modality, not even antibiotics, has had such an effect on mortality reduction..." [6,7]. However, the impact on specific disabilities (such as hearing impairment) is less clear.