1009 Respiratory administration of measles vaccine

In 2008 the World Health Assembly reaffirmed the goal to reduce measles mortality by >90% vs 2000 rates and gave a target date of 2010. The WHO Executive Board has also instructed the organization to explore the feasibility of global eradication of the disease. In South Africa one has to wonder about these targets given that there has recently been an outbreak of measles in Gauteng and the Western Cape is currently experiencing an outbreak. Immunisation programmes are obviously under the spotlight, and attention is being focused on respiratory administration of the vaccine. The approach is not new, with comparative studies of injectable vs aerosol vaccine having appeared almost 30 years ago. Meta-analyses have included up to 16 studies and results show that delivery via the respiratory route is at least as immunogenic as the same vaccine delivered subcutaneously in children aged 10-36 months. Furthermore, the respiratory route has been shown to be better for boosting responses in those who are seropositive, and in infants, mucosal administration is less likely to be blocked by maternal antibodies than is subcutaneous vaccine. Adverse reactions do not appear to be different between the administration routes, however there is concern about safety in high-risk groups such as children with asthma or immunocompromise as in HIV/AIDS. Delivery system development is under way and there is progress in overcoming shortcomings of early devices. Currently nasal sprays, dry powders and nebulisers are being investigated, with the WHO involved as coordinator of a Measles Aerosol Project that will assess at least three methods for delivery of reconstituted aerosol vaccine, and a dry powder vaccine might also be assessed. Products will be tested in routine and mass immunization programmes. An Indian study currently underway could see a licensed device as early as 2011. An important aspect to be studied in all these initiatives is clinical effectiveness: while immunogenicity has been shown to be at least equal to that of injected vaccine, data relating to clinical effectiveness are lacking.

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