Vaccine programmes must consider their effect on general resistance

Global health leaders have committed to making 2010-19 the decade of vaccines, with the aim of ensuring that lifesaving vaccines are available globally. The Bill and Melinda Gates Foundation pledged $10bn (£6.5bn; €8bn) to the new decade,1 which was established in recognition of the astonishing technological progress in developing new vaccines and our ethical obligation to make these vaccines available to all children in the poorest countries of the world.1 2 ^w1-8 The ultimate goal is to save lives, and vaccination programmes measure potential impact in terms of the lives saved.1 2 ^w1

Surprisingly, therefore, there are few observational studies and virtually no randomised clinical trials documenting the effect on child mortality of any of the existing vaccines. A notable exception is the high titre measles vaccine, which was withdrawn because an interaction with diphtheria-tetanus-pertussis (DTP) vaccine resulted in a 33% (95% confidence interval 2% to 73%) increase in mortality among children aged 4-60 months in several west African randomised trials.3 ^w9 Among the newer vaccines, conjugate pneumococcal vaccine has been found to be associated with an 11% (−1% to 21%) reduction in mortality in a meta-analysis.4

The lack of data on mortality is not considered a problem. If a vaccine is shown to produce immunity against a specific disease, the effect on survival is estimated using the burden of disease, and the efficacy and the coverage of the specific vaccine. For example, if rotavirus causes 527 000 annual deaths, 90% occurring in low income …