Over a million children in low and middle income countries die every year from infectious diseases such as diarrhoea and pneumonia.
There are vaccines available that could reduce this burden dramatically, but in many countries there are concerns about the cost. Policy makers need information that they can defend about the likely impact of a new vaccine in order to make a case for its introduction.
In 2007 Andrew Clark, lecturer and Colin Sanderson, professor of operational research in health care, with Ulla Griffiths, senior lecturer in health economics, began developing a computer-based but accessible decision-support model that estimates the health impact and cost effectiveness of the Haemophilus influenza type b (Hib) vaccine. The primary aim was to help national policy makers to estimate the benefits of this new vaccine for their own country in terms of mortality, morbidity and disability-adjusted life-years.
The next step was to extend this model so that it could be used for pneumococcal and rotavirus vaccines as well, and in 2008 it was adopted for use in a Pan-American Health Organisation initiative promoting evidence-based decision-making. A human papillomavirus vaccine model was developed in 2011. These models have now been used by policy-makers and analysts to support vaccine choices in 16 countries in the Americas, and 12 countries elsewhere.
Since 2008, Clark and Sanderson have also been developing models to support World Health Organization (WHO) policy about vaccine schedules, which set out the numbers of doses of vaccine each child should have, and at what ages. The 3-vaccine model was again extended to address the effects of possible changes to the recommended schedules, and of tackling vaccination delays. This piece of work has also involved the re-analysis of survey data from 45 countries on age at vaccination, and reviews of the epidemiological data on age at preventable disease in unvaccinated populations.
One of the points at issue was a recommended maximum age for the first dose of rotavirus vaccine. The concern was that if the vaccine was given when the child was more than about 15 weeks old, there was a small risk of a dangerous complication. However the researchers found that if this age limit was removed, the lives saved by late vaccination would far outweigh any potential adverse effects. As a result the WHO changed its recommendation.
The schedules model was also used to help evaluate the public health impact of alternative schedules for the pneumococcal vaccine in 2011 and the Hib vaccine in 2012. WHO’s senior advisory group on immunisation, welcomed and endorsed the model as something that would help national decision-makers choose schedules that were right for their circumstances.
With support from the Pan American Health Organization and WHO the School launched a website to provide vaccine data to developing countries. The site is designed for policy makers and analysts to provide evidence of the health and financial benefits of vaccines.