Cost-effectiveness and programmatic benefits of maternal vaccination against pertussis in England

Background: Maternal pertussis immunisation was introduced during the pertussis resurgence in England in 2012 as a temporary measure to protect infants too young to be vaccinated. The programme was shown to be safe and highly effective. However, continuation of maternal vaccination as a routine programme requires a cost-effectiveness analysis. Method: The estimated prevented disease burden among mothers and their infants was obtained assuming 89% (95% CI: 19%-99%) vaccine efficacy for mothers and 91% (95% CI: 84%-95%) for infants. Future incidence was projected based on the disease rates in 2010-2012, including the four-year cycle of low and high incidence years. Full probabilistic sensitivity analysis was performed for different scenarios. Results: Assuming a vaccine coverage of 60%, there were 1650 prevented hospitalisations in infants (3.5% discounting, the first 10 years), including 55-60 deaths and ~20,500 cases among mothers, of which around 1800 would be severe. The annual costs of the programme are £7.3 million assuming a price of £10 per dose and £9.4 million assuming £15 per dose. Using discounting of 3.5%, a 200 year time horizon and a price of £10 per dose (+£7.5 administration costs) only 25% of the iterations were below £30,000 per QALY. Using a 35% higher incidence resulted in 88% of the scenarios below this threshold. Assuming that the incidence remains at the level at the height of 2012, then the programme would be highly cost effective, with an ICER of £16,865 (£12,209-£25,976; price of £10 and 3.5%/3.5% discounting). Conclusion: Maternal vaccination is effective in preventing severe illness and deaths in infants but the cost-effectiveness of the programme is highly dependent on future incidence which is necessarily uncertain. However, the duration and magnitude of protection against transmission afforded by the current acellular vaccines is also uncertain as are the associated effects on future herd immunity. The direct protection offered by the maternal dose provides the only certain way of protecting vulnerable infants from birth.