Impact of vaccine herd-protection effects in cost-effectiveness analyses of childhood vaccinations. A quantitative comparative analysisReport as inadecuate




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Background

Inclusion of vaccine herd-protection effects in cost-effectiveness analyses CEAs can impact the CEAs-conclusions. However, empirical epidemiologic data on the size of herd-protection effects from original studies are limited.

Methods

We performed a quantitative comparative analysis of the impact of herd-protection effects in CEAs for four childhood vaccinations pneumococcal, meningococcal, rotavirus and influenza. We considered CEAs reporting incremental-cost-effectiveness-ratios ICERs per quality-adjusted-life-years QALY gained; per life-years LY gained or per disability-adjusted-life-years DALY avoided, both with and without herd protection, while keeping all other model parameters stable. We calculated the size of the ICER-differences without vs with-herd-protection and estimated how often inclusion of herd-protection led to crossing of the cost-effectiveness threshold of an assumed societal-willingness-to-pay of $50,000 for more-developed countries or X3GDP-capita WHO-threshold for less-developed countries.

Results

We identified 35 CEA studies 20 pneumococcal, 4 meningococcal, 8 rotavirus and 3 influenza vaccines with 99 ICER-analyses 55 per-QALY, 27 per-LY and 17 per-DALY. The median ICER-absolute differences per QALY, LY and DALY without minus with herd-protection were $15,620 IQR: $877 to $48,376; $54,871 IQR: $787 to $115,026 and $49 IQR: $15 to $1,636 respectively. When the target-vaccination strategy was not cost-saving without herd-protection, inclusion of herd-protection always resulted in more favorable results. In CEAs that had ICERs above the cost-effectiveness threshold without herd-protection, inclusion of herd-protection led to crossing of that threshold in 45% of the cases. This impacted only CEAs for more developed countries, as all but one CEAs for less developed countries had ICERs below the WHO-cost-effectiveness threshold even without herd-protection. In several analyses, recommendation for the adoption of the target vaccination strategy depended on the inclusion of the herd protection effect.

Conclusions

Inclusion of herd-protection effects in CEAs had a substantial impact in the estimated ICERs and made target-vaccination strategies more attractive options in almost half of the cases where ICERs were above the societal-willingness to pay threshold without herd-protection. More empirical epidemiologic data are needed to determine the size of herd-protection effects across diverse settings and also the size of negative vaccine effects, e.g. from serotype substitution.



Author: Marisa Holubar , Maria Christina Stavroulakis , Yvonne Maldonado, John P. A. Ioannidis, Despina Contopoulos-Ioannidis

Source: http://plos.srce.hr/



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