Economic evaluation using dynamic transition modeling of ebola virus vaccination in lower-and-middle-income countries

Abstract

Background

With the increasing occurrence of infectious diseases in lower-and-middle-income countries (LMICs), emergency preparedness is essential for rapid response and mitigation. Economic evaluations of mitigation technologies and strategies have been recommended for inclusion in emergency preparedness plans. We aimed to perform an economic evaluation using dynamic transition modeling of ebola virus disease (EVD) vaccination in a hypothetical community of 1,000 persons in the Democratic Republic of Congo (DRC).

Method

Using a modified SEIR (Susceptible, Exposed, Infectious, Recovered, with Death added [SEIR-D]) model that accounted for death and epidemiological data from an EVD outbreak in the DRC, we modeled the transmission of EVD in a hypothetical population of 1,000. With our model, we estimated the cost-effectiveness of an EVD vaccine and an EVD vaccination intervention.

Results

The results showed vaccinating 50% of the population at risk prevented 670 cases, 538 deaths, and 22,022 disability-adjusted life years (DALYs). The vaccine was found to be cost-effective with an incremental cost-effectiveness ratio (ICER) of $95.63 per DALY averted. We also determined the minimum required vaccination coverage for cost-effectiveness to be 40%. Sensitivity analysis showed our model to be fairly robust, assuring relatively consistent results even with variations in such input parameters as cost of screening, as well as transmission, infection, incubation, and case fatality rates.

Conclusion

EVD vaccination in our hypothetical population was found to be cost-effective from the payer perspective. Our model presents an efficient and reliable approach for conducting economic evaluations of infectious disease interventions as part of an emergency preparedness plan.

PLAIN LANGUAGE SUMMARY

Infectious diseases affect lower-and-middle-income (LMIC) countries, with their limited resources, disproportionately more. This is certainly the case for ebola virus disease (EVD), a rare, severe, and mostly fatal disease. Vaccination is now available, but whether it is cost-effective remains an open question. We evaluated its cost-effectiveness by modeling the spread of EVD in a hypothetical population of 1000 persons. Using data from an EVD outbreak in the Democratic Republic of Congo (DRC), we estimated how many of persons susceptible to infection were exposed to the virus, became infected, recovered, or died. We did so for two scenarios: vaccinating versus not vaccinating enough people to achieve herd immunity. We assumed vaccinating 50% of the people and estimated how many infections, deaths, and disability-adjusted life years (DALY; the loss of the equivalent of a year of full health) would be prevented by vaccination. Our cost-effectiveness metric was the incremental cost of preventing one DALY.

The outcomes of vaccination offset the additional costs. Vaccinating 50% of the population of 1000 cost an additional $2,081,358 but prevented 670 infections, 538 deaths, and 22022 DALYs. Preventing one DALY cost $95.63. This is very cost-effective as it is less than the gross domestic product (GDP) per capita for the DRC of $556.81. Vaccination below 40% of the population was less cost-effective, was most cost-effective at the herd immunity threshold of 45.3%, beyond which there were diminishing returns. Summarized, vaccination against EVD is clinically very effective and certainly worth the additional cost.

Keywords:

• Dynamic modeling
• emergency preparedness
• ebola virus disease
• vaccination
• cost-effectiveness

JEL Classification Codes:

• I15
• I1
• I
• I11

View addendum:

Comparative value-based pricing of an Ebola vaccine in resource-constrained countries based on cost-effectiveness analysis

Transparency

Declaration of funding

This study received no funding.

Declaration of financial/other interests

IA holds equity in Matrix45, LLC, which provides research and consulting services to, among others, the pharmaceutical industry. Matrix45, LLC previously was contracted by Celgene for work unrelated to the subject of this Technical Note. By company policy, associates of Matrix45, LLC cannot provide services to nor receive compensation independently from sponsor organizations. IA has no other disclosures related to the work reported herein. All other authors have no disclosures related to the work reported herein. Peer reviewers on this manuscript have no relevant financial or other relationships to disclose.

Authors contributions

MOK and MH contributed to study design, collection, analyses and interpretation of data, revision, and final approval of the manuscript. DJR and BE contributed to revision and final approval of the manuscript. IA contributed to study design, revision, and final approval of the manuscript.

Acknowledgements

No assistance in the preparation of this article is to be declared.

Previous presentations

This study was never presented previously.