Middle East respiratory syndrome: obstacles and prospects for vaccine development

Abstract

The recent emergence of Middle East respiratory syndrome (MERS) highlights the need to engineer new methods for expediting vaccine development against emerging diseases. However, several obstacles prevent pursuit of a licensable MERS vaccine. First, the lack of a suitable animal model for MERS complicates the in vivo testing of candidate vaccines. Second, due to the low number of MERS cases, pharmaceutical companies have little incentive to pursue MERS vaccine production as the costs of clinical trials are high. In addition, the timeline from bench research to approved vaccine use is 10 years or longer. Using novel methods and cost-saving strategies, genetically engineered vaccines can be produced quickly and cost-effectively. Along with progress in MERS animal model development, these obstacles can be circumvented or at least mitigated.

Keywords: Coronaviridae; MERS-CoV; Middle East respiratory syndrome; Nidovirales; betacoronavirus; coronavirus; nidovirus.

Figure 1.

Hypothesized transmission of MERS-CoV from animal hosts to humans. (A) MERS-CoV is potentially transmitted by infected bats to African one-humped camels, which are often exported to the Arabian Peninsula. (B) Vaccination of one-humped camels could, therefore, prevent further transmission of the virus to humans and subsequent human-to-human transmission if one-humped camels are indeed the primary route of infection for humans.

Figure 2.

Estimation of major hospital costs affiliated with a MERS outbreak. Average cost per day per in-patient was multiplied by the median number of days for total cost per treatment. In-patient stay: US average of US$3145/day × 14 days median for a MERS in-patient = US$44,030.00; intensive care unit stay: ^†US$16,474 × 22 days = US$362,430; mechanical ventilation: ^†US$23,750 × 11.5 days = US$273,139; renal replacement therapy: US$3819 × 7 days = US$26,734; total: sum of in-patient costs after multiplying by the percentage required and adding the additional administrative costs of US$79,150 per in-patient = US$713,942. An in-patient requiring all interventions would incur expenses of more than US$785,000.

Figure 3.

Idealized vaccine development timeline from post-discovery to pre-regulatory submission. A simplified timeline illustrates the potential pitfalls encountered throughout the development process. Optimistic estimates for vaccine development from candidate selection to industrial production fall between 3.5 and 4 years, depending on the type of vaccine. After adding 2–3 years for research prior to candidate selection and 2–3 years for regulatory submission and licensure once a final formulation is in hand, total time is approximately 10 years. As discovery methods and bureaucratic processes and approvals are accelerating, the overall timeline could realistically shrink to 6–7 years.