Abstract:
A new mathematical model for the transmission dynamics and control of the Middle Eastern
respiratory syndrome (MERS), a respiratory virus caused by MERS-CoV coronavirus (and primarily
spread to humans by dromedary camels) that first emerged out of the Kingdom of Saudi Arabia (KSA)
in 2012, was designed and used to study the transmission dynamics of the disease in a human-camel
population within the KSA. Rigorous analysis of the model, which was fitted and cross-validated using the observed MERS-CoV data for the KSA, showed that its disease-free equilibrium was locally
asymptotically stable whenever its reproduction number (denoted by R0M) was less than unity. Using the fixed and estimated parameters of the model, the value of R0M for the KSA was estimated to
be 0.84, suggesting that the prospects for MERS-CoV elimination are highly promising. The model
was extended to allow for the assessment of public health intervention strategies, notably the potential
use of vaccines for both humans and camels and the use of face masks by humans in public or when in
close proximity with camels. Simulations of the extended model showed that the use of the face mask
by humans who come in close proximity with camels, as a sole public health intervention strategy, significantly reduced human-to-camel and camel-to-human transmission of the disease, and this reduction
depends on the efficacy and coverage of the mask type used in the community. For instance, if surgical masks are prioritized, the disease can be eliminated in both the human and camel population if at
least 45% of individuals who have close contact with camels wear them consistently. The simulations
further showed that while vaccinating humans as a sole intervention strategy only had marginal impact
in reducing the disease burden in the human population, an intervention strategy based on vaccinating
camels only resulted in a significant reduction in the disease burden in camels (and, consequently, in
humans as well). Thus, this study suggests that attention should be focused on effectively combating
the disease in the camel population, rather than in the human population. Furthermore, the extended model was used to simulate a hybrid strategy, which combined vaccination of both humans and camels
as well as the use of face masks by humans. This simulation showed a marked reduction of the disease burden in both humans and camels, with an increasing effectiveness level of this intervention, in
comparison to the baseline scenario or any of the aforementioned sole vaccination scenarios. In summary, this study showed that the prospect of the elimination of MERS-CoV-2 in the Kingdom of Saudi
Arabia is promising using pharmaceutical (vaccination) and nonpharmaceutical (mask) intervention
strategies, implemented in isolation or (preferably) in combination, that are focused on reducing the
disease burden in the camel population.
