Modelling the impact of vaccination on cholera transmission dynamics under stratified populations and seasonality.

Different types of oral cholera vaccines (OCVs) are currently available in the global market to combat cholera epidemic. In most of developing countries, there is comparatively limited deployment of vaccination programs. In this study, we develop a non-linear deterministic mathematical model to investigate the dynamics of cholera in the presence of vaccination under stratified population, and taking into account the seasonality of the disease dynamic. The model stratifies the total population into two strata based on level of exposure or individuals risk status. We use reported cholera data to estimate the values of model parameters using the least square method together with the fminsearch function in the MATLAB optimization toolbox. Sensitivity analysis was performed to identify the impact of vaccination on cholera transmission dynamics. Numerical results show that the reproduction numbers were 3.35 and 2.6 in more and less exposed population, respectively, with an average value of the whole population equal to 2.98. Specifically, our findings indicate that at least 70 % of the most exposed population needs to be vaccinated to halt transmission within that group, while a minimum of 62 % of the less exposed population must be vaccinated to halt transmission in this population. We further observe that the vaccination rate significantly impact the amplitude of the epidemic curves. Our findings suggest that vaccination of susceptible population stratified with a certain priority (e.g., level of exposure or individual's risk status) against the disease can reduce the transmission of cholera, potentially slowing the spread of the bacteria in a population.