A Model-Based Strategy on COVID-19 Vaccine Roll-out in the Philippines

Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2. Millions of people have fallen sick, and some have died due to this affliction that has spread across the globe. The current pandemic has disrupted normal day-to-day human life, causing a profound social and economic burden. Vaccination is an important control measure that could significantly reduce the incidence of cases and mortality if properly and efficiently distributed. In this work, an age-structured model of COVID-19 transmission, incorporating an unreported infectious compartment, is developed. Three age groups are considered, namely: young (0-19 years), adult (20-64 years), and elderly (65+ years). The transmission and reporting rates are determined for each group by utilizing the number of COVID-19 cases in the National Capital Region in the Philippines. Optimal control theory is employed to identify the best vaccine allocation to different age groups. Further, three different vaccination periods are considered to reflect phases of vaccination priority groups: the first, second, and third account for the inoculation of the elderly, adult and elderly, and all three age groups, respectively. This study could guide in making informed decisions in mitigating a population-structured disease transmission under limited resources.