Mathematical modelling to assess the impacts of cross-border travel controls of Covid-19 pandemic in Thailand

Abstract

Four components of intervention strategies related to Thailand’s cross-border travel control are (1) assessing risk of infection from departure country, (2) pre-departure screening and requiring of vaccination certificate, (3) point of entry screening and validation of the requirements, and (4) compliance to Thailand’s national quarantine strategies. A cross-border travel control model was developed, incorporating the transmission dynamics of COVID-19. From Our-World-In-Data (OWID) extracted on January 9th, 2022, this research study applied cluster analysis to derive three distinct groups of countries based on vaccination coverage, infection rates and test positivity. For modelling, 863 imported cases per 10 5 travelers per week were estimated in a no intervention scenario. For the optimal strategy where all interventions were implemented by the country of origin i.e., a combination of requiring of vaccination certificate, in a cluster with low infection rate, and immediate testing before departing, the model estimated 157 imported cases per 10 5 travelers per week. Adding workload to Thailand by providing 14-day quarantine will further reduce the number of imported cases to 5 per 10 5 travelers per week. Nevertheless, the model requires adjustments to its clustering algorithm technique to real-time data to enhance the risk assessment of those departure countries. Thailand is considerably dependent on tourism, vulnerable to the negative socio-economic effects of the pandemic. It is crucial to mitigate the effect by prospectively evaluating control measures with additional consideration of international cooperation, economic evaluation, acceptance and satisfaction of travelers, local community, and domestic health system. Adopting data-driven approaches using open access databases to inform public health policy can aid in ensuring integrity, transparency, and adaptability in public health policy decision-making. Implication of thesis: The model can further be used to gain insights into Thailand’s re-opening of its international border or as a tool in preparing for outbreaks and disease control in the future. The results from the modelling will be presented as the number of case importations expected given the re-opening of Thai borders under different intervention strategies.