arXiv subjects

Yuna Lim

Publications and source records attributed to Yuna Lim.

3 recordsLinked to original sources

arXiv2026

Evaluating Targeted Mobility Restrictions on COVID-19 Transmission in Seoul: A Metapopulation Modeling Study Using Mobile Phone Data

Broad mobility restrictions can help control infectious disease spread, but their socioeconomic costs and the variation in transmission risks by mobility purpose, age group, and spatial connectivity highlight the need for targeted approaches. In this study, we developed an age-structured SEIR metapopulation model for COVID-19 across Seoul's 25 districts, integrating mobile phone-derived origin-destination data. We stratified mobility by age (0-19, 20-59, 60+) and purpose: residential (H), school/work (W), and other non-routine (O). Using 2024 mobility data as a baseline and incorporating pandemic-period (2020-2021) mobility deviations, we investigated counterfactual strategies under various targeting scenarios. Our results showed that W restrictions among adults aged 20-59 produced the highest per-capita reductions in infection. Spatial clustering based on population-adjusted W inflows showed that high-inflow central business districts corresponded to the fast-spreading districts identified in the simulations. Targeting W flows into and within this cluster consistently reduced epidemic size across uncertain seeding locations. Furthermore, weekday-inclusive schedules outperformed weekend-only restrictions. Overall, our findings suggest that although citywide restrictions achieve larger reductions, strategically targeting routine school/work mobility among adults aged 20-59 within fast-spreading clusters can provide substantial epidemiological benefits while reducing broader socioeconomic disruption.

q-bio.PE↗

arXiv2026

Cost-Effectiveness of Adult Hepatitis A Vaccination Strategies in Korea Under an Aging Susceptibility Profile

Hepatitis A severity increases sharply with age, while Korea is experiencing a cohort shift in which low seroprevalence adult cohorts are aging into older, higher fatality age groups. This demographic and immunological transition creates an urgent policy question regarding how adult vaccination should be prioritized under resource constraints. We evaluated three adult vaccination scenarios targeting low seroprevalence age groups (S1) 20 to 39 years, (S2) 40 to 59 years, and (S3) 20 to 59 years. Using an age structured dynamic transmission model calibrated to Korean data, we derived dynamically feasible vaccination allocation trajectories under realistic capacity constraints using an optimal control framework and linked these trajectories to long term transmission model simulations. We conducted DALY based cost effectiveness analyses over a lifetime horizon from both healthcare system and societal perspectives, and characterized uncertainty using probabilistic sensitivity analysis (PSA) and cost effectiveness acceptability curves (CEACs). Robustness was examined using one way sensitivity analyses. In the base case, S2 consistently yields the most favorable and robust cost effectiveness profile under both perspectives, with the lowest ICER. S3 achieved the largest reduction in DALYs but requires substantially higher incremental costs, resulting in a higher ICER than S2. S1 produces the smallest DALY reduction and is the least efficient strategy. PSA and CEACs confirm that S2 remains the preferred option across most willingness to pay ranges. S2 offers the most balanced and robustly cost effective strategy in Korea, capturing substantial mortality reduction while limiting additional program costs. S3 may be justified when higher budgets or willingness to pay thresholds are acceptable, but S2 provides the clearest value for money under epidemiological and economic conditions.

q-bio.PE↗

arXiv2025

Comparison of the effectiveness and costs of hepatitis A vaccination strategies to mitigate future deaths in the Republic of Korea

Improved hygiene and infant vaccinations have led to age specific variations in hepatitis A antibody prevalence in Korea, with lower rates among individuals in their 20s to 40s. Given that the fatality rate of hepatitis A increases for those aged 50 and older, the low immunity level among younger adults indicates a future risk of increased deaths in older age groups without additional preventive measures.We developed an age structured transmission model to assess the impact of adult vaccination, assuming it begins in 2025. The 20s age group was modeled with an additional compartment to account for hepatitis A vaccination administered to military recruits. Vaccination strategies targeting the 20s to 30s and 40s to 50s age groups were compared, considering antibody testing costs for the latter in Korea and focusing on projected deaths over approximately 50 years. When the total vaccination cost is fixed, targeting the 40s to 50s group covers 20% fewer individuals than the 20s to 30s group but yields a 1.3 to 1.5 fold greater reduction in deaths. When the total vaccine supply is fixed, targeting the 40s to 50s group is 1.2 times more expensive but yields a 1.7 to 1.8 fold greater reduction in deaths than the 20s to 30s group. Moreover, including a second dose for military personnel in the 20s to 30s group has minimal impact on reducing deaths. Preventive measures for adults may be necessary to reduce future hepatitis A related deaths. Vaccinating the 40s to 50s group would be more effective in reducing deaths than vaccinating the 20s to 30s group.

q-bio.PE↗