OBJECTIVES: This study aimed to assess clinical impact of replacing PCV13 with PCV15 in the national immunization program (NIP) for infants in Costa Rica.

METHODS: A state-transition Markov model was utilized to simulate the occurrence of cases and deaths associated with pneumococcal disease (PD) in Costa Rica population. The model incorporated three health states: no PD, post-meningitis sequelae (PMS), and death; and tracked the occurrence of acute PD events, including acute otitis media (AOM), non-bacteremic pneumococcal pneumonia (NBPP), and invasive pneumococcal disease (IPD). Health outcomes, including life-years (LYs), were reported. The initial birth cohort in 2024, consisting of 69,654 newborns, and the subsequent 100 cohorts were eligible to receive either PCV13 or PCV15 according to the 2+1 schedule, administered at 2, 4, and 12 months. Costa Rican-specific data from official sources/literature were used, with data from other Latin America countries as proxy, when necessary. A life table was included to account for all-cause mortality among the cohorts. The same vaccine-type efficacy and waning profile was assumed for both vaccines. For the two additional PCV15 serotypes (22F and 33F), the average overall PCV13 vaccine efficacy was applied, including indirect effect for the first five years following PCV15 introduction.

RESULTS: Replacing PCV13 with PCV15 in the Costa Rican NIP was projected to avoid additional 740 IPD cases (53 meningitis, 158 bacteremia without focus, and 528 bacteremic pneumonia), 4,260 NBPP cases (1,865 inpatient and 2,395 outpatient NBPP), 3,297 AOM cases and 16 PMS cases over a 100-year time horizon. Additionally, PCV15 was estimated to avoid 84 IPD/NBPP deaths compared to PCV13, resulting in gains of 1,606 LYs over the 100-year time horizon.

CONCLUSIONS: PCV15 is projected to prevent more PD-related cases and deaths compared with PCV13. These findings highlight the additional impact of PCV15 in preventing PD mortality and morbidity in Costa Rica.