Effectiveness of pneumococcal conjugate 13-valent vaccine against severe pneumonia in Panama: a matched case-control study.

Objective: In Panama, the 13-valent pneumococcal conjugate vaccine (PCV13) was included in the primary immunization schedule in 2010 with a 3-dose schedule. The authors evaluated the effectiveness of PCV13 against severe community-acquired pneumonia in children of Panama after its introduction into the national immunization program.

Methods: A retrospective matched case-control study was conducted at Hospital del Niño Doctor José Renán Esquivel, collecting data from children 2 to 59 months of age in years subsequent to the introduction of the PCV13 vaccine (2013-2015). Cases of severe community-acquired pneumonia had radiographically confirmed pneumonia (consolidated or with pleural effusion) or pneumonia with "other infiltrate" associated with CRP ≥ 40 mg/L with severity criteria according to the 2013 World Health Organization definition. Controls were children hospitalized for non-immune-preventable diseases matched by cases' age and admission date. Vaccine effectiveness was estimated as (1 - odds ratio) × 100 % with 95 % confidence intervals.

Results: 78 paired cases with 198 controls were included. In the cases, the mean age was 13.7 ± 10.3 SD months, and the hospital stay was 9.7 + 6.1 days. Overall, the effectiveness of PCV13 against severe community-acquired pneumonia was 54.0 % (95 % CI 25.0-72.0 %, p < 0.05). Vaccine effectiveness among children under 1 year was 61 % (95 % CI: 23.0-81.0 %) and 43 % (95 % CI:16.0-74.0 %) for children 1 to 4 years. For children who received at least 1 PCV13 dose was 17.2 % (95 % CI: 8.8-33.7 %). Overcrowding and lack of vaccination against influenza were risk factors for lower vaccine effectiveness.

Conclusions: PCV13 was effective in preventing severe cases of community-acquired pneumonia in children in Panama.