Dear Sir(s),
With reference to the recent publication from Van Hoek and Miller (Cost-Effectiveness of Vaccinating Immunocompetent >65 Year Olds with the 13-Valent Pneumococcal Conjugate Vaccine in England, PlosOne, February 25th, 2016) we would like to bring to your attention different outcomes on mortality that we preliminarily observed in Italy.
Previous studies have analyzed the factors associated with mortality in patients hospitalized for CAP, demonstrating the direct association between pathogen types, subject characteristics (age, sex and comorbidities) and relevant mortality. Nevertheless, vaccination status against pneumococcal disease has not been considered yet due to lack of data. In order to preliminarily assess the impact of vaccination against pneumococcal disease in the elderly, including the recommended use of pneumococcal 13-valent conjugate vaccine (PCV13), we analyzed mortality rates following first hospitalization for Community Acquired Pneumonia (CAP) in North Est Italy. A retrospective study was started in 2015 and is currently in the final phase. We included patients aged over 64 years hospitalized for CAP in the 2012–2013 period. The cohort was followed for 1 year after the subjects were discharged. Outcomes of interest are pneumonia and COPD mortality. Based on the pre-hospitalization vaccination status for pneumococcal disease, the whole cohort was divided into three groups: 1) not vaccinated, 2) vaccinated with the 23-valent pneumococcal polysaccharide vaccine (PPSV23) and 3) vaccinated with PCV13. Subject clinical background and death causes were evaluated through the Regional electronic integrated system of health data and coded accordingly.
Briefly, 4,030 patients were hospitalized with a primary diagnosis of pneumonia; patients were female 50.9% and overall mean age at hospitalization was 84.3±7.7; 70.2% of subjects were aged about 80 years. Of the subjects, 74.2% showed at least one chronic comorbidity and 68.9% was vaccinated against influenza. With reference to the pneumococcal vaccine status, 80.4% of patients was unvaccinated, 14.5% was vaccinated with PPSV 23 and 5.1% was vaccinated with PCV13.
Over the study period, the overall case fatality rate was high (56.8%) without significant differences among all three study group. However, the preliminary analysis showed that PCV13 vaccination plays an important role in reducing pneumonia and COPD mortality in elderly subjects. In fact, pneumonia and COPD mortality rate (merged as a unique respiratory category) showed a significant decrease of approximately 7% compared to unvaccinated subjects (OR: 0.57 95% CI: 0.37-0.89; p=0.01) and approximately 5% compared to PPSV23 vaccinated subjects (OR: 0.65 95% CI: 0.40-1.05; p=0.07) over the follow-up period.
We think that these preliminary results should be taken into consideration and discussed. Accordingly, long-term studies to confirm the PCV13 benefits currently highlighted in terms of fatality rates related to respiratory cause of death will be needed.

Vincenzo Baldo, Silvia Cocchio
University of Padua, Italy