Evolution of pneumococcal serotypes, vaccination uptake, and prognosis of invasive pneumococcal disease: A 9-year multicentre cohort study in Granada (Andalusia, Spain).

OBJECTIVE

Our aim was to analyse the serotypes, vaccination and risk factors associated with in-hospital mortality in patients diagnosed with invasive pneumococcal disease (IPD) in two hospitals in Spain.

METHODS

A retrospective cohort study (2015-2024). Inclusion criteria were adults with IPD and with a serotyped sample registered in our microbiology services. Data were obtained through electronic medical records. The main exposure was pneumococcal vaccination, and the main outcome was in-hospital mortality. Bivariate, multivariable, and survival analyses were performed using R.

RESULTS

A total of 188 patients with IPD were included. The most frequent serotypes were 8, 3, 22F, 9 N and 11A. No previous pneumococcal vaccination was shown in 106 (58.6 %) patients. More than 30 % of serotypes were not included in the pneumococcal vaccines currently used in Spain. In-hospital mortality occurred in 27 (14.4 %) patients. Cox regression models showed older age (HR = 1.05, 95 %CI: 1.02-1.08), living in long-term care facilities (HR: 3.27, 95 %CI: 1.36-7.82), septic shock at admission (HR = 2.71; 95 %CI: 1.30-5.67), intensive care admission (HR = 2.64; 95 %CI: 1.53-4.57) and no previous pneumococcal vaccination (HR = 2.14; 95 %CI: 1.86-2.47) as the main factors associated with higher in-hospital mortality due to IPD.

CONCLUSIONS

Low frequency of pneumococcal vaccination uptake in adult patients with IPD was demonstrated. Older age, living in long-term care facilities, dependency, septic shock at admission, and no previous pneumococcal vaccination were associated with higher in-hospital mortality. Immunization strategies should imperatively be optimised so as to reduce mortality from IPD.