The Risk of Invasive Pneumococcal Disease Differs between Risk Groups in Norway Following Widespread Use of the 13-Valent Pneumococcal Vaccine in Children

Abstract

The elderly and adults with medical risk conditions remain at high risk of invasive pneumococcal disease (IPD), highlighting the importance of adequate preventive efforts. In an observational population-based study in Norway (pop ≥ 5 years, 2009–2017) covering six years post-PCV13 implementation, we explored the incidence and risk of IPD associated with age and comorbidities. We obtained the data on 5535 IPD cases from the Norwegian Surveillance System for Communicable Diseases and the population data from Statistics Norway. To define comorbidities, we obtained ICD-10 codes from the Norwegian Patient Registry for the cases and the Norwegian population. The average annual decrease in PCV13 IPD incidence was significant in all risk groups and decreased post-PCV13 introduction by 16–20% per risk group, implying a nondifferential indirect protection from the childhood vaccination. The IPD incidence remained high in the medical risk groups. The relative importance of medical risk conditions was 2.8 to 6 times higher in those aged 5–64 versus ≥65 years for all types of IPD, since age itself is a risk factor for IPD. In groups without medical risk, the risk of IPD was eight times higher in those aged ≥65 compared to those 5–64 years (RR 8.3 (95% CI 7.3–9.5)). Our results underscore the need for age- and risk-group-based prevention strategies.

Estimation of the incidence of hospitalisation for non-invasive pneumococcal pneumonia in the Norwegian population aged 50 years and older

“…We identified that for each episode of invasive PnPn there are at least three episodes of non-invasive PnPn, which is in line with findings in other studies [5,6]. We found that the number of episodes was 8 times higher in the oldest age group (age 80+) compared to the youngest (age 50-59), indicating that the risk of hospitalisation due to non-invasive PnPn increases with age, just like IPD [8]. This corresponds to observations reported from other countries [3,16,20,21].…”

“…In agreement with these findings, a more recent study from the Netherlands (among 409 patients) found that 30% of the PnPn episodes were invasive and 70% non-invasive [6]. Both, young children, elderly and persons with weakened immune systems are at high risk of acquiring pneumococcal disease [7, 8].…”

“…The vaccine uptake in the study population (50+ ) has been low, around 15% [8]. A study conducted in Norway at the time of our study period reported that 16% of notified cases of IPD had received the PPV23 vaccine [24].…”

“…However, as of today, there is no national immunisation programme for pneumococcal vaccination for older adults (50+) in Norway, therefore costs are not reimbursed. Uptake has been low (around 15%) and differences related to social, economic and place of residence (geographical factors) may occur [8]. Because of the increasing proportion of 50+ population in Norway, likely resulting in an increasing demand for health care in the next few decades, preventing infectious diseases through immunisation will be essential [11].…”

Cost-utility analysis of a universal pneumococcal vaccination programme for older adults in Norway

“…In Norway, after 2016, a declining incidence of IPD caused by both PCV13 (13-valent pneumococcal conjugate vaccine) and non-PCV13 IPD was observed, though the proportion of non-PCV13 serotypes is increasing compared to PCV13 serotypes. 4 …”