Globally, pneumococcal diseases are a common cause of morbidity and mortality. However, the rates of disease prevalence and mortality are higher in developing countries as compared to developed countries, with the majority of deaths being reported from Asia and sub-Saharan Africa. The incidence of pneumococcal diseases is most common at the extremes of age, that is, among children and the elderly population.¹ Globally, S. pneumoniae is the leading cause of pneumonia-related mortality. In 2016, S. pneumoniae accounted for more deaths than all other causes (aetiologies) combined; most of such deaths occurred in Africa and Asia.²

Data from the CDC revealed 17 cases of IPD per 100,000 people in the United States, across all age groups. The incidence rate of 7 persons per 100,000 individuals across all age groups has been reported in England and Wales, with a higher rate of 21 persons per 100,000 in individuals aged ≥65 years. For IPD in adults, the CFR may reach 15% to 20% and even up to 30% to 40% in the elderly population.³ In North America, the incidence rates of IPD varied between 15 and 49 persons per 100,000, while in Europe, the incidence ranged from 11 to 27 persons per 100,000 individuals. In the United States, more than 36,000 cases of IPD were reported in 2011. The incidence of IPD was strikingly age related; 54% of cases were reported in adults >50 years of age and 38% of cases were reported in children below 2 years. Much higher incidence rates of IPD have been reported from Asia; in Taiwan, up to 216 cases per 100,000 were reported annually.⁴ The incidence rates of CAP reported in different countries of Europe are: 1.6 per 1000 in Spain, 11.6 per 1000 in Finland and 3.7 to 10.1 per 1000 in Germany. The overall incidence of CAP sharply increases with age. While the estimated incidence rate of CAP was 18.2 per 1000 person-years in the 65- to 69-year age group, it increased to 52.3 per 1000 person-years in individuals aged >85 years. In Germany, while the overall CAP incidence was 2.9 per 1000, it increased up to 7.7 in adults aged >60 years and 35.8 in adults aged >90 years.⁴

Moreover, the hospitalisation rate among patients with pneumonia also increases with age. Between the periods 1988 to 1990 and 2000 to 2002, a 20% increase in the hospitalisation rates among the elderly patients was observed in the United States. Furthermore, the mortality rates were also significantly higher in the elderly patients with CAP as compared to the patients aged below 65 years; the rates being 10.3% and 2.2%, respectively, in a Spanish cohort. In elderly patients with CAP who require mechanical ventilation, as high as 55% mortality rates have been observed.⁴ In a surveillance study in 4 European countries, increase in the incidence, likelihood of hospitalisation and fatality rates were reported with increasing age. As compared to adults aged 50 to 64 years, the hospitalisation rate was 2.3-fold higher in adults aged 65 to 74 years, 5.2-fold higher in adults aged 75 to 84 years and 10.8-fold higher in older adults aged ≥85 years.⁵ 

A Swiss study identified both the age groups, ≥65 years (vs. <65 years) (OR, 4.14; 95% CI, 4.11-4.17) and ≥50 years (vs. <50 years) (OR, 4.98; 95% CI, 4.93-5.03), as significant risk factors for hospitalisation with pneumonia, as compared to hospitalisations without pneumonia diagnosis.⁶ Therefore, it is important to focus on preventive measures against pneumococcal diseases in the elderly group of patients with high vulnerability.⁴

The PCV, PCV13, was introduced in 2012 for use in adult population. As per the surveillance report of the CDC, in the United States, the overall IPD cases in adults aged ≥65 years decreased from 59 persons per 100,000 in individuals in 1998 to 23 persons per 100,000 in individuals in 2015. IPD in adults aged ≥65 years caused by the serotypes covered in PCV13 decreased from 44 cases per 100,000 in 1998 to 5 cases per 100,000 in 2015. In this group of elderly patients, IPD cases caused by serotypes covered in PPSV23 declined from 53 cases per 100,000 in 1998 to 15 cases per 100,000 in 2016. However, these reductions in the IPD cases caused by PPSV23 serotypes were caused by the serotypes in common with PCV13.⁷

Adapted from CDC. Surveillance and reporting. 2020.
 

In case of persons with comorbidities, pneumococcal diseases occur more frequently as compared to healthy persons and are comparatively more deadly. The incidence rates are found to be higher with advancing age in adults and in those adults with comorbidities such as solid cancer, diabetes and chronic lung diseases. Therefore, better prevention strategies are required for such at-risk groups of adults.⁸

The incidence of pneumococcal disease increases with comorbidities such as diabetes, COPD, malignancies, etc.⁸

Adapted from Kyaw MH, et al. 2005.
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