An Analysis of Circulating Invasive Pneumococcal Disease Serotypes in South Africa and the Potential of New and Existing Pneumococcal Vaccines to Prevent Disease and Death, 2012–2021

Abstract

In recent years, various new pneumococcal conjugate vaccines (PCVs) (PCV10-SII, PCV15 and PCV20) containing different serotypes entered the global market to prevent invasive pneumococcal disease (IPD). This study aimed to assess the potential of these vaccines in preventing IPD within different populations in South Africa (SA) compared to current vaccines in use (PCV13 and the 23-valent pneumococcal polysaccharide vaccine (PPSV23)). A retrospective, descriptive, secondary analysis of primary data collected by GERMS-SA between 2012-2021 was performed. IPD incidence, serotype distribution and proportions of serotypes within pneumococcal vaccines were calculated. The association between case fatality rates and IPD serotypes, age group, province, HIV status, multidrug resistance and comorbidities were calculated through logistic regression. Between 2012 and 2021, 23 789 episodes of IPD were reported to GERMS-SA across South Africa. IPD incidence followed a decreasing trend, with an average annual incidence rate of 4.22 cases per 100 000 persons. was Absolute numbers of IPD cases were highest in persons between the ages of 25-44 years old. Common serotypes noted to cause IPD across the population were serotypes 8 (11%), 19A (8%) and 12F (8%). Across the vaccines assessed, PPSV23 (68%) contained the highest percentage of serotypes causing IPD in SA, followed by PCV20 (63%), PCV15 (40%), PCV13 (37%) and lastly, PCV10-SII (26%). PCV10-SII contained the highest proportion (> 50%) of serotypes causing penicillin and ceftriaxone antimicrobial resistance in IPD cases compared to the other vaccines. The case fatality rate across IPD cases between 2012-2021 was 32%. Children less than one years old (aOR:1.074 ; 95% CI (1.015-1.137)), adults aged 45-65 years old (aOR: 1.155; 95% CI (1.095-1.219)) and those older than 65 years (aOR: 1.208; 95% CI (1.120-1.304)), as well as people living with HIV (aOR: 1.044; 95% CI (1.013-1.076)) were all noted to have a significantly higher odds of death. Interestingly, no other comorbidities were significantly associated with higher odds of mortality when controlling for age, province, the presence of other comorbidities and risk factors. Next-generation higher-valent PCVs contain a moderate to high proportion of IPD serotypes circulating in SA and vulnerable populations including the extremes of ages, persons with comorbidities and the immunocompromised should be continuously targeted. These findings convey important implications for future pneumococcal vaccine use and policy in SA.