Background: It is often assumed that there is correlation of Streptococcus pneumoniae (Sp) serotype distribution between invasive (INV) and non-invasive (N-INV) disease. This retrospective analysis assessed the correlations of the 13-Valent Pneumococcal Conjugate Vaccine serotypes (PCV13-type) between INV and N-INV diseases in US adults during 2009-2016.
Methods: For INV and N-INV pneumonia, we used a bank of Sp isolates from the SENTRY Antimicrobial Surveillance Program, where 105 centers across 40 states and nine U.S. Census regions collected isolates from sterile or non-sterile respiratory specimen types from consecutive patients with pneumonia (one per patient). The official online U.S. Active Bacterial Core (ABC) surveillance database for Sp was used for INV pneumococcal disease (IPD); ABCs conducts active surveillance in selected counties across 10 states in U.S.
Results: Of 6508 Sp isolates obtained from adults from the SENTRY database, 15% were from invasive pneumonia (mainly blood cultures). In 2009, PCV13 serotypes accounted for 55% and 37% of INV and N-INV pneumococcal pneumonia; in 2016, they accounted for 25% and 23%, respectively. Between 2009 and 2016, ABC reported 23,704 IPD cases in adults ≥18 years; PCV13 serotypes accounted for 53% in 2009 and 25% of IPD in 2016. The correlations between IPD (ABC) with INV pneumonia (SENTRY) and N-INV pneumonia (SENTRY) were: 0.937 and 0.973 (both p<0.01), respectively. (Table 1) The proportion of IPD and N-INV pneumonia due to vaccine serotypes decreased consistently and monotonically until 2014 and then plateaued. (Figure 1)
Conclusion: We found a strong correlation between databases (SENTRY and ABC) and between INV and N-INV pneumococcal disease in the proportion of disease due to PCV13-types. Our findings would need to be confirmed at the individual serotype level. The observed decrease in PCV13-type disease through 2014 is compatible with herd effect from PCV13 vaccination in children. The plateau suggests remaining disease that may be addressed by direct vaccination of adults. Surveillance of IPD alone could guide some policy on PCV13-type pneumococcal pneumonia.
J. A. Suaya,
R. E. Mendes, Merck: Research Contractor , Research support .
J. Vojicic, Pfizer: Employee and Shareholder , Benefits and stock and Salary .
D. L. Swerdlow, Pfizer Inc: Employee and Shareholder , Salary .
R. E. Isturiz, Pfizer, Inc: Employee and Shareholder , Salary and Stock & Stock Options .
B. D. Gessner, Pfizer Inc.: Employee and Shareholder , Salary .