Dynamics of Invasive Pneumococcal Disease in Israel in Children and Adults in the 13-Valent Pneumococcal Conjugate Vaccine (PCV13) Era: A Nationwide Prospective Surveillance.

BACKGROUND

Following 13-valent pneumococcal conjugate vaccine (PCV13) implementation in infants worldwide, overall and vaccine-type invasive pneumococcal disease (IPD) rates declined in children, with variable indirect impact on adults.

METHODS

A population-based, prospective, nationwide active surveillance of IPD in Israel, 2004-2019 (for adults ≥18 years, 2009-2019). The 7-valent PCV (PCV7)/PCV13 were implemented in Israel in July 2009/November 2010, respectively, with >90% uptake in children <2 years. The 23-valent pneumococcal polysaccharide vaccine (PPV-23) uptake among those >65 years was ~75%. For pre-PCV episodes with missing serotype, extrapolations were applied. Overall, PCV13 serotypes (VT13) and non-VT13 (NVT) incidence rate ratios (IRRs) comparing pre-PCV (2004-2008), early-PCV (2009-2011), and late-PCV13 (2016-2019) periods were calculated for different age groups.

RESULTS

Overall, 8614 IPD cases were recorded. IPD rates declined by 67% in children <5 and 5-17 years, comparing late-PCV13 versus pre-PCV periods (IRR [95% CI]: .33 [.27-.40] and .33 [.21-.50], respectively). For adults, comparing late-PCV13 with early-PCV periods, rates significantly declined by 53% in those aged 18-44, while rates did not decline significantly in other age groups. VT13 rates significantly declined in all ages, with decline rates ranging between 94% in children <5 years and 60% in adults ≥85 years. NVT rates significantly increased in <5-, 50-64-, and ≥65-year age groups. In the late-PCV13 period, serotypes 3, 14, and 19A remained the predominant VT13, while serotypes 8 and 12F emerged as predominant NVTs.

CONCLUSIONS

Continuous monitoring of circulating serotypes in all ages demonstrated direct and indirect PCV effects, which are essential for the development of new vaccination strategies.