Early Impact of 13-Valent Pneumococcal Conjugate Vaccine Use on Invasive Pneumococcal Disease Among Adults With and Without Underlying Medical Conditions-United States.

Background: The 13-valent pneumococcal vaccine (PCV13) was introduced for US children in 2010 and for immunocompromised adults ≥19 years old in series with the 23-valent polysaccharide vaccine (PPSV23) in 2012. We evaluated PCV13 indirect effects on invasive pneumococcal disease (IPD) among adults with and without PCV13 indications.

Methods: Using Active Bacterial Core surveillance and the National Health Survey, using Active Bacterial Core surveillance and the National Health Interview Survey, we estimated and compared IPD incidence in 2013-2014 and 2007-2008, by age and serotype group (PCV13, PPSV23-unique, or nonvaccine types [NVTs]), among adults with and without PCV13 indications.

Results: IPD incidence declined among all adults. Among adults 19-64 years, PCV13-type IPD declined 57% (95% confidence interval [CI], -68% to -43%) in adults with immunocompromising conditions (indication for PCV13 use), 57% (95% CI, -62% to -52%) in immunocompetent adults with chronic medical conditions (CMCs, indications for PPSV23 use alone), and 74% (95% CI, -78% to -70%) in adults with neither vaccine indication. Among adults aged ≥65 years, PCV13-type IPD decreased 68% (95% CI, -76% to -60%) in those with immunocompromising conditions, 68% (95% CI, -72% to -63%) in those with CMCs, and 71% (95% CI, -77% to -64%) in healthy adults. PPSV23-unique types increased in adults 19‒64 years with CMCs, and NVTs did not change among adults with or without PCV13 indications. From 2013 to 2014, non-PCV13 serotypes accounted for 80% of IPD.

Conclusions: IPD incidence among US adults declined after PCV13 introduction in children. Similar reductions in PCV13-type IPD in those with and without PCV13 indications suggest that observed benefits are largely due to indirect effects from pediatric PCV13 use rather than direct use among adults.