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.