1426. Impact of Routine Pediatric PCV13 on the Incidence and Severity of Invasive Pneumococcal Disease in Adults in Ontario, Canada

BACKGROUND: Monitoring the incidence and severity of disease due to varied pneumococcal (Pn) serotypes (STs) over time is important in assessing the benefit of Pn vaccines. We describe changes in adult IPD after the 2010 introduction of routine infant PCV13 in Ontario, Canada (PCV13 is funded only for immunocompromised adults ≥50 years as of 2015). METHODS: TIBDN has conducted population-based surveillance for IPD in Toronto/Peel, Canada (pop 4.3M) since 1995. Cases are reported to a central office; one isolate/case is serotyped. Demographic and clinical data are collected by chart review and patient/family physician interview. RESULTS: Of 6,275 episodes of adult IPD, 5,674 (90%) have STs and 6,007 (96%) detailed clinical data. Incidence of IPD decreased from 14.2/100,000/year in 1995 to 6.0/100,000/year in 2013–2017). One thousand two hundred and three (19%) adults with IPD were 15–44 years, 1,889 (30%) were 45–64 years, 3,182 (51%) ≥65 years. Figures 1 and 2 show rates over time by ST group and age. In multivariable analyses, there was no difference across vaccine ST groups (nonvaccine type (NVT) vs. PPV23 not PCV vs. PCV13) in patient age, proportion with ICU admission, requirement for mechanical ventilation (MV), death, length of stay (LOS) or diagnosis of meningitis, except that patients with NVT isolates were more likely to require ICU admission (OR 1.5, 95% CI 1.2,2.0), and to have meningitis (OR 1.9, 95% CI 1.1,3.3). Case fatality declined from 25% (480/1,949) 1995–2001 to 19% (148/763) in 2012–2017 (multivariable OR/year 0.98 95% CI 0.97,0.99); requirements for ICU admission (26–31%; OR/year 1.02, 95% CI 1.01,1.03) and MV (OR/year 18–22%; 1.02, 95% CI 1.01–1.03) increased, LOS did not change. From 2013 to 2017, the distribution of vaccine group STs has not changed: 37% PCV13 (383/1,031); 20% PCV20not13 (205); 9% PPV23not 20 (94), 34% NVT (349). NVT strains include over 23 ST, most commonly 23A (72, 21%), 15A (46, 13%), 35B (37,11%), 6C (36, 10%), 23B (20, 8%). CONCLUSION: In our population, with infant but no routine adult PCV13, the incidence of adult IPD appears to have stabilized, with PCV13 ST strains contributing 37% of IPD. Case fatality has decreased; ICU admission increased. Adult vaccination may be required to further reduce PCV13 ST infections. Figure 1: IPD incidence, adults 15–65 years, by ST group, 2006–2017. Infant PCV7 started 2005 and PCV13 in 2010. [Image: see text] DISCLOSURES: A. McGeer, Pfizer: Grant Investigator and Scientific Advisor, Research grant and Research support; Merck: Scientific Advisor, Research support; GlaxoSmithKline: Grant Investigator and Scientific Advisor, Research support.