Invasive Pneumococcal Disease (IPD) in Children and Adults Following Introduction of Pneumococcal Conjugate Vaccines: Data From Population Based Surveillance 2001–2015

Abstract

Background. In Ontario, PCV7 was publicly funded in Januar 2005 (3 + 1 schedule), PCV10 in October 2009 and PCV13 in November 2010 (2 + 1 schedule with catchup for up to 35 months old). TIBDN performs population-based surveillance for invasive pneumococcal disease (IPD) in Toronto/Peel to evaluate program impact. Methods. IPD cases are reported to a central office and 1 isolate/case is serotyped (ST). Demographic and clinical data are collected by chart review and patient/physician interview. Results. From 2001 to 2015, 6594 IPD cases were identified and ST was available for 6046 (92%). Sixteen percent of cases were aged <15 years). 28% required ICU admission. Presenting diagnosis were pneumonia (68%), bacteremia without focus (17%) and meningitis (7%). The IPD rate decreased from 8 to 7/100,000/year (2005/2010 versus 2013/2015) in adults and from 11 to 5/100,000/year in (2009 versus 2013/2015) in children. Since the introduction of PCVs, non-PCV ST IPD has increased from 2.6 to 4/ 100,000/year in adults and from 1.3 to 3.5/100,000/year in children (2001/4 versus 2013/5). IPD due to ST23A has increased in adults from 0.1 to 0.2 in 2001/2004 to 0.3 to 0.4/100,000/year in 2013/2015; and from no cases in children in 2001/2007 to 0.2-0.6/100,000/year in 2013/2015. In 2014/2015, STs were available for 88% of cases; STs 22F (12%), 19A (10%), 3 (9%), and 23A (7%) were the most common in adults. STs 19A (22%), 22F (10%), 3 (10%), 15B (8%), and 15C (8%) were the most common in children. Non-PCV STs represented 70% of cases in 2015. From 2013 to March 2016, 165 pediatric IPD cases were identified. ST was available for 143 (87%). Forty-five were due to PCV13/non7 STs. Seven were ineligible for PCV13 (aged >35 months when catch-up program was implemented or <2 months of age or immigrated to Ontario at age >35 months). Vaccine history was available for 34 PCV13 vaccine-eligible children with PCV13/ non7 ST disease (10 in 2013, 14 in 2014, 7 in 2015, and 3 in January-March 2016). Six were unvaccinated (4 ST19A, 2 ST3), 11 missed ≥1 scheduled doses (8 ST19A, 2 ST3, 1 ST7F); 7 were eligible for a single dose only (2 ST19A, 5 ST3); 1 (ST3) was a child (11 months) who received doses at 2 and 4 mos; and 9 were vaccine failures (6 ST19A, 2 ST3, 1 ST5). Conclusion. Since PCV13-program implementation, the IPD rate due to PCV13/ not7 STs has decreased in children and adults. NonPCV ST IPD has increased and in 2015 represented 70% of cases. (Figure Presented) .