Have changing pneumococcal vaccination programmes impacted disease in Ontario?

Publicly funded infant 7-valent pneumococcal conjugate vaccine (PCV7) was introduced in Ontario, Canada in 2005 and was replaced by 10- and 13-valent vaccines (PCV10, PCV13) in October 2009 and November 2010, respectively. Among adults ≥ 65 years, a 23-valent polysaccharide vaccine (PPV23) has been universally available since 1996. In January 2012, PCV13 was approved for adults ≥ 50 years. This study examines the impact of publicly funded vaccination programmes on invasive pneumococcal disease (IPD).Laboratory data from population-based surveillance for IPD conducted at the Toronto Invasive Bacterial Disease Network and from Public Health Ontario Laboratories between January 1, 2008 and December 31, 2010 were analyzed.Between 2008 and 2010 there were 3259 cases of IPD; overall incidence was 7.4/9.3/8.3 per 100,000 in 2008/9/10, respectively. Incidence increased significantly among adults 65+ years during the period; this group had the highest incidence (21.5-25.6/100,000). The second highest incidence in 2008 and 2009 was in infants1 year, whereas in 2010 it was in children 1-4 years. Among children5 years, 68% and 19% of serotypes were covered by PCV13 and PCV10, respectively, between 2008 and 2010. In 2009, 6 cases with the 3 additional PCV10 serotypes were reported in infants compared with 2 in 2010. Among persons eligible for PCV7 (born≥2004), there was a 77% decrease in the rate of IPD due to PCV7 serotypes between 2008 and 2010 and a 60% decrease in PCV7 serotypes among persons not vaccine-eligible (born2004). There was a 15% difference in serotype coverage between PCV13 and the 23-valent polysaccharide vaccine in adults≥50 years.During Ontario's PCV7 programme, serotype-specific decreases in IPD were observed, suggesting vaccine programme success, including herd immunity. Our results also suggest some early impact among infants from PCV10 introduction. A substantial burden of disease was also observed among older adults.