NUMBER OF CHILDREN WITHOUT 13-VALENT PNEUMOCOCCAL CONJUGATE VACCINE (PCV13) SERIES COMPLETION AT 2 YEARS OF AGE IN CANADA
Despite more than 6 years of routine pediatric PCV13 implementation in Canada, PCV13 serotypes still contributed to roughly 25% of invasive pneumococcal disease in older adults in 2017. One of the elements that can affect disease transmission and immunization program effectiveness is vaccine schedule completion. With transition to PCV13 in 2010/2011, a reduced, 2+1 routine immunization schedule was adopted across Canadian provinces, with the third dose recommended at 12 months of age.
We estimated the cumulative number of children with incomplete routine PCV13 vaccination series from 2011 to 2017, measured at 2 years of age. National Immunization Survey Coverage rates (available for 2011, 2013, 2015 and 2017; averaged for 2012, 2014 and 2016) along with Canadian census data were used to derive the number of children with incomplete PCV13 series.
There were ~609,000 children with incomplete PCV13 series at 2 years of age in Canada in 2011-2017 (Table 1).
The substantial estimated number of children with incomplete PCV13 series by 2 years of age over the study period, coupled with reduced-dose schedule may have undermined achievement of optimal public health impact. Potential role of these factors in PCV13 program effectiveness in Canada requires better understanding.