Table 2.

Description of Case-Control Studies of 13-Valent Pneumococcal Conjugate Vaccine (PCV13) in Children Who Have Reported Data on PCV13 Effectiveness on Serotype 3 Invasive Pneumococcal Disease

Study, Location	Design	Setting/Data Source	Study Period	PCV Use in Infant NIP	Definition/Identification of Cases	Definition/Identification of Controls	Adjustment or Matching of Cases and Controls	Ascertainment of Vaccination Status	Children Immunized With Lower Valent Vaccines Included in VE Analyses for Serotype 3
Published studies
Study 1, United States [6]	Matched case-control	Population-based IPD surveillance system: ABCs	Jan 2010 to Dec 2014	PCV7: 2000, 3 + 1 PCV13: 2010, 3 + 1	Children with IPD and resident of ABC site	4 controls per case identified via state birth certificate registry	Controls matched for age and location	Medical record	No
Study 2, Spain [13]	Matched case-control	3 pediatric hospitals in Barcelona	Jan 2012 to June 2016	See footnotea	Children hospitalized with IPD	4 controls per case; patients admitted to same hospital as cases for cause other than IPD	Controls matched for age, sex, date of hospitalization, and underlying medical condition	Medical record	No
Study 3, Germany [14]	Indirect cohort	Voluntary national IPD surveillance system: German National Reference Center for Streptococci	July 2006 to June 2015	PCV7: 2006, 3 + 1 PCV13: 2009, 3 + 1b	Children with IPD reported to National Reference center. Cases = vaccine type IPD	Children with IPD reported to National Reference center. Controls = nonvaccine-type IPD	VE adjusted for age and time period	Questionnaire (diagnostic laboratory)	No
Study 4, United Kingdom [15]	Indirect cohort	National IPD surveillance system: PHE	Apr 2010 to Oct 2013	PCV7: 2006, 2 + 1 PCV13: 2010, 2 + 1	Children with IPD identified by national IPD surveillance system. Cases = vaccine type IPD	Children with IPD identified by national IPD surveillance system. Controls = nonvaccine-type IPD	VE adjusted for age and time period	Questionnaire (general practitioner)	Yes, PCV7
Conference posters
Study 5, European Union [24]	Indirect cohort	Streptococcus pneumoniae invasive disease network	Jan 2012 to Dec 2014	PCV7: 2009–2011, 2 + 1 or 3 + 1; PCV13: 2009–2010 2 + 1 or 3 + 1	Children with IPD identified by active surveillance system. Cases = vaccine type IPD	Children with IPD identified by active surveillance system. Controls = nonvaccine-type IPD	VE adjusted for site, age, sex, underlying conditions, and year of notification	Not reported	Not reported
Study 6, Canada [25]	Unmatched case-controlc	Children residing in province of Quebec	2005–2016	PCV7: 2002, 2 + 1 or 3 + 1; PCV10: 2009, 2 + 1; PCV13: 2011, 2 + 1	Children with IPD notified to regional public health authority	Children randomly selected in the Quebec Health Insurance Registry	VE adjusted for age, season, calendar year, and presence of high-risk medical conditions	Medical record	PCV7- or PCV10-immunized children considered “not vaccinated”

Abbreviations: ABCs, active bacterial core surveillance; IPD, invasive pneumococcal disease; NIP, National Immunization Program; PCV, pneumococcal conjugate vaccine; PCV7, 7-valent pneumococcal conjugate vaccine; PCV10, 10-valent pneumococcal conjugate vaccine; PCV13, 13-valent pneumococcal conjugate vaccine; PHE, Public Health England; VE, vaccine effectiveness.

^aThe Vaccination Advisory Committee of the Spanish Association of Pediatrics has recommended the routine administration of conjugate pneumococcal vaccines (PCV7 since 2003 to 2010 and, currently, PCV13, 2 + 1). These vaccines were not financed by the Catalan Public Health System until July 2016, except in children with selected risk factors, and were only available in the private sector. In Spain, the vaccine was not introduced into the recommended schedule until January 2017, and there are no estimates of vaccination coverage [13].

^bPCV13 schedule changed to 2 + 1 in August 2015 except for preterm infants.

^cControls were stratifed by age (2–5 months; 6–11 months; and 1, 2, 3, or 4 years of age).