Impact of pneumococcal vaccines use on invasive pneumococcal disease in Nunavik (Quebec) from 1997 to 2010.
BACKGROUND
In 2000, an outbreak of severe pneumonia caused by a virulent clone of serotype 1 Streptococcus pneumoniae was detected in the Nunavik region of Quebec. A mass immunization campaign was implemented in the spring of 2002, targeting persons ≥5 years of age and using the 23-valent pneumococcal polysaccharide vaccine (PPSV23). At the same time, the 7-valent pneumococcal conjugate vaccine (PCV7) was introduced into the routine immunization programme of infants, with catch-up for children up to 4 years of age.


OBJECTIVE
To describe the epidemiology of invasive pneumococcal disease (IPD) in relation to PPSV23 and PCV7 use.


METHODS
Retrospective analysis of IPD cases identified by the Quebec public health laboratory during the period 1997-2010.


RESULTS
A total of 82 IPD cases were identified during the study period. In adults, serotype 1 incidence decreased following the 2002 PPSV23 mass campaign but breakthrough cases continued to occur. Following PCV7 use in children, there was a decrease in the incidence of vaccine-type IPD and replacement by other serotypes in adults. In children, a marked decrease in the annual incidence of serotypes included in PCV7 was observed following PCV7 introduction: 162/100,000 in 1997-2001 vs. 10/100,000 in 2004-2010 (p<0.01). Concomitantly, the incidence of IPD caused by serotypes not included in PCV7 increased from 29/100,000 to 109/100,000 (p=0.11).


CONCLUSIONS
The mass immunization campaign using the PPSV23 in 2002 and the introduction of PCV7 for the routine immunization of infants induced important modifications in the epidemiology of IPD. IPD rates in Nunavik remain much higher than in the southern part of the province both in children and adults. More effective pneumococcal vaccines are needed to eliminate geographic disparities in IPD risk.
Quebec Heart and Lung Institute Research Centre, Quebec City, Canada ; Department of Social and Preventive Medicine, Laval University, Quebec City, Canada.
Jean-Baptiste
JB
Le Meur
Quebec Public Health Laboratory (Laboratoire de santé publique du Québec), Quebec National Institute of Public Health (Institut national de santé publique du Québec), Ste-Anne-de-Bellevue, Canada.
Brigitte
B
Lefebvre
Public Health Directorate, Nunavik Regional Board of Health and Social Services, Kuujjuaq, Canada.
Jean-François
JF
Proulx
Public Health Directorate, Nunavik Regional Board of Health and Social Services, Kuujjuaq, Canada.
Serge
S
Déry
Department of Microbiology and Infectious Diseases, University of Sherbrooke, Sherbrooke, Canada ; Etienne-Lebel Research Centre, Sherbrooke University Hospital, Sherbrooke, Canada.
Jacques
J
Pépin
Quebec Heart and Lung Institute Research Centre, Quebec City, Canada ; Department of Social and Preventive Medicine, Laval University, Quebec City, Canada ; Etienne-Lebel Research Centre, Sherbrooke University Hospital, Sherbrooke, Canada.
Philippe
P
De Wals
D000367:Age Factors; D015331:Cohort Studies; D004196:Disease Outbreaks / Q000517:prevention & control*; D005260:Female; D006801:Humans; D015994:Incidence; D004930:Inuit; D008297:Male; D011008:Pneumococcal Infections / Q000453:epidemiology / Q000517:prevention & control; D022242:Pneumococcal Vaccines / Q000008:administration & dosage*; D011018:Pneumonia, Pneumococcal / Q000453:epidemiology / Q000517:prevention & control*; D011634:Public Health; D011792:Quebec / Q000453:epidemiology; D012042:Registries; D012189:Retrospective Studies; D018570:Risk Assessment; D012737:Sex Factors; D014611:Vaccination / Q000379:methods*
C414006:23-valent pneumococcal capsular polysaccharide vaccine; D022242:Pneumococcal Vaccines
Inuit; Streptococcus pneumonia; epidemiology; immunization; paediatric vaccine