Effectiveness of a mass immunization campaign against serogroup C meningococcal disease in Quebec

Philippe De Wals, Gaston De Serres, Théophile Niyonsenga

Research output: Contribution to journalArticle

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Abstract

Context: An outbreak of meningococcal disease in Quebec province prompted a mass immunization program. The impact of this campaign on the epidemiology of meningococcal disease has not been studied. Objectives: To study the impact of a mass immunization campaign using polysaccharide vaccine on the epidemiology of meningococcal disease (MCD) and to assess serogroup C vaccine effectiveness (VE). Design, Setting, and Subjects: Analysis of MCD cases reported in Quebec from 1990 to 1998, before and after the mass immunization campaign was conducted during the winter of 1992-1993, when 84% of residents aged 6 months to 20 years (the target population, approximately 1.9 million individuals) were vaccinated. Main Outcome Measures: Incidence of MCD in 1990-1998; incidence of cultureproven serogroup C MCD between April 1, 1993, and March 31, 1998, compared among vaccinated and unvaccinated persons in the target population. Results: The incidence of serogroup C disease decreased after the mass immunization campaign, from 1.4 per 100000 in 1990-1992 to 0.3 per 100000 in 1993-1998, and the overall incidence of other serogroups remained stable at 0.7 per 100000, with a small increase in the proportion of cases caused by serogroup Y (P=.009). Protection from serogroup C MCD was indicated in the first 2 years after vaccine administration (VE, 65%; 95% confidence interval [CI], 20%-84%), but not in the next 3 years (VE, 0%; 95% CI, -5% to 65%). Vaccine effectiveness was strongly related to age at vaccination: 83% (95% CI, 39%-96%) for ages 15 through 20 years, 75% (95% CI,-17% to 93%) for ages 10 through 14 years, and 41% (95% CI, -106% to 79%) for ages 2 through 9 years. There was no evidence of protection in children younger than 2 years; all 8 MCD cases in this age group occurred in vaccinees. Conclusions: Serogroup C polysaccharide vaccine is effective for controlling outbreaks in teenaged individuals but should not be used in children younger than 2 years. The mass campaign did not induce significant serogroup switching.

Original languageEnglish
Pages (from-to)177-181
Number of pages5
JournalJournal of the American Medical Association
Volume285
Issue number2
DOIs
Publication statusPublished - 2001
Externally publishedYes

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Mass Vaccination
Quebec
Vaccines
Confidence Intervals
Health Services Needs and Demand
Incidence
Disease Outbreaks
Polysaccharides
Epidemiology
Immunization Programs
Serogroup
Vaccination
Age Groups
Outcome Assessment (Health Care)

Cite this

@article{905d1ef95cbd40188ef2e1d8dda744f1,
title = "Effectiveness of a mass immunization campaign against serogroup C meningococcal disease in Quebec",
abstract = "Context: An outbreak of meningococcal disease in Quebec province prompted a mass immunization program. The impact of this campaign on the epidemiology of meningococcal disease has not been studied. Objectives: To study the impact of a mass immunization campaign using polysaccharide vaccine on the epidemiology of meningococcal disease (MCD) and to assess serogroup C vaccine effectiveness (VE). Design, Setting, and Subjects: Analysis of MCD cases reported in Quebec from 1990 to 1998, before and after the mass immunization campaign was conducted during the winter of 1992-1993, when 84{\%} of residents aged 6 months to 20 years (the target population, approximately 1.9 million individuals) were vaccinated. Main Outcome Measures: Incidence of MCD in 1990-1998; incidence of cultureproven serogroup C MCD between April 1, 1993, and March 31, 1998, compared among vaccinated and unvaccinated persons in the target population. Results: The incidence of serogroup C disease decreased after the mass immunization campaign, from 1.4 per 100000 in 1990-1992 to 0.3 per 100000 in 1993-1998, and the overall incidence of other serogroups remained stable at 0.7 per 100000, with a small increase in the proportion of cases caused by serogroup Y (P=.009). Protection from serogroup C MCD was indicated in the first 2 years after vaccine administration (VE, 65{\%}; 95{\%} confidence interval [CI], 20{\%}-84{\%}), but not in the next 3 years (VE, 0{\%}; 95{\%} CI, -5{\%} to 65{\%}). Vaccine effectiveness was strongly related to age at vaccination: 83{\%} (95{\%} CI, 39{\%}-96{\%}) for ages 15 through 20 years, 75{\%} (95{\%} CI,-17{\%} to 93{\%}) for ages 10 through 14 years, and 41{\%} (95{\%} CI, -106{\%} to 79{\%}) for ages 2 through 9 years. There was no evidence of protection in children younger than 2 years; all 8 MCD cases in this age group occurred in vaccinees. Conclusions: Serogroup C polysaccharide vaccine is effective for controlling outbreaks in teenaged individuals but should not be used in children younger than 2 years. The mass campaign did not induce significant serogroup switching.",
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Effectiveness of a mass immunization campaign against serogroup C meningococcal disease in Quebec. / De Wals, Philippe; De Serres, Gaston; Niyonsenga, Théophile.

In: Journal of the American Medical Association, Vol. 285, No. 2, 2001, p. 177-181.

Research output: Contribution to journalArticle

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N2 - Context: An outbreak of meningococcal disease in Quebec province prompted a mass immunization program. The impact of this campaign on the epidemiology of meningococcal disease has not been studied. Objectives: To study the impact of a mass immunization campaign using polysaccharide vaccine on the epidemiology of meningococcal disease (MCD) and to assess serogroup C vaccine effectiveness (VE). Design, Setting, and Subjects: Analysis of MCD cases reported in Quebec from 1990 to 1998, before and after the mass immunization campaign was conducted during the winter of 1992-1993, when 84% of residents aged 6 months to 20 years (the target population, approximately 1.9 million individuals) were vaccinated. Main Outcome Measures: Incidence of MCD in 1990-1998; incidence of cultureproven serogroup C MCD between April 1, 1993, and March 31, 1998, compared among vaccinated and unvaccinated persons in the target population. Results: The incidence of serogroup C disease decreased after the mass immunization campaign, from 1.4 per 100000 in 1990-1992 to 0.3 per 100000 in 1993-1998, and the overall incidence of other serogroups remained stable at 0.7 per 100000, with a small increase in the proportion of cases caused by serogroup Y (P=.009). Protection from serogroup C MCD was indicated in the first 2 years after vaccine administration (VE, 65%; 95% confidence interval [CI], 20%-84%), but not in the next 3 years (VE, 0%; 95% CI, -5% to 65%). Vaccine effectiveness was strongly related to age at vaccination: 83% (95% CI, 39%-96%) for ages 15 through 20 years, 75% (95% CI,-17% to 93%) for ages 10 through 14 years, and 41% (95% CI, -106% to 79%) for ages 2 through 9 years. There was no evidence of protection in children younger than 2 years; all 8 MCD cases in this age group occurred in vaccinees. Conclusions: Serogroup C polysaccharide vaccine is effective for controlling outbreaks in teenaged individuals but should not be used in children younger than 2 years. The mass campaign did not induce significant serogroup switching.

AB - Context: An outbreak of meningococcal disease in Quebec province prompted a mass immunization program. The impact of this campaign on the epidemiology of meningococcal disease has not been studied. Objectives: To study the impact of a mass immunization campaign using polysaccharide vaccine on the epidemiology of meningococcal disease (MCD) and to assess serogroup C vaccine effectiveness (VE). Design, Setting, and Subjects: Analysis of MCD cases reported in Quebec from 1990 to 1998, before and after the mass immunization campaign was conducted during the winter of 1992-1993, when 84% of residents aged 6 months to 20 years (the target population, approximately 1.9 million individuals) were vaccinated. Main Outcome Measures: Incidence of MCD in 1990-1998; incidence of cultureproven serogroup C MCD between April 1, 1993, and March 31, 1998, compared among vaccinated and unvaccinated persons in the target population. Results: The incidence of serogroup C disease decreased after the mass immunization campaign, from 1.4 per 100000 in 1990-1992 to 0.3 per 100000 in 1993-1998, and the overall incidence of other serogroups remained stable at 0.7 per 100000, with a small increase in the proportion of cases caused by serogroup Y (P=.009). Protection from serogroup C MCD was indicated in the first 2 years after vaccine administration (VE, 65%; 95% confidence interval [CI], 20%-84%), but not in the next 3 years (VE, 0%; 95% CI, -5% to 65%). Vaccine effectiveness was strongly related to age at vaccination: 83% (95% CI, 39%-96%) for ages 15 through 20 years, 75% (95% CI,-17% to 93%) for ages 10 through 14 years, and 41% (95% CI, -106% to 79%) for ages 2 through 9 years. There was no evidence of protection in children younger than 2 years; all 8 MCD cases in this age group occurred in vaccinees. Conclusions: Serogroup C polysaccharide vaccine is effective for controlling outbreaks in teenaged individuals but should not be used in children younger than 2 years. The mass campaign did not induce significant serogroup switching.

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