Impact of a mass immunization campaign to cotrol an outbreak of severe respiratory infections in Nunavik, northern Canada

Abstract

Objectives. In spring 2002, a mass immunization campaign using a 23-valent pneumococcal polysaccharide vaccine (23-PPV) was launched in order to control an outbreak of severe pneumonia caused by a virulent clone of serotype 1 Streptococcus pneumoniae in Nunavik, Quebec, Canada. The objective of the study was to evaluate the impact of this campaign on the incidence of invasive pneumococcal disease (IPD) and hospitalizations possibly associated with pneumococcal infections (HPAPI) in the mostly Inuit population aged 10 to 64 years. Study design. Retrospective analysis of surveillance and administrative data. Methods. Multivariate Poisson model comparing the frequency rates of selected outcomes before the outbreak, during the outbreak, and after implementation of the mass immunization program. Results. The reported incidence of serotype 1 IPD decreased markedly after the implementation of the vaccination campaign (rate ratio = 0.16; p < 0.002). The frequency of HPAPI and the mean duration of hospital stay also decreased. However, vaccine failures were documented and the HPAPI rate remained higher than in the period prior to the outbreak. Conclusions. Although 23-PPV contributed to control the outbreak, better vaccines are needed for the prevention of infections caused by serotype 1 S. pneumoniae. (Int J Circumpolar Health 2006; 65(4): 297-304).

Invasive Bacterial Diseases in Northern Canada

“…Although this rate is lower than that seen in the earlier period (1999)(2000)(2001)(2002)34.0/100,000 population), additional data will be needed to determine if the decreasing trend is sustained. The decrease in the disease incidence may be partly attributed to PCV7 programs, as well as the mass pneumococcal polysaccharide vaccination campaigns launched in 2001 and 2002 in response to outbreaks of serotype 1 disease in parts of the region, which reduced the occurrence of this predominant serotype in subsequent years (20,21). Reduction in the number of cases among children <2 years of age in regions where universal infant PCV7 programs were implemented in 2002 (northern Québec and Nunavut) is an early indicator of the effect of the vaccination program.…”

“…However, the enhanced nature of the surveillance system and regular data audits represent improvements over routine passive surveillance. Laboratory specimens may not have been taken before initiation of empiric treatment, and collection and transportation of clinical specimens are diffi cult in remote areas experiencing extreme temperatures (20,21). Unfortunately, because vaccine registries have not yet been fully implemented in Canada, immunization coverage rates are not available.…”

Molecular Characterization of Streptococcus pneumoniae Serotype 12F Isolates Associated with Rural Community Outbreaks in Alaska

“…In this outbreak, 17 cases occurred over a 21-month period and recommendations for increased use of the polysaccharide vaccine were made. While antimicrobial chemoprophylaxis is likely to be useful in the management of small, short-lived, closed-population outbreaks (27), vaccine options might be a more useful alternative in community outbreaks, which are likely to be of longer duration and involve larger populations (7,28). The 23-valent pneumococcal vaccine has reasonable efficacy against 12F IPD in healthy adults but is not likely to be useful for infants or the very elderly (29,30).…”

International Circumpolar Surveillance System for Invasive Pneumococcal Disease, 1999–2005

“…Serotype distribution (all age groups combined) has changed; however, serotype 1 (24%) continues to be the most prevalent serotype, followed by 8 (11%), 3 (7%), 10A/18C/22F (6%), and 6B (5%). Two regions in northern Canada had outbreaks of serotype 1 during the surveillance period, which may have affected relative frequencies of serotypes (8)(9)(10).…”