ID News: February 2015 (S1)

CCDR

Volume 41S-1, February 20, 2015: Enterovirus D68 and influenza

ID News

EV-D68 and influenza vaccine effectiveness

Shaw J, Welch TR, Milstone AM. The role of syndromic surveillance in directing the public health response to the enterovirus D68 epidemic. JAMA Pediatr. 2014;168(11):981−2. doi:10.1001/jamapediatrics.2014.2628.

“Commercially available multiplex polymerase chain reaction-based respiratory pathogen panels offer rapid detection of common pathogens with high sensitivity and specificity. Because of the nucleic acid sequence similarities between the many types of Rhinovirus and Enterovirus, most of these panels do not distinguish between these 2 virus groups and are therefore typically reported as “Rhinovirus/Enterovirus.” These panels have proved a useful screening test during the current EV-D68 outbreaks as specimens that test positive for Rhinovirus/Enterovirus can prompt further analysis to specifically identify EV-D68 . . . Confirmatory testing relies on partial sequencing of the structural protein gene VP4-VP2 or VP1 region, available in some . . . laboratories.”

Skowronski D, Chambers C, Sabaiduc S, De Seers G, Dickinson J, Winter AL et al. Interim estimates of 2014/15 vaccine effectiveness against influenza A(H3N2) from Canada’s Sentinel Physician Surveillance Network, January 2015, Euro Surveill. 201 Jan 29;19(5).

The 2014/15 influenza season to date in Canada has been characterised by predominant influenza A(H3N2) activity. Canada’s Sentinel Physician Surveillance Network (SPSN) assessed interim vaccine effectiveness (VE) against medically attended, laboratory-confirmed influenza A(H3N2) infection in January 2015 using a test-negative case–control design. Of 861 participants, 410 (48%) were test-positive cases (35% vaccinated) and 451 (52%) were test-negative controls (33% vaccinated). Among test-positive cases, the majority (391; 95%) were diagnosed with influenza A, and of those with available subtype information, almost all influenza A viruses (379/381; 99%) were A(H3N2). Among 226 (60%) A(H3N2) viruses that were sequenced, 205 (91%) clustered with phylogenetic clade 3C.2a, considered genetically and antigenically distinct from the 2014/15 vaccine reference strain... Consistent with substantial vaccine mismatch, little or no vaccine protection was observed overall, with adjusted VE against medically attended influenza A(H3N2) infection of −8% (95% CI: −50 to 23%). Given these findings, other adjunct protective measures should be considered to minimise morbidity and mortality, particularly among high-risk individuals. Virus and/or host factors influencing this reduced vaccine protection warrant further in-depth investigation.

McNeil SA, Andrew MK, Ye L, Haguinet F, Hatchette TF, ElSherif M, LeBlanc J, Ambrose A, McGeer A, McElhaney JE, Loeb M, MacKinnon-Cameron D, Sharma R, Dos Santos G, Shinde V, on behalf of the Investigators of the Serious Outcomes Surveillance Network of the Canadian Immunization Research Network (CIRN). Interim estimates of 2014/15 influenza vaccine effectiveness in preventing laboratory-confirmed influenza-related hospitalisation from the Serious Outcomes Surveillance Networks of the Canadian Immunization Research Network, January 2015. Euro Surveill. 2015;20(5):pii=21024.

The 2014/15 influenza season in Canada has been characterised to date by early and intense activity dominated by influenza A(H3N2). A total of 99.0% (593/599) hospitalisations for laboratory-confirmed influenza with a known influenza virus type enrolled in sentinel hospitals of the Serious Outcomes Surveillance Network of the Canadian Immunization Research Network were due to influenza A. Of the 216 with a known subtype, influenza A(H3N2) accounted for 99.1% (n=214). Interim unmatched vaccine effectiveness (VE) estimates adjusted for age and presence of one or more medical comorbidities were determined by test-negative case–control design to be −16.8% (90% confidence interval (CI): −48.9 to 8.3) overall and −22.0% (90% CI: −66.5 to 10.7) for laboratory-confirmed influenza A(H3N2). Among adults aged under 65 years, the overall VE was 10.8% (90% CI: −50.2 to 47.0) while in adults aged 65 years or older, the overall VE was −25.4% (90% CI: −65.0 to 4.6).

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