Component‐Specific Effectiveness of Trivalent Influenza Vaccine as Monitored through a Sentinel Surveillance Network in Canada, 2006–2007

Abstract

Sentinel surveillance provides a broad platform to link new variant detection and the composite of circulating viruses to annual monitoring of component-specific VE.

Interim estimates of 2013/14 vaccine effectiveness against influenza A(H1N1)pdm09 from Canada’s sentinel surveillance network, January 2014

“…Proportions comparable to previous community surveys were also observed in 2013/14 for receipt of the 2009 monovalent A(H1N1)pdm09 vaccine (43% versus 41%) [17]. The proportion of participants with co-morbidity was comparable to previous Canadian estimates (15-20%) [3,[6][7][8][9][10][11][12]18] (Table 2). The adjusted VE estimate for any influenza, driven predominately by A(H1N1)pdm09, was 71% (95% CI: 54-81), and for A(H1N1)pdm09 alone was 74% (95% CI: 58-83) ( Table 4).…”

“…After applying exclusions related to immunisation timing, 29% of controls and 10% of cases were considered immunised (p<0.01) ( Table 2). The proportion of controls reporting TIV receipt in 2013/14 and earlier seasons was comparable to that reported in previous VE analyses and other community-based surveys in Canada (ca 30%) [3,[7][8][9]11,12,16]. Proportions comparable to previous community surveys were also observed in 2013/14 for receipt of the 2009 monovalent A(H1N1)pdm09 vaccine (43% versus 41%) [17].…”

“…As in previous seasons, adults 20-49 years old contributed the largest proportion of specimens (50%) ( Table 2) [3,[6][7][8][9][10][11][12]. However, compared with the 2012/13 mid-season publication [3], a greater proportion of cases in 2013/14 were adults aged 20-49 years (53% versus 42%; p<0.01) or 50-64 years (22% versus 17%; p=0.13) (p<0.01 combined); proportions were more comparable among controls (48% versus 43%; p=0.17 and 20% versus 21%; p=0.86, respectively) ( Table 2).…”

“…As previously described [3,[5][6][7][8][9][10][11][12], a test-negative casecontrol design was used to estimate VE. Patients presenting with influenza-like illness (ILI) and testing positive for influenza viruses were considered cases, and those testing negative were considered controls.…”

“…Findings were expressed as percentage identity to vaccine, calculated as (1− (number of aa substitutions in antigenic sites)/(total antigenic site aa residues))x100%. After removal of the signal peptide (residues [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17], the approximate likelihood method was used to generate the phylogenetic tree of aligned nucleotide sequences in FastTree [14], visualised in FigTree [15], including reference HA sequences shown in Table 1.…”