Protection of trivalent inactivated influenza vaccine against hospitalizations among pandemic influenza A (H1N1) cases in Argentina

Pandemic influenza A(H1N1)pdm09: risk of infection in primary healthcare workers

“…infection with influenza A(H1N1)pdm09 is uncertain, and a range of estimates have been made, which range from indicating protection, [10][11][12][13] to no effect, [14][15][16][17][18][19][20][21][22][23] to increased susceptibility. [24][25][26] A recent meta-analysis found that prior receipt of seasonal influenza vaccination may have been associated with moderate protection against influenza A(H1N1)pdm09.…”

“…38 However, the observational design of the Canadian study, like the present one, means that the association may be due to confounding or bias. 39 A protective effect of seasonal vaccination against influenza A(H1N1)pdm09 infection has been demonstrated in observational studies from Mexico, Argentina, and the US; [10][11][12][13] while other observational studies, 15,16,40 and a randomised controlled trial, 14 have shown no association. A 2012 meta-analysis including 13 studies found no association, but when studies judged to have a moderate or high risk of bias were excluded from the analysis (leaving eight studies), a protective effect on laboratoryconfirmed infection was observed.…”

Partial protection against 2009 pandemic influenza A (H1N1) of seasonal influenza vaccination and related regional factors: Updated systematic review and meta-analyses

“…For the non-randomized studies, based on the NOS scoring system, 3 of the cohort studies had moderate risk, whereas one study 22 had high risk of bias. For the case-control studies, 9 had low-risk bias 8,9,10,14,15,24,28,29,31 , while the other 11 had moderate-risk bias [5][6][7]13,15,[25][26][27]30,32 . The details of the quality assessment are shown in the Supplemental Tables 5-8.…”

“…2,3 More than 200 countries and areas have been affected and over 18000 people have died during the pandemic. 4 Several studies [5][6][7][8][9][10][11][12] have reported on the protective effect of seasonal influenza vaccine against the 2009 pandemic influenza infection. Although some reports presented significant results, 5-10 the cross-protection of seasonal influenza vaccine remains controversial.…”

“…6 In this review, we divided the study by Skowronski et al 15 into one cohort study and 3 case-control studies (Quebec household transmission study as Skowronski-a, national sentinel monitoring system as Skowronski-b, Quebec population case-control study as Skowronski-c, Ontario test-negative case-control study as Skowronskid). This systematic review included 4 RCTs, 11,12,18,19 4 cohort studies, 15,16,22,23 and 20 case-control studies [5][6][7][8][9][10][13][14][15][24][25][26][27][28][29][30][31][32] . In addition, 2 surveillance reports and one outbreak investigation were included.…”