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. Author manuscript; available in PMC: 2013 Sep 1.
Published in final edited form as: Pediatr Infect Dis J. 2012 Sep;31(9):964–969. doi: 10.1097/INF.0b013e318263280e

Table 1.

Comparison of geometric mean and geometric mean ratio of antibody titers (GMT) before and 1 month after receipt of trivalent inactivated influenza vaccine (TIV) or placebo in year 1 (2008–2009) and year 2 (2009–2010) in 39 children who received TIV in year 2 (2009–2010).

Group n Pre-dose 1 p-valuea Post-dose 1 p-valuea Pre-dose 2 p-valuea Post-dose 2 p-valuea
Seasonal A(H1N1)b
Geometric mean titer TIV-TIVc 23 20 0.20 1714 <0.01 192 <0.01 270 0.12
PL-TIVd 16 37 62 28 562
Proportion titer ≥40 TIV-TIVc 23 0.48 0.33 0.91 0.63 0.87 0.03 0.87 0.44
PL-TIVd 16 0.69 0.81 0.50 0.99
Proportion titer≥160 TIV-TIVc 23 0.09 0.66 0.91 <0.01 0.74 0.01 0.83 0.64
PL-TIVd 16 0.19 0.44 0.25 0.93
Geometric mean ratio of
post-dose to pre-dose		 TIV-TIVc 23 85.7 <0.01 1.4 <0.01
PL-TIVd 16 1.7 19.9
Proportion ratio ≥4 TIV-TIVc 23 0.83 <0.01 0.17 <0.01
PL-TIVd 16 0.19 0.69
Proportion ratio ≥8 TIV-TIVc 23 0.83 <0.01 0.09 <0.01
PL-TIVd 16 0.12 0.62
Seasonal A(H3N2)b
Geometric mean titer TIV-TIVc 23 18 0.02 859 0.01 45 0.33 243 <0.01
PL-TIVd 16 103 140 26 819
Proportion titer ≥40 TIV-TIVc 23 0.39 0.14 0.91 0.63 0.65 0.54 0.95 0.84
PL-TIVd 16 0.69 0.81 0.50 1.00
Proportion titer≥160 TIV-TIVc 23 0.22 0.48 0.87 0.06 0.30 0.65 0.86 0.35
PL-TIVd 16 0.38 0.56 0.19 1.00
Geometric mean ratio of
post-dose to pre-dose		 TIV-TIVc 23 47.0 <0.01 5.4 <0.01
PL-TIVd 16 1.4 31.6
Proportion ratio ≥4 TIV-TIVc 23 0.91 <0.01 0.65 0.09
PL-TIVd 16 0.12 0.94
Proportion ratio ≥8 TIV-TIVc 23 0.78 <0.01 0.34 <0.01
PL-TIVd 16 0.06 0.88
Seasonal Bb
Geometric mean titer TIV-TIVc 23 292 0.04 1444 <0.01 11 0.57 73 1.00
PL-TIVd 16 118 123 9 73
Proportion titer ≥40 TIV-TIVc 23 0.96 1.00 1.00 0.41 0.22 0.86 0.78 0.80
PL-TIVd 16 0.94 0.94 0.19 0.69
Proportion titer≥160 TIV-TIVc 23 0.74 0.23 0.96 <0.01 0.04 0.85 0.49 0.88
PL-TIVd 16 0.50 0.50 0.00 0.56
Geometric mean ratio of
post-dose to pre-dose		 TIV-TIVc 23 4.9 <0.01 6.5 0.76
PL-TIVd 16 1.0 8.0
Proportion ratio ≥4 TIV-TIVc 23 0.61 <0.01 0.65 0.83
PL-TIVd 16 0.00 0.56
Proportion ratio ≥8 TIV-TIVc 23 0.35 0.01 0.60 1.00
PL-TIVd 16 0.00 0.56
Pandemic A(H1N1)b
Geometric mean titer TIV-TIVc 23 7 0.93 8 0.03 11 0.66 65 0.06
PL-TIVd 16 6 6 9 20
Proportion titer ≥40 TIV-TIVc 23 0.00 1.00 0.00 1.00 0.22 0.75 0.63 0.44
PL-TIVd 16 0.00 0.00 0.12 0.45
Proportion titer≥160 TIV-TIVc 23 0.00 1.00 0.00 1.00 0.09 0.88 0.58 0.11
PL-TIVd 16 0.00 0.00 0.12 0.26
Geometric mean ratio of
post-dose to pre-dose		 TIV-TIVc 23 1.3 0.06 6.1 0.09
PL-TIVd 16 1.0 2.3
Proportion ratio ≥4 TIV-TIVc 23 0.04 1.00 0.55 0.31
PL-TIVd 16 0.00 0.32
Proportion ratio ≥8 TIV-TIVc 23 0.00 1.00 0.46 0.63
PL-TIVd 16 0.00 0.32
a

P-values comparing between TIV-TIV and PL-TIV were obtained by the Chi-square test, Fisher’s Exact test, Wilcoxon-signed rank test or Wald test where appropriate.

b

Antibody titers measured by hemagglutination inhibition assays to A/Brisbane/59/2007 (H1N1), A/Brisbane/10/2007-like virus A/Uruguay/716/2009 (H3N2), B/Florida/4/2006, A/California/7/2009 (H1N1) viruses in year 1;A/Brisbane/59/2007 (H1N1), A/Uruguay/716/2009 (H3N2), B/Brisbane/60/2008, A/California/7/2009 (H1N1) viruses in year 2 (see methods for details of strains used).

c

The TIV-TIV group consists of subjects who received TIV in 2008–2009 and 2009–10. The 2008–09 TIV (year 1) included A/Brisbane/59/2007-like (H1N1), A/Brisbane/10/2007-like (H3N2) and B/Florida/4/2006-like strains. The 2009–10 TIV (year 2) included A/Brisbane/59/2007-like (H1N1), A/Brisbane/10/2007-like (H3N2) and B/Brisbane/60/2008 strains.

d

The PL-TIV group consists of subjects who received placebo in 2008–2009 and TIV in 2009–10.