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. 2009 Dec 4;171(2):177–188. doi: 10.1093/aje/kwp345

Table 3.

Results of Sequential Testing for Influenza Vaccine Safety as of Each Season's Final Surveillance Week, Vaccine Safety Datalink Project, 2005/06–2007/08

Adverse Event Category and Age Groupa Influenza Season No. of Vaccine Doses Administered No. of Cases
 Upper Limit of No. of Events No. of Cases
 Self-Controlled Case Series Analysis
 Difference-in-Difference Analysis
In Current Risk Period In Current Control Period In Historical Risk Periods In Historical Control Periods RR LLRb Critical Value of LLR RRR LLRb Critical Value of LLR
Seizure
    Children 2005/06 317,108 58 43 120 133 149 1.35 1.12 5.37 1.51 2.13 5.26
2006/07 415,446 51 64 200 191 192 0.80 5.51 0.80 5.51
2007/08 462,998 55 56 200 243 257 0.98 5.51 1.04 0.02 5.40
    Adults 2005/06c 1,429,974 199 201 400 605 724 0.99 5.55 1.18 1.44 5.54
2006/07 1,598,880 153 160 500 808 933 0.96 5.56 1.10 0.38 5.62
2007/08 1,742,858 168 154 500 965 1,104 1.09 0.30 5.56 1.25 1.98 5.59
Meningoencephalitis, all ages 2005/06 1,749,326 23 87 120 71 319 0.76 5.40 1.19 0.26 5.11
2006/07 2,014,326 21 53 150 94 406 1.13 0.11 5.40 1.71 1.99 5.06
2007/08 2,205,856 22 71 150 115 459 0.89 5.40 1.24 0.37 5.17
Bell's palsy
    Children 2005/06 317,108 8 17 40 28 39 0.67 5.01 0.66 5.14
2006/07 415,446 19 15 50 36 56 1.81 1.49 5.24 1.97 1.94 4.92
2007/08 462,998 16 18 50 55 71 1.27 0.24 5.24 1.15 0.08 4.97
    Adults 2005/06 1,432,218 271 365 800 1,025 1,473 1.06 0.27 5.72 1.07 0.33 5.70
2006/07 1,598,880 300 399 800 1,296 1,838 1.07 0.44 5.72 1.07 0.35 5.72
2007/08 1,742,858 311 447 1,000 1,596 2,237 0.99 5.77 0.98 5.81
Other cranial nerve disorder
    Children 2005/06 317,108 3 4 20 11 23 1.07 0.00 4.53 1.57 0.17 4.51
2006/07 415,446 6 9 25 14 27 0.95 4.72 1.29 0.11 4.68
2007/08 462,998 3 11 25 20 36 0.39 4.72 0.49 4.94
    Adults 2005/06c 1,416,883 337 466 800 1,172 1,582 1.03 0.10 5.72 0.97 5.75
2006/07 1,598,880 391 532 1,000 1,512 2,051 1.05 0.27 5.77 1.00 5.81
2007/08 1,742,858 374 544 1,200 1,903 2,583 0.98 5.81 0.93 5.84
Demyelinating disease
    Children 2005/06 317,108 3 2 15 15 11 2.14 0.36 4.49 1.10 0.01 4.41
2006/07 415,446 1 3 20 18 13 0.48 4.53 0.24 4.81
2007/08 462,998 3 5 15 19 16 0.86 4.49 0.51 4.28
    Adults 2005/06 1,432,218 171 298 600 753 1,189 0.82 5.65 0.91 5.68
2006/07 1,598,880 201 325 600 924 1,487 0.88 5.65 1.00 5.75
2007/08 1,742,858 194 347 800 1,125 1,812 0.80 5.72 0.90 5.76
Disorder of the peripheral nervous system
    Children 2005/06 317,108 9 22 50 46 56 0.58 5.24 0.50 5.01
2006/07 415,446 10 20 60 55 78 0.71 5.24 0.71 5.23
2007/08 462,998 19 27 80 65 98 1.01 5.32 1.06 0.02 5.26
    Adults 2005/06c 569,039 938 1,524 2,000 7,893 11,642 0.88 5.95 0.91 5.89
2006/07c 601,861 1,007 1,482 2,000 10,212 14,918 0.97 5.95 0.99 5.90
2007/08c 581,324 887 1,355 2,000 12,792 18,542 0.94 5.95 0.95 5.93
Ataxia, all ages 2005/06 1,749,326 13 27 80 86 105 0.69 5.32 0.59 5.20
2006/07 2,014,326 27 38 80 99 132 1.02 0.00 5.32 0.95 5.08
2007/08 2,205,856 35 36 80 126 170 1.39 0.95 5.32 1.31 0.65 5.12
Anaphylaxisd, all ages 2005/06 1,749,326 3 1 12 2 6 3.00 0.52 4.27 N/A
2006/07 2,014,326 4 1 12 5 7 4.00 0.96 4.27 N/A
2007/08 2,205,856 1 1 12 9 8 1.00 0.00 4.27 N/A
Allergic reaction other than anaphylaxise
    Children 2005/06 319,203 49 52 150 162 122 0.94 5.45 0.71 5.35
2006/07 418,081 96 70 200 211 174 1.37 2.04 5.51 1.13 0.31 5.41
2007/08 459,263 104 70 200 307 244 1.49 3.34 5.51 1.18 0.58 5.37
    Adults 2005/06 1,466,842 137 98 300 459 376 1.40 3.25 5.55 1.15 0.53 5.44
2006/07 1,635,562 156 125 300 596 474 1.25 1.71 5.55 0.99 5.51
2007/08 1,746,619 196 164 400 752 599 1.20 1.42 5.55 0.95 5.61
Expected No. of Cases Based on Historical Risk Periods Poisson-based Analysis
RR LLRb Critical Value of LLR
Guillian-Barré syndromee, all ages 2005/06 1,788,108 12 15 14.4 0.83 3.57
2006/07c 1,960,430 17 15 15.1 1.13 0.12 3.57
2007/08 2,214,335 23 20 16.7 1.37 1.05 3.63

Abbreviations: LLR, log-likelihood ratio; N/A, not applicable; RR, relative risk; RRR, relative risk ratio.

a

Age groups: all ages, ≥6 months; children, 6 months–17 years; adults, ≥18 years.

b

Since the statistical tests were 1-sided, the LLR was not calculated when the RR was less than 1.0.

c

Current season results for these adverse events are presented as of the week the upper limit was reached, not as of the end of surveillance.

d

Difference-in-difference analyses were not conducted for anaphylaxis, since there were fewer than 25 cases in the risk and control periods in previous seasons.

e

Analyses for allergic reactions and Guillian-Barré syndrome were conducted after the analyses for the other categories. Because of the dynamic nature of the data source, the dose counts for these categories fluctuated in comparison with those for the other categories.