Table 2.
Vaccine Safety Datalink Rapid Cycle and End-of-Season Analysis Results
| Analysis | Early Analysis (December 9, 2018) | End-of-Season Analysis (April 3, 2019) | |
|---|---|---|---|
| Number of IIV3-HD Administrations | 614 200 | 645 362 | |
| Sequential self-controlled risk interval analysis | GBS casesa in days 1–42 postvaccination (risk window) | 5 | - |
| GBS casesa in days 43–84 postvaccination (control window) | 0 | - | |
| Relative risk | 11 | - | |
| LLR/critical value | 3.47/3.39 | - | |
| Nonsequential self-controlled risk interval analysis | Chart-confirmed GBS cases in days 1–42 postvaccination (risk window) | - | 1 |
| Chart-confirmed GBS cases in days 43–84 postvaccination (control window) | - | 1 | |
| Relative risk | - | 1 | |
| 95% CI | - | (0.06–15.99) | |
| Current-vs-historical Poisson analysis | Observed GBS casesa | 6 | 8 |
| Expected GBS casesb | 3.89 | 4.99 | |
| Relative risk | 1.54 | 1.6 | |
| LLR/critical value | 0.49/3.03 | 0.76/3.03 |
Abbreviations: CI, confidence interval; GBS, Guillain-Barré syndrome; IIV3-HD, High-dose influenza vaccine; LLR, log-likelihood ratio of the maximized sequential probability ratio test.
a International Classification of Diseases, Tenth Revision (ICD-10) coded cases.
bExpected GBS cases were calculated based on site-specific historical rates (combined rate across all sites: 9.04 per million vaccinations in ages ≥65 years). International Classification of Diseases, Nineth Revision and ICD-10 coded cases.