OR of influenza-like illness in patients who tested positive for A-H1N1 virus
| Cases (11) | Controls (24) | Crude OR (CI 95%) | |
| Any flu vaccines* | 3 | 7 | 0.9 (0.1 to 5.5) |
| A-H1N1 vaccine | 0 | 3 | – |
| Seasonal vaccine | 2 | 6 | 0.7 (0.1 to 5.3) |
| Not vaccinated | 8 | 17 | Reference |
Cases: patients with influenza-like illness (ILI) who tested positive for the A-H1N1 virus; controls: ILI patients who tested negative for the A-H1N1 virus.
↵* In one case and one control, the type of vaccine was not specified.