| Infection with any virus | Myalgia | 3.62 (1.29 to 10.12) | 0.01 |
| Influenza vaccine (May–October) | 0.11 (0.02 to 0.61) | 0.01 |
| Influenza vaccine (November–April) | 1.21 (0.25 to 5.95) | 0.81 |
| Influenza infection | Age (per 1 year increase) | 1.20 (1.04 to 1.38) | 0.01 |
| Infection in May–October | 57.40 (1.03 to 3209.38) | 0.05 |
| Influenza vaccine | 0.001 (<0.0001 to 0.33) | 0.02 |
| Myalgia | 190.72 (3.68 to 9891.91) | 0.009 |
| Neutrophilia | 0.03 (0.001 to 0.60) | 0.02 |
| Rhinovirus infection | Infection in May–October | 0.39 (0.14 to 1.07) | 0.07 |
| Neutrophilia | 9.93 (1.19 to 82.83) | 0.03 |
| Pneumococcal infection | Rigors | 2.61 (1.06 to 6.44) | 0.04 |
| Current smoking | 4.04 (1.33 to 12.28) | 0.01 |