Table 1.
Risks of thyroid dysfunction in the 56-day risk period following the first or second dose of COVID-19 vaccination
| Outcomes | CoronaVac | BNT162b2 | ||||||
|---|---|---|---|---|---|---|---|---|
| No. of event | Person years | IRR | 95% CI | No. of event | Person years | IRR | 95% CI | |
| Initiation of ATD | ||||||||
| Baseline | 3116 | 1878.3 | 1.00 | - | 3299 | 2000.0 | 1.00 | - |
| 0 to 55 days: first dose | 109 | 74.5 | 0.707 | (0.549, 0.912) | 130 | 76.4 | 0.864 | (0.670, 1.114) |
| 0 to 55 days: second dose | 182 | 99.3 | 0.879 | (0.693, 1.116) | 216 | 119.1 | 0.972 | (0.770, 1.227) |
| Initiation of LT4 | ||||||||
| Baseline | 5315 | 3131.6 | 1.00 | - | 5575 | 3280.4 | 1.00 | - |
| 0 to 55 days: first dose | 167 | 125.6 | 0.778 | (0.618, 0.981) | 144 | 118.6 | 0.911 | (0.716, 1.159) |
| 0 to 55 days: second dose | 217 | 175.4 | 0.768 | (0.613, 0.962) | 288 | 219.2 | 1.019 | (0.833, 1.246) |
| Hyperthyroidism (TSH < 0.35 mIU/L) | ||||||||
| Baseline | 11423 | 6896.8 | 1.00 | - | 11781 | 7141.6 | 1.00 | - |
| 0 to 55 days: first dose | 354 | 214.5 | 0.830 | (0.713, 0.967) | 345 | 201.5 | 0.872 | (0.744, 1.023) |
| 0 to 55 days: second dose | 505 | 286.5 | 0.911 | (0.786, 1.055) | 619 | 333.6 | 1.039 | (0.899, 1.201) |
| Hypothyroidism (TSH > 4.8 mIU/L) | ||||||||
| Baseline | 8707 | 5250.1 | 1.00 | - | 8941 | 5419.6 | 1.00 | - |
| 0 to 55 days: first dose | 300 | 172.3 | 0.963 | (0.807, 1.149) | 307 | 158.9 | 1.002 | (0.838, 1.199) |
| 0 to 55 days: second dose | 380 | 231.6 | 0.945 | (0.799, 1.119) | 463 | 270.7 | 0.935 | (0.794, 1.102) |
| Graves’ disease | ||||||||
| Baseline | 288 | 171.9 | 1.00 | - | 325 | 199.5 | 1.00 | - |
| 0 to 55 days: first dose | 3 | 5.2 | NA | NA | 21 | 9.0 | 1.105 | (0.534, 2.289) |
| 0 to 55 days: second dose | 15 | 7.2 | NA | NA | 21 | 12.6 | 0.823 | (0.424, 1.599) |
| Thyroiditis | ||||||||
| Baseline | 60 | 37.0 | 1.00 | - | 60 | 38.2 | 1.00 | - |
| 0 to 55 days: first dose | 4 | 2.1 | NA | NA | 6 | 1.7 | NA | NA |
| 0 to 55 days: second dose | 6 | 3.0 | NA | NA | 5 | 2.9 | NA | NA |
ATD anti-thyroid drug, LT4 levothyroxine, IRR incidence rate ratio, CI confidence interval, TSH thyroid-stimulating hormone, NA not available if the number of events in one of the risk periods were ≤ 5