Table 3.
Associated between influenza vaccination and the risk of COVID-19 clinical outcomes by random-effects model.
| Hospitalization | ICU admission | Ventilator support | Death | |||||||||||||
| Studies | n | Sample size | OR (95% CI) | I2 (%) | n | Sample size | OR (95% CI) | I2 (%) | n | Sample size | OR (95% CI) | I2 (%) | n | Sample size | OR (95% CI) | I2 (%) |
| All | 9 | 57,424 | 0.87 (0.68–1.10) | 79 | 10 | 83,838 | 0.83 (0.72–0.96)∗ | 61 | 8 | 55,672,128 | 0.69 (0.57–0.84)∗ | 69 | 15 | 139,342† | 0.69 (0.52–0.93)∗ | 87 |
| Population | ||||||||||||||||
| General | 8 | 54,045 | 0.86 (0.66–1.12) | 82 | 9 | 82,299 | 0.91 (0.87–0.96)∗ | 39‡ | 5 | 2585 | 0.82 (0.76–0.88)∗ | 43‡ | 14 | 137,678† | 0.74 (0.55–1.00) | 86 |
| Elders | 3 | 1365† | 1.00 (0.82–1.22) | 0‡ | 4 | 1365† | 1.06 (0.71–1.56) | 37‡ | 2 | 1093 | 0.96 (0.42–2.17) | 64 | 3 | 406† | 1.35 (0.91–1.99) | 0‡ |
| Pregnant women | 0 | NA | NA | NA | 0 | NA | NA | NA | 0 | NA | NA | NA | 2 | 1724 | 0.35 (0.25–0.48)∗ | 0‡ |
| Study design | ||||||||||||||||
| Cohort study | 9 | 57,424 | 0.87 (0.68–1.10) | 79 | 10 | 83,838 | 0.83 (0.72–0.96)∗ | 61 | 6 | 3538 | 0.72 (0.54–0.96)∗ | 66 | 14 | 138,782 | 0.70 (0.51–0.97)∗ | 88 |
| Cross-sectional study | 0 | NA | 0 | NA | 2 | 55,667,988 | 0.72 (0.68–0.76)∗ | 49‡ | 0 | NA | ||||||
∗
P < 0.05.
†
The actual sample size was larger, since the sample size in some of the original studies was not available for the subgroup analysis.
‡
The pooled OR was calculated by a fixed-effects model. CI: Confidence interval; COVID-19: Corona virus disease 2019; ICU: Intensive care unit; n: Number of studies; NA: Not available; OR: Odds ratio.