Table 1.
Characteristics of patients infected with SARS‐CoV‐2 the Omicron BA.1 and BA.2 variants from December 27, 2021 to February 14, 2022.
| Variables | BA.1 | BA.2 | p * | ||
|---|---|---|---|---|---|
| N = 2793 | N = 207 | ||||
| n | % | n | % | ||
| Age (years) | |||||
| Median | 36 | 39 | 0.08 | ||
| Interquartile | 25–51 | 24–59 | |||
| Range | 0–94 | 0–99 | |||
| Age group (years) | |||||
| <45 | 1803 | 64.5 | 126 | 60.9 | 0.002 |
| 45–64 | 745 | 26.7 | 50 | 24.1 | |
| 65–79 | 198 | 7.1 | 19 | 9.2 | |
| >80 | 47 | 1.7 | 12 | 5.8 | |
| Gender | |||||
| Female | 1559 | 55.8 | 113 | 54.6 | 0.73 |
| Male | 1234 | 44.2 | 94 | 45.4 | |
| COVID‐19 vaccination status1497, 76 | |||||
| Not vaccinated | 51 | 3.4 | 2 | 2.6 | 1.0 |
| Vaccinated | 1446 | 96.6 | 74 | 97.4 | |
| Number of vaccine injections among vaccinated patients1446, 74 | |||||
| One dose | 144 | 10.0 | 11 | 14.9 | 0.19 |
| Two doses | 905 | 62.3 | 38 | 51.3 | |
| Three doses | 395 | 27.3 | 25 | 33.8 | |
| Four doses | 2 | 0.1 | 0 | 0 | |
| Number of vaccine injections (not vaccinated vs. two or three doses)1351, 65 | |||||
| Not vaccinated | 51 | 3.8 | 2 | 3.1 | 1.0 |
| Vaccinated with two or three doses | 1300 | 96.2 | 63 | 96.9 | |
| The median time between the last vaccine injection and positive SARS‐CoV‐2 PCR (min, max) (days)934, 53 | 117 (0 – 375) | 83 (9 – 208) | 0.13 | ||
| Time range between last vaccine injection and positive SARS‐CoV‐2 PCR (days)922, 53 | |||||
| ≤21 | 123 | 13.3 | 3 | 5.7 | 0.11 |
| >21 | 799 | 86.7 | 50 | 94.3 | |
| Hospitalization | |||||
| No | 2755 | 98.6 | 194 | 93.7 | <0.0001 |
| Yes | 38 | 1.4 | 13 | 6.3 | |
| Transfer to the intensive care unit | |||||
| No | 2737 | 98.0 | 207 | 92.3 | 1.0 |
| Yes | 3 | 0.1 | 0 | 0 | |
| Death | |||||
| No | 2783 | 99.6 | 204 | 98.5 | 0.06 |
| Yes | 10 | 0.4 | 3 | 1.5 | |
Note: Superscript numbers indicate the number of patients for whom data were available.
Abbreviations: PCR, polymerase chain reaction; SARS‐CoV‐2, severe acute respiratory syndrome coronavirus 2.
Statistical analyses were carried out using Stata version 16.0 (http://www.stata.com). The Pearson's χ 2 test and Fisher's exact test, as appropriate, were applied to analyze the categorical variables. The Student's t‐test was used to compare the difference in the mean of quantitative variables. Qualitative variables were presented by percentage. The univariable and multivariable (logistic regression) was conducted to evaluate the association between multiple factors (age, gender, vaccination status, and Omicron variants) and clinical outcomes (hospitalization and death) of COVID‐19 patients. We did not carry out an analysis of transfer to intensive care unit outcomes because of low effectiveness. The results were presented by odds ratio with a 95% confidence interval. p < 0.05 was considered statistically significant.