Table 3. Multivariable Poisson Regression Models Considering Reporting Symptoms on the Survey as the Outcome, Including Only Participants Who Were Unvaccinated at Time of Symptom Onset With Surveys Filled Out Around the Specified Time Points.
| Variable | Time pointa | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| 1 Month (n = 537) | 3 Months (n = 602) | 6 Months (n = 836) | 9 Months (n = 848) | 12 Months (n = 913) | ||||||
| RR (95% CI) | P value | RR (95% CI) | P value | RR (95% CI) | P value | RR (95% CI) | P value | RR (95% CI) | P value | |
| Vaccinated after infection, survey filled out >14 d after vaccination | 0.68 (0.34-1.36) | .27 | 0.60 (0.35-1.05) | .08 | 0.59 (0.40-0.89) | .01 | 0.73 (0.46-1.17) | .19 | 0.68 (0.40-1.15) | .15 |
| Delta variant periodb | 0.96 (0.49-1.86) | .89 | 0.88 (0.42-1.81) | .72 | 0.87 (0.43-1.73) | .68 | 0.43 (0.16-1.18) | .10 | 0.45 (0.14-1.45) | .18 |
| Maximum symptom severity during acute illness | ||||||||||
| None or mild | 1 [Reference] | NA | 1 [Reference] | NA | 1 [Reference] | NA | 1 [Reference] | NA | 1 [Reference] | |
| Moderate | 2.50 (1.44-4.35) | .001 | 1.55 (0.77-3.09) | .22 | 1.93 (1.11-3.34) | .02 | 1.90 (1.04-3.48) | .04 | 2.12 (1.16-3.88) | .01 |
| Severe or critical | 1.95 (1.10-3.45) | .02 | 2.62 (1.33-5.17) | .01 | 2.51 (1.42-4.43) | .002 | 2.72 (1.49-4.95) | .001 | 3.15 (1.73-5.74) | <.001 |
| Age group, y | ||||||||||
| 18-44 | 1 [Reference] | NA | 1 [Reference] | NA | 1 [Reference] | NA | 1 [Reference] | NA | 1 [Reference] | NA |
| 45-64 | 1.65 (1.09-2.49) | .02 | 0.77 (0.41-1.45) | .42 | 0.98 (0.63-1.54) | .93 | 0.86 (0.53-1.41) | .56 | 0.88 (0.54-1.43) | .61 |
| ≥65 | 1.51 (0.80-2.86) | .20 | 1.84 (0.85-3.99) | .12 | 1.53 (0.78-3.03) | .22 | 1.21 (0.57-2.57) | .62 | 1.71 (0.88-3.33) | .11 |
| Sex | ||||||||||
| Female | 1.35 (0.92-1.98) | .13 | 1.37 (0.84-2.25) | .21 | 1.54 (1.03-2.30) | .03 | 1.16 (0.75-1.79) | .50 | 1.25 (0.81-1.93) | .30 |
| Male | 1 [Reference] | NA | 1 [Reference] | NA | 1 [Reference] | NA | 1 [Reference] | NA | 1 [Reference] | NA |
| BMI categoryc | ||||||||||
| Underweight or normal weight | 1 [Reference] | NA | 1 [Reference] | NA | 1 [Reference] | NA | 1 [Reference] | NA | 1 [Reference] | NA |
| Overweight | 1.05 (0.59-1.87) | .86 | 1.33 (0.64-2.79) | .45 | 1.50 (0.81-2.79) | .20 | 1.03 (0.57-1.89) | .91 | 2.16 (1.04-4.51) | .04 |
| Obesity | 1.05 (0.57-1.94) | .87 | 1.37 (0.61-3.06) | .45 | 1.57 (0.82-3.01) | .18 | 0.93 (0.48-1.82) | .84 | 1.87 (0.86-4.07) | .11 |
| Severe obesity | 1.48 (0.81-2.71) | .20 | 1.46 (0.61-3.50) | .40 | 1.87 (0.94-3.72) | .07 | 1.31 (0.64-2.66) | .46 | 2.15 (0.95-4.88) | .07 |
Abbreviations: BMI, body mass index (calculated as weight in kilograms divided by height in meters squared); NA, not applicable; RR, risk ratio.
a
Time after symptom onset (or date of first positive SARS-CoV-2 test result if symptom onset date was not available): 1 month, 14 to 44 days; 3 months, 45 to 134 days; 6 months, 135 to 224 days; 9 months, 225 to 314 days; and 12 months, 315 to 404 days.
b
July 1 to December 31, 2021.
c
Underweight or normal weight was defined as less than 25; overweight, 25 to 29; obesity, 30 to 34; and severe obesity, 35 or higher.