Research letter that may be of interest to those who want to know how vaccination may affect the risk of long COVID:
Out of 2,560 routinely tested health care personnel at 9 health care facilities in Italy, 739 had COVID-19 (89 asymptomatic). All received 2 doses of Pfizer vaccine in January - February 2021 and a Pfizer booster in November - December 2021.
| # vaccine doses before infection | % with long COVID | # with long COVID | # without long COVID |
|---|---|---|---|
| 0 | 41.8 | 176 | 245 |
| 1 | 30.0 | 3 | 7 |
| 2 | 17.4 | 8 | 38 |
| 3 | 16.0 | 42 | 220 |
Some odds ratios of long COVID compared to female, mean age, no allergies or comorbidities, no vaccine doses:
| Characteristic | OR (95% CI) | P-value |
|---|---|---|
| Male | 0.65 (0.44-0.98) | 0.04 |
| Age (> mean+11.3 years) | 1.23 (1.01-1.49) | 0.04 |
| Allergies | 1.50 (1.06-2.11) | 0.02 |
| Comorbidities | 1.32 (1.04-1.68) | 0.03 |
| 2 doses vaccine | 0.25 (0.07-0.87) | 0.03 |
| 3 doses vaccine | 0.16 (0.03-0.84) | 0.03 |