Table 4.
Outcomes and risk assessment.
| Reference Number and First Author | Complications | Long COVID Risk (OR/RR/HR) | Other Risks (OR/RR/HR) |
|---|---|---|---|
| 1 [21] Al-Aly et al. | ICU admissions (2.4%) | 0.82 (0.80–0.85) | Mortality - 0.66 (0.58–0.74) |
| 2 [22] Antonelli et al. | Hospitalization in frail older adults post-first dose (23%) and post-second dose (6%) | 0.54 (0.36–0.80) | Frailty in older adults post-first dose (OR 1.93, 95% CI 1.50–2.48); Deprivation post-first dose (OR 1.11, 95% CI 1.01–1.23 for high deprivation) |
| 3 [23] Ayoubkhani et al. | Long COVID symptoms: 9.5% in double-vaccinated vs. 14.6% in unvaccinated; Activity-limiting symptoms: 5.5% in double-vaccinated vs. 8.7% in unvaccinated | 0.59 (0.50–0.69) | Activity-limiting symptoms: aOR 0.59 (95% CI, 0.48–0.73) |
| 4 [24] Azzolini et al. | Long COVID prevalence: Overall 31.0%, Wave 1: 48.1%, Wave 2: 35.9%, Wave 3: 16.5% | 0.29 (0.13–0.64) | Higher risk with older age (OR, 1.23), allergies (OR, 1.50), and more comorbidities (OR, 1.32) |
| 5 [25] Brannock et al. | NR | 0.70 (0.65–0.75) | Number of complications: 0.70 (0.60–0.81) |
| 6 [26] Ballouz et al. | Long-COVID: 25.3% after Wildtype infection, 17.2% after Delta infection, 13.1% after Omicron infection | 0.42 (0.24–0.68) | No clear pattern in long-COVID-related symptoms across variants; absolute risk reduction −10.6% |
| 7 [27] Emecen et al. | ICU admissions (52.0% at 1 month, 36.2% at 3 months, 28.3% at 6 months) | 0.53 (0.40–0.72) | ICU admission: 2.18 (1.51–3.14) |
| 8 [28] Ioannou et al. | Long-COVID (13.6%) | 0.78 (0.69–0.90) | Hospitalization (AOR 2.60: 2.51–2.69), mechanical ventilation (AOR 2.46: 2.26–2.69) |
| 9 [29] Meza-Torres et al. | ICU admissions (0.7%) | 0.74 (0.40–1.37) | OR 2.66 (CI 2.46–2.88) for community infection, OR 2.42 (CI 2.03–2.89) for hospital infection |
| 10 [30] Mohr et al. | NR | 0.70 (0.58–0.84) | Vaccinated patients returned to work sooner (HR 1.37, 1.04–1.79) |
| 11 [31] Taquet et al. | NR | 1.01 (0.96–1.05) | NR |
| 12 [32] van der Maaden et al. | NR | 0.90 (0.75–1.08) | Higher symptom prevalence in cases vs. controls (48.5% vs. 29.8% test-negative and 26.0% population) |
| 13 [33] Zisis et al. | NR | 0.42 (0.39–0.44) | Hypertension OR 0.33 (0.26–0.42), Respiratory symptoms OR 0.54 (0.50–0.57), Diarrhea and constipation OR 0.44 (0.40–0.49) |