Nearly one-fifth of unvaccinated people who contracted SARS-CoV-2 had post-COVID-19 symptoms up to 2 years after infection, a study shows. “Effective interventions are needed to reduce the burden of post-covid-19 condition,” the authors conclude. “Use of multiple outcome measures and consideration of the expected rates of recovery and heterogeneity in symptom trajectories are important in the design and interpretation of clinical trials.
In a canton of Zurich, Switzerland, 1,106 people with confirmed SARS-CoV-2 infection who were not vaccinated before infection were compared in a longitudinal cohort population study with 628 adults who did not have an infection. The main outcome measures were trajectories of self-reported health status and COVID-19–related symptoms at months 6, 12, 18, and 24 after infection and excess risk of symptoms at 6 months after infection compared with individuals who had no infection.
“22.9% (95% confidence interval 20.4% to 25.6%) of individuals infected with SARS-CoV-2 did not fully recover by six months,” the authors write. “The proportion of individuals who had an infection who reported not having recovered decreased to 18.5% (16.2% to 21.1%) at 12 months and 17.2% (14.0% to 20.8%) at 24 months after infection. When assessing changes in self-reported health status, most participants had continued recovery (68.4% (63.8% to 72.6%)) or had an overall improvement (13.5% (10.6% to 17.2%)) over time. Yet, 5.2% (3.5% to 7.7%) had a worsening in health status and 4.4% (2.9% to 6.7%) had alternating periods of recovery and health impairment.… Symptom prevalence was higher among individuals who were infected compared with those who were not at six months (adjusted risk difference 17.0% (11.5% to 22.4%)). Excess risk (adjusted risk difference) for individual symptoms among those infected ranged from 2% to 10%, with the highest excess risks observed for altered taste or smell (9.8% (7.7% to 11.8%)), post-exertional malaise (9.4% (6.1% to 12.7%)), fatigue (5.4% (1.2% to 9.5%)), dyspnoea (7.8% (5.2% to 10.4%)), and reduced concentration (8.3% (6.0% to 10.7%)) and memory (5.7% (3.5% to 7.9%)).”