Estimating COVID-19 recovery time in a cohort of Italian healthcare workers who underwent surveillance swab testing

Benoni, Roberto; Campagna, Irene; Panunzi, Silvia; Varalta, Maria Silvia; Salandini, Giulia; De Mattia, Giulia; Turrina, Giuliano; Moretti, Francesca; Lo Cascio, Giuliana; Spiteri, Gianluca; Porru, Stefano; Tardivo, Stefano; Poli, Albino; Bovo, Chiara

Objectives The COVID-19 pandemic is putting a huge strain on the provision and continuity of care. The length of sickness absence of the healthcare workers as a result of SARS-CoV-2 infection plays a pivotal role in hospital staff management. Therefore, the aim of this study was to explore the timing of COVID-19 recovery and viral clearance, and its predictive factors, in a large sample of healthcare workers. Study design Retrospective cohort study. Methods The analysis was conducted on data collected during the hospital health surveillance programme for healthcare staff at the University Hospital of Verona; healthcare workers were tested for SARS-CoV-2 through RT-PCR with oro-nasopharyngeal swab samples. The health surveillance programme targeted healthcare workers who either had close contact with SARS-CoV-2 infected patients or were tested as part of the screening-based strategy implemented according to national and regional requirements. Recovery time was estimated from the first positive swab to two consecutive negative swabs, collected 24 hours apart, using survival analysis for both right-censored and interval-censored data. Cox proportional hazard was used for multivariate analysis. Results During the health surveillance programme, 6455 healthcare workers were tested for SARS-CoV-2 and 248 (3.8%, 95% confidence interval [CI] 3.4–4.3) reported positive results; among those who tested positive, 49% were asymptomatic, with a median age of 39.8 years, which is significantly younger than symptomatic healthcare workers (48.2 years, p < 0.001). Screening tests as part of the health surveillance programme identified 31 (12.5%) of the positive cases. Median recovery time was 24 days (95% CI 23–26) and 21.5 days (95% CI 15.5–30.5) in right- and interval-censoring analysis, respectively, with no association with age, sex or presence of symptoms. Overall, 63% of participants required >20 days to test negative on two consecutive swabs. Hospitalised healthcare workers (4.8%) were older and had a significantly longer recovery time compared with non-hospitalised healthcare workers in both analyses (33.5 vs 24 days, p = 0.005). Conclusions Recovery from COVID-19 and viral clearance may take a long time, especially in individuals who are hospitalised. To detect asymptomatic cases, screening programmes for healthcare workers is recommended.