Clinical and epidemiological factors causing longer SARS-CoV 2 viral shedding: the results from the CoviCamp cohort

The aim of this study was to investigate how long hospitalized patients stayed positive to the nasopharyngeal swab, and what demographic and clinical factors influence the time-to-negative swab.

We enrolled in a multicenter, observational, retrospective study involving 17 COVID-19 units in eight cities of the Campania, southern Italy all patients hospitalized from March 2020 to May 2021 diagnosed with Severe Acute Respiratory Distress Syndrome-Coronavirus-2 (SARS-CoV-2) infection for whom time-to-negative swab was available.

963 patients were enrolled. We defined three groups considering time-to-negative swab: the first including patients with time-to-negative swab before the 26th day, the second including patients with time-to-negative swab from day 26 to day 39, and the third including patients with time-to-negative swab > 39 days. 721 (74.9%) patients belonged to the first group, 194 (20.1%) to the second, and 52 (5.4%) belonged to the third group. Belonging to group 2 and 3 seemed to be influenced by age (p value < 0.001), Charlson comorbidity index (p = 0.009), arterial hypertension (p = 0.02), cardiovascular disease (p = 0.017), or chronic kidney disease (CKD) (p = 0.001). The multivariable analysis confers a leading role to CKD, with an odds ratio of 2.3 as factor influencing belonging to the groups showing a longer time-to-negative swab. Patients with CKD and diabetes were more frequently in the third group.

Our analysis showed that CKD is a factor related to longer time-to-negative swab, probably because of immunosuppression related to this condition.