Prolonged Viral Shedding in Cancer Patients with Asymptomatic or Mild Omicron Infection: A Retrospective Study

Background: This study aimed to investigate the risk factors for persistent viral shedding in cancer patients after Omicron infection. Methods: Patients with asymptomatic or mild Omicron infection (218 years) who were treated in a makeshift hospital in Shanghai were enrolled from 9 Apr to 11 May, 2022. Deidentified information of all patients were collected retrospectively. Logistic regression model was used to identify risk factors associated with prolonged duration of viral shedding (defined as the time from the day of first positive SARS-CoV-2 RNA test to the first day of two consecutive negative SARS-CoV-2 RNA tests). Results: A total of 1442 Omicron-infected patients were enrolled, including 129 cancer patients and 1313 non-cancer patients. The baseline clinical characteristics of cancer and non-cancer patients were balanced by propensity score matching (1:4). Compared with non-cancer patients, a higher odds ratio ([OR] 1.84, 95% CI 1.24-2.76, P = 0.003) of lasting viral shedding for 27 days was found in cancer patients. Further subgroup analyses found that cancer patients were at higher risk for prolonged viral shedding in a subgroup of patients without hypertension (OR 1.89), diabetes (OR 1.80), or other chronic disease (OR 2.13), unvaccinated (OR 1.97), and asymptomatic (OR 2.36). In addition, 29 patients with active cancer and 19 patients with inactive cancer were identified. The median duration of viral shedding in the active cancer group was longer than that in the inactive cancer group (10 vs 6 days, P = 0.002). The risk of persistent viral shedding 27 days was also increased in the active cancer group (OR 5.33, 95% CI 1.49-21.51, P = 0.013). Conclusion: Cancer disease is an independent risk factor for prolonged viral shedding in Omicron infected patients, especially in patients with active cancer.