Different effects of vaccine on VST in critical and non-critical COVID-19 patients: A retrospective study of 363 cases

AIM: To explore the risk factors of prolonged viral shedding time (VST) in critical/non-critical COVID-19 patients during hospitalization. METHODS: In this retrospective study, we enrolled 363 patients with SARS-CoV-2 infection admitted in a designated hospital during the COVID-19 outbreak in Nanjing Lukou International Airport. Patients were divided into critical (n = 54) and non-critical (n = 309) groups. We analyzed the relationship between the VST and demographics, clinical characteristics, medications, and vaccination histories, respectively. RESULTS: The median duration of VST was 24 d (IQR, 20–29) of all patients. The VST of critical cases was longer than non-critical cases (27 d, IQR, 22.0–30.0 vs. 23 d, IQR 20–28, P < 0.05). Cox proportional hazards model showed that ALT (HR = 1.610, 95%CI 1.186–2.184, P = 0.002) and EO% (HR = 1.276, 95%CI 1.042–1.563, P = 0.018) were independent factors of prolonged VST in total cases; HGB (HR = 0.343, 95%CI 0.162–0.728, P = 0.005) and ALP (HR = 0.358, 95%CI 0.133–0.968, P = 0.043) were independent factors of prolonged VST in critical cases, while EO% (HR = 1.251, 95%CI 1.015–1.541, P = 0.036) was the independent factor of prolonged VST in non-critical cases. Vaccinated critical cases showed higher levels of SARS-CoV-2-IgG (1.725 S/CO, IQR 0.3975–28.7925 vs 0.07 S/CO, IQR 0.05–0.16, P < 0.001) and longer VSTs (32.5 d, IQR 20.0–35.25 vs 23 d, IQR 18.0–30.0, P = 0.011) compared with unvaccinated critical patients. Fully vaccinated non-critical cases, however, presented higher levels of SARS-CoV-2-IgG (8.09 S/CO, IQR 1.6975–55.7825 vs 0.13 S/CO IQR 0.06–0.41, P < 0.001) and shorter VSTs (21 d, IQR 19.0–28.0 vs 24 d, IQR 21.0–28.5, P = 0.013) compared with unvaccinated non-critical patients. CONCLUSIONS: Our results suggested that risk factors of prolonged VST were different between critical and non-critical COVID-19 patients. Increased level of SARS-CoV-2-IgG and vaccination did not shorten the VST and hospital stay in critical COVID-19 patients.