Comparison of the duration of viral RNA shedding and anti-SARS-CoV-2 spike IgG and IgM antibody titers in COVID-19 patients who were vaccinated with inactivated vaccines or not: a retrospective study

BACKGROUND: At present, the role of inactivated vaccines in viral RNA shedding among Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) breakthrough infections is still unknown. METHODS: We collected data of 147 coronavirus disease 2019 (COVID-19) patients with mild-to-moderate illness who were hospitalized in the Third People’s Hospital of Yangzhou from 7 to 20 August 2021 and analyzed the differences in symptoms and laboratory tests among fully vaccinated (FV), partially vaccinated (PV) and unvaccinated (UV) patients. RESULTS: The median duration of viral RNA shedding was shorter in the FV (12 [IQR, 9.5–14] days) and PV (13 [IQR, 9–16.75] days) groups than in the UV group (15 [IQR, 11.75–17.25] days) (adjusted P < 0.001 and adjusted P = 0.23, respectively). The median titers of SARS-CoV-2-specific IgG and IgM were significantly higher in the FV (12.29 S/co [IQR, 2.08–63.59] and 0.3 S/co [IQR, 0.05–2.29], respectively) and PV (0.68 S/co [IQR, 0.14–28.69] and 0.12 S/co [0.03–5.23], respectively) groups than in the UV group (0.06 S/co [IQR, 0.03–0.47] and 0.04 S/co [IQR, 0.02–0.07]) (adjusted P < 0.001 and adjusted P = 0.008, respectively). CONCLUSIONS: Inactivated vaccines may shorten viral RNA shedding in breakthrough infected patients who have mild-to-moderate illness and may improve the ability of the host to generate specific antibodies to infection. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s12879-022-07808-2.