High titers of neutralizing antibodies in the blood fail to eliminate SARS‐CoV‐2 viral RNA in the upper respiratory tract

Abstract

Retest‐positive severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) viral RNA, as a unique phenomenon among discharged individuals, has been demonstrated to be safe in the community. Still, the underlying mechanism of viral lingering is less investigated. In this study, first, we find that the frequency of viral RNA‐positive retesting differs among variants. Higher ratios of viral RNA‐positive retest were more frequently observed among Delta (61.41%, 514 of 837 cases) and Omicron (39.53%, 119 of 301 cases) infections than among ancestral viral infection (7.27%, 21 of 289 cases). Second, the tissues where viral RNA reoccurred were altered. Delta RNA reoccurred mainly in the upper respiratory tract (90%), but ancestral virus RNA reoccurred mainly in the gastrointestinal tract (71%). Third, vaccination did not reduce the frequency of viral RNA‐positive retests, despite high concentrations of viral‐specific antibodies in the blood. Finally, 37 of 55 (67.27%) Delta‐infected patients receiving neutralizing antibody therapy become viral RNA retest positive when high concentrations of neutralizing antibodies still patrol in the blood. Altogether, our findings suggest that the presentence of high titers of neutralizing antibodies in the blood is incompetent in clearing residual viral RNA in the upper respiratory tract.

Immune response and severity of Omicron BA.5 reinfection among individuals previously infected with different SARS-CoV-2 variants

“…All cases included in this study were local COVID-19 patients in Guangzhou as previously reported (Wang et al, 2021;Li et al, 2022;Li et al, 2023). The virus strains they were initially infected with were identified by whole viral genome sequencing.…”

“…During the COVID-19 pandemic period, patients infected with various virus strains in Guangzhou were admitted to the Guangzhou Eighth People's Hospital, Guangzhou Medical University, China. The ancestral strain was first reported on January 20, 2020, and the Delta and Omicron BA.2 variants primarily emerged on May 21, 2021 and April 8, 2022, respectively (Wang et al, 2020;Wang et al, 2021;Li et al, 2023). Some of these cases reinfected with the Omicron BA.5 variant between December, 2022 and January, 2023 according to the telephone questionnaires (Figure 1A).…”