Dynamics of viral load and anti-SARS-CoV-2 antibodies in patients with positive RT-PCR results after recovery from COVID-19

Abstract

Recently, the number of patients with coronavirus disease 2019 (COVID-19) who have tested positive for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), via the reverse transcription polymerase chain reaction (RT-PCR) test, after recovery has increased; this has caused a dilemma regarding the medical measures and policies. We evaluated the dynamics of viral load and anti-SARS-CoV-2 antibodies in four patients with positive RT-PCR results after recovery. In all patients, the highest levels of immunoglobulin G (IgG) and IgM antibodies were reached after about a month of the onset of the initial symptoms. Then, the IgG titers plateaued, and the IgM titers decreased, regardless of RT-PCR results. The IgG and IgM levels did not increase after the post-negative positive RT-PCR results in any of the patients. Our results reinforced that the post-negative positive RT-PCR results may be due to the detection of RNA particles rather than reinfection in individuals who have recovered from COVID-19.

Keywords: COVID-19; Reinfection; Severe acute respiratory syndrome coronavirus 2.

Figure 1

Viral kinetics and humoral immune response in four patients with repeat-positive reverse transcription polymerase chain reaction (RT-PCR) results for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) after recovering from COVID-19. (A) Patient 1: a 73-year-old woman; (B) Patient 2: a 33-year-old man; (C) Patient 3: a 31-year-old woman (the wife of Patient 2); and (D) Patient 4: an 18-month-old girl (the daughter of Patients 2 and 3). The gray lines represent the viral load levels; the solid blue lines represent the immunoglobulin G (IgG) trajectory; and the dashed blue lines represent the IgM trajectory. Solid grey triangles indicate that the specimen was an upper respiratory sample, and clear squares indicate that the specimen was a lower respiratory sample. RdRP, RNA-dependent RNA polymerase; Ct, cycle threshold.