Cellular immunity reflects the persistent symptoms among COVID-19 recovered patients in Japan (preprint)

Coronavirus disease (COVID-19) often causes persistent symptoms long after infection, referred to as "long COVID" or post-acute COVID-19 syndrome (PACS). This phenomenon has been studied primarily concerning B-cell immunity, while the involvement of T-cell immunity is still unclear. This retrospective study aimed to examine the relationship among the number of symptoms, cytokine levels, and the (Enzyme-linked immunosorbent spot) ELISPOT assay data in patients with COVID-19. To examine inflammatory conditions, plasma interleukin (IL)-6, IL-10, IL-18, chemokine ligand 9 (CXCL9), chemokine ligand 3 (CCL3), and vascular endothelial growth factor (VEGF) levels were analyzed using plasma obtained from COVID-19 recovery patients and healthy controls (HC). These levels were significantly higher in the COVID-19 group than those in the HC group. ELISPOT assays were performed to investigate the correlation between COVID-19 persistent symptoms and T-cell immunity. Cluster analysis of ELISPOT categorized COVID-19 recovery patients in the ELISPOT-high and -low groups, based on the values of S1, S2, and N. The number of persistent symptoms was significantly higher in the ELISPOT-low group than those in the ELISPOT-high group. Thus, T cell immunity is critical for the rapid elimination of COVID-19 persistent symptoms, and its measurement immediately after COVID-19 recovery might predict long-term COVID-19 or PACS.

Diligent medical activities of a publicly designated medical institution for infectious diseases pave the way for overcoming COVID-19: A positive message to people working at the cutting edge (preprint)

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), which causes coronavirus disease 2019 (COVID-19), is highly infectious and has spread worldwide. An important factor compounding spread is the infection of medical staff with SARS-CoV-2, which threatens the collapse of the very institutions required to treat COVID-19. The possibility of virus transmission from patients with COVID-19 to medical staff is thus of primary concern. Asymptomatic COVID-19 carriage among hospital staff could also be conceivable to act as a potent source of ongoing transmission. Here we show that, surprisingly, none of the medical staff working at a hospital with COVID-19 patients had IgG antibodies for SARS-CoV-2, indicating that virus transmission from patients to medical staff did not occur in these medical workers. These results show that standard preventive measures against infectious diseases can prevent SARS-CoV-2 exposure in medical staff, and should greatly encourage medical practitioners at the front line of this pandemic.