Universal admission screening for COVID-19 using quantitative antigen testing and questionnaire screening to prevent nosocomial spread.

BACKGROUND: In this study, we investigated diagnostic accuracy of quantitative severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antigen testing and whether universal screening was effective to prevent a nosocomial outbreak of coronavirus disease 2019 (COVID-19). METHODS: All adult patients admitted to an acute-care hospital in Tokyo, Japan, after receiving LUMIPULSE SARS-CoV-2 Ag using a nasopharyngeal swab and a brief questionnaire to evaluate symptoms and exposures from December 3, 2020 to March 20, 2021 were included. RESULTS: Of the 5191 patients, 53 were antigen-positive, 19 were inconclusive and 5119 were negative. The sensitivity and specificity (positive or inconclusive results) of the quantitative antigen test for COVID-19 diagnosis at admission was 0.957 (95% confidence interval [CI]: 0.855-0.995) and 0.995 (95% CI: 0.992-0.997), respectively. Six asymptomatic patients were identified on admission. Two patients were antigen-negative and diagnosed with COVID-19 later; however, they had been isolated prior to diagnosis because both had symptoms of COVID-19 and exposure. No nosocomial infections occurred during the period. CONCLUSION: Quantitative SARS-CoV-2 antigen testing was found to be valid for the early detection of asymptomatic COVID-19 patients as a universal screening test on admission.

Safety and Immunogenicity After a Three-Dose SARS-CoV-2 Vaccine Schedule in Allogeneic Stem Cell Transplant Recipients.

In allogeneic stem cell transplant (Allo-SCT) recipients, the cell-mediated and humoral immunogenicity of the 3-dose SARS-CoV-2 vaccination schedule has not been investigated in prospective studies. In a prospective cohort, we recruited 122 Allo-SCT recipients since August 2021, when Ontario began offering a 3-dose vaccine schedule for Allo-SCT recipients. We determined humoral and cell-mediated immunity and adverse effects of the 3-dose SARS-COV-2 vaccination schedule in Allo-SCT recipients. In immunogenicity analysis (n = 95), the median (interquartile range [IQR]) antibody titer against the receptor-binding domain (RBD) of the spike (S) protein after the third dose (10,358.0 U/mL [IQR = 673.9-31,753.0]) was significantly higher than that after the first (10.2 U/mL [IQR = 0.6-37.0]) and the second doses (125.6 U/mL [IQR = 2.8-1251.0]) (P < .0001). The haploidentical donor status was an independent risk factor (adjusted odds ratio = 7.67, 95% confidence interval [CI], 1.86-31.60) for suboptimal antibody response (anti-RBD < 100 U/mL). S-specific CD4+ and CD8+ T-cell responses were measured in a subset of Allo-SCT recipients (n = 20) by flow cytometry. Most developed antigen-specific CD4+ (55%-80%) and CD8+ T-cells (80%) after 2 doses of vaccine. Frequencies of CD4+ polyfunctional (P = .020) and IL-2 monofunctional (P = .013) T-cells significantly increased after the third dose. Twenty-three episodes (23/301 doses [7.6%]) of new-onset or worsening pre-existing graft-versus-host disease (GVHD) occurred, including 4 episodes after the third dose. We observed 4 relapses (3.27%). Seven patients developed SARS-CoV-2 infection despite vaccination, although none required hospitalization. In conclusion, the 3-dose SARS-CoV-2 vaccine schedule provided immunity associated with a low risk of GVHD and other adverse effects. This prospective cohort showed that the third dose of SARS-CoV-2 vaccine in allogeneic stem cell transplant recipients promoted better humoral and cellar immune responses than after the initial series without increasing the risk of GVHD or severe adverse effects.

Reverse Transcription Loop-Mediated Isothermal Amplification Assay-Based Infection Control Strategies for COVID-19 in a Hospital Under the State of Emergency in Tokyo, Japan in Spring 2020.

Studies describing reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay-based infection control strategies (LAMP-based ICSs) for coronavirus disease 2019 (COVID-19) are limited. We reviewed the medical records of cases in which RT-LAMP was performed. Standard ICSs and LAMP-based ICSs were implemented during the study period. The strategies were intended to impose longer periods of infection control precautions (ICPs) for specific patients, such as those with a history of exposure to COVID-19 patients and/or bilateral ground glass opacities (bGGO) on chest computed tomography (CT). Of 212 patients, which included 13 confirmed COVID-19 patients in the diagnostic cohort, exposure to COVID-19 patients (P <0.0001) and chest CT bGGO (P = 0.0022) were identified as significant predictors of COVID-19. In the 173 hospitalized patients in which the results of the first RT-LAMP were negative, the duration of ICPs was significantly longer in patients with exposure to COVID-19 and/or a high clinical index of suspicion and patients with bGGO than in the remaining patients (P = 0.00046 and P = 0.0067, respectively). Additionally, no confirmed COVID-19 cases indicating nosocomial spread occurred during the study period. Establishing a comprehensive system that combines rational LAMP-based ICSs with standard ICSs might be useful for preventing nosocomial spread.

[Current Status and Issues of COVID-19 in Japan]

Summary COVID-19 is an infectious disease that has spread throughout the world in a short period of time and is transmitted through droplet to droplet contact. COVID-19 is transmitted by close contact between people through droplets, and it is difficult to distinguish from other respiratory tract infections, such as influenza, because it has no specific symptoms. In Japan, a total of 76,118 test-positive cases have been reported since the first case was reported until September 16, 2020, indicating that the infection is spreading mainly in populated urban areas. As the influenza pandemic season approaches, it will be important to monitor the prevalence of COVID-19, which has symptoms similar to those of COVID-19.