Evaluation of the Rapid Antigen Detection Test for Diagnosing SARS-CoV-2 during the COVID-19 Pandemic: Experience from a Centralized Isolation Site in Shanghai, China.

Rapid and reliable diagnosis is important for the management of individuals infected with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The rapid antigen detection test (RADT) is a rapid, inexpensive, and easy method. Several studies have reported that RADTs performed well in many countries; however, very few studies have been reported in China. In this study, we assessed the performance of the RADT (Ediagnosis COVID-19 antigen test kit). This study was conducted in a centralized isolation site in Shanghai and enrolled 716 patients with COVID-19 and 203 noninfected participants. Nasopharyngeal swabs from all participants were collected on the same day and tested using the RADT and real-time reverse transcription-PCR (RT-PCR). The performance of the RADT was evaluated in different scenarios, such as threshold cycle (CT) values, symptomatic phase, and symptoms on the day of testing. The results demonstrated that the sensitivity for patients with CT values lower than 20 was 96.55% (95% confidence interval [CI], 87.05 to 99.4). The sensitivities were 78.4% (95% CI, 69.96 to 85.05) for participants within 5 days after the first RT-PCR-positive result and 90.77% (95% CI, 80.34 to 96.19) within 5 days after symptom onset. Moreover, the sensitivity of the RADT was more than 80% for patients with symptoms on the day of testing, including fever (89.29%), cough (86.84%), stuffy nose (92.59%), runny nose (92%), sore throat (81.25%), and muscle pain (80.77%), especially for those with upper respiratory tract symptoms. The specificity of the RADT was good in all scenarios. During the SARS-CoV-2 epidemic, Ediagnosis performed excellently in individuals with a higher viral load (evidenced by lower CT values), individuals in the early symptomatic phase, and especially those with upper respiratory tract symptoms. IMPORTANCE RADTs have demonstrated excellent performance in many counties for screening SARS-CoV-2 infection, but very few studies have been conducted in China. The performance of RADTs is largely related to different real-life scenarios. In our study, the performance of the RADT was evaluated in different scenarios, such as CT values, symptomatic phase, and symptoms on the day of testing. The results demonstrated that Ediagnosis (an RADT made in China) performed excellently for individuals with a higher viral load (evidenced by lower CT values), individuals in the early symptomatic phase, and especially those with upper respiratory tract symptoms.

Hydroxychloroquine treatment on SARS-CoV-2 receptor ACE2, TMPRSS2 and NRP1 expression in human primary pterygium and conjunctival cells.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the pathogen for coronavirus disease 2019 (COVID-19) pandemic. Its infection depends on the binding of spike protein to the host cell receptor angiotensin-converting enzyme 2 (ACE2), type II transmembrane serine protease (TMPRSS2) and neuropilin-1 (NRP1). Hydroxychloroquine has been applied as one of the COVID-19 treatment strategies. Here we aimed to evaluate hydroxychloroquine treatment on SARS-CoV-2 receptor expression in human primary pterygium and conjunctival cells and its potential influences. Expression of ACE2, TMPRSS2 and NRP1 proteins were found in the epithelial layer of both primary pterygium and conjunctiva tissues as well as in their isolated fibroblasts. High concentration of hydroxychloroquine treatment significantly reduced the viability of both primary pterygium and conjunctival cells. ACE2 protein expression was significantly decreased in both pterygium and conjunctival cells after hydroxychloroquine treatment. Hydroxychloroquine also reduced NRP1 protein expression in conjunctival cells. In contrast, TMPRSS2 protein expression showed slightly increased in conjunctival cells. Notably, ROS production and SOD2 expression was significantly elevated in both pterygium and conjunctival cells after hydroxychloroquine treatment. In summary, this study revealed the reduction of ACE2 and NRP1 expression by hydroxychloroquine in human primary pterygium and conjunctival fibroblasts; yet with the increase in TMPRSS2 expression and oxidative stress and decrease in cell viability. Implementation of hydroxychloroquine for COVID-19 treatment should be carefully considered with its potential side effects and in combination with TMPRSS2 inhibitor.

Are They Just Two Children COVID-19 Cases Confused With Flu?

COVID-19, an emerging infectious disease, has quickly spread all over the world. All human populations are susceptible to this disease. Here we present two pediatric COVID-19 cases, both of whom exhibited negative SARS-CoV-2 nucleic acid tests upon nasopharyngeal swab and were initially diagnosed with influenza A infection. COVID-19 was later confirmed in both patients by serum antibodies of SARS-CoV-2 and nucleic acid test on stool samples. Because children are susceptible to many respiratory pathogens, especially influenza, we concluded that children can be coinfected with multiple pathogens, and more attention should be paid to the exploration of SARS-CoV-2 during the pandemic of COVID-19. This report shows the possibility of misdiagnosis or missed diagnosis of children with COVID-19. We suggest that highly suspected pediatric COVID-19 cases with negative nucleic acid tests on nasopharyngeal swabs should be further checked by performing a nucleic acid test on stool samples and testing serum for antibodies against SARS-CoV-2.

Expression of SARS-CoV-2 receptor ACE2 and TMPRSS2 in human primary conjunctival and pterygium cell lines and in mouse cornea.

PURPOSE: To determine the expressions of SARS-CoV-2 receptor angiotensin-converting enzyme 2 (ACE2) and type II transmembrane serine protease (TMPRSS2) genes in human and mouse ocular cells and comparison to other tissue cells. METHODS: Human conjunctiva and primary pterygium tissues were collected from pterygium patients who underwent surgery. The expression of ACE2 and TMPRSS2 genes was determined in human primary conjunctival and pterygium cells, human ocular and other tissue cell lines, mesenchymal stem cells as well as mouse ocular and other tissues by reverse transcription-polymerase chain reaction (RT-PCR) and SYBR green PCR. RESULTS: RT-PCR analysis showed consistent expression by 2 ACE2 gene primers in 2 out of 3 human conjunctival cells and pterygium cell lines. Expression by 2 TMPRSS2 gene primers could only be found in 1 out of 3 pterygium cell lines, but not in any conjunctival cells. Compared with the lung A549 cells, similar expression was noted in conjunctival and pterygium cells. In addition, mouse cornea had comparable expression of Tmprss2 gene and lower but prominent Ace2 gene expression compared with the lung tissue. CONCLUSION: Considering the necessity of both ACE2 and TMPRSS2 for SARS-CoV-2 infection, our results suggest that conjunctiva would be less likely to be infected by SARS-CoV-2, whereas pterygium possesses some possibility of SARS-CoV-2 infection. With high and consistent expression of Ace2 and Tmprss2 in cornea, cornea rather than conjunctiva has higher potential to be infected by SARS-CoV-2. Precaution is necessary to prevent possible SARS-CoV-2 infection through ocular surface in clinical practice.