Issue Editor: Zheng-Li Shi, PhD, Wuhan Institute of Virology, Chinese Academy of Sciences
By the end of November 2020, SARS-CoV-2—the new coronavirus behind the disease COVID-19—has infected over 60 million people around the world and caused about one and a half million deaths. Facing the biggest global pandemic of the century, doctors, scientists and the scientific community have been working hard to uncover the pathogenesis and search for effective scientific solutions. Virologica Sinica has online published a series of original articles and reviews on SARS-CoV-2 and COVID-19, covering topics on clinical cohorts/cases and disease features, virus characterization and surveillance, diagnosis and improved methods, antiviral agents and therapeutic treatment, and etc, and they are collectively presented in this special issue. Those researches have greatly advanced our understandings of and empowered our strength to combat the disease. The cover depicts the SARS-CoV-2 virus particle, surrounded by human blood cells.
Coronavirus disease 2019 (COVID-19) is a viral infection caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). From March 2020, several studies indicate that many subjects affected by mild-to-moderate COVID-19 presented olfactory/gustatory dysfunction (OD/GD) that appeared strongly correlated between them but not with the other symptoms suggestive of upper airway infectionIn order to evaluate patterns of gustatoy recovery, data from patients with confirmed COVID-19 were collected prospectively from 4 University Hospitals. At this relatively early point in the pandemic, the authors considered that subjective patterns of recovery of olfactory disfunction in COVID-19 patients are valuable for our patients, for hypothesis generation and treatment development.
We reported recently that hypertension is a risk factor for severe cases of COVID-19, independent of age and other variables (Liu et al. 2020a). An important question is why patients with hypertension and diabetes yield poorer clinical outcomes than those without. Human pathogenic coronavirus SARS-CoV-2 utilizes angiotensin-converting enzyme 2 (ACE2) as a receptor for viral cell entry. Since the levels of ACE2 are substantially increased in patients with hypertension or diabetes, who are treated with ACE inhibitors (ACEIs) and angiotensin Ⅱ type-Ⅰ receptor blockers (ARBs) (Ferrario et al. 2005), Fang and colleagues hypothesized that ACE2-stimulating drugs could potentially increase the risk of developing severe COVID-19 (Fang et al. 2020). This was not supported by a recent study led by Dr. Reynolds (Reynolds et al. 2020), whose analysis showed no positive association for ACEIs or ARBs for either the risk of SARS-CoV-2 infection or severe illness (Reynolds et al. 2020). What else might explain the poorer clinical outcomes of COVID-19 patients with hypertension or diabetes?To explore this question, we re-analysed the same cohort of 99 COVID-19 patients discharged from the general wards of Renmin Hospital of Wuhan University between 5 February 2020 and 14 March 2020 (Ethics approval No: WDRY2020-K124) (Liu et al. 2020a, b).
Sub-Saharan countries are sadly linked with similar poor indicators, such as high poverty and mortality rates, the burden of disease, fragile health systems and poorly developed infrastructure. Along with the rest of the world, Sub-Saharan countries are facing this new coronavirus outbreak. Nevertheless, chaotic predictions of a particularly destructive epidemic in Africa do not seem to be borne out, at least for the time being. But uncertainties remain, such as how the virus is spreading in countries with low incomes, informal economies, high HIV/tuberculosis prevalence, extremely low median age, or warm/dry climates and for which containments are almost impossible to enforce? Not even 8 months after the first reported case in China, parts of the world are already showing post-lockdown twilight measures. Yet, the war is certainly far from over, because the virus is gaining ground in the sub-Saharan zone. This viewpoint attempts to describe the COVID-19 crisis in a sub-Saharan perspective, in particular in the Republic of Chad, from both, distant perception and by living it on a daily basis.
Reverse transcription-polymerase chain reaction (RT-PCR) is an essential method for specific diagnosis of SARS-CoV-2 infection. Unfortunately, false negative test results are often reported. In this study, we attempted to determine the principal causes leading to false negative results of RT-PCR detection of SARS-CoV-2 RNAs in respiratory tract specimens. Multiple sputum and throat swab specimens from 161 confirmed COVID-19 patients were tested with a commercial fluorescent RT-PCR kit targeting the ORF1ab and N regions of SARS-CoV-2 genome. The RNA level of a cellular housekeeping gene ribonuclease P/MRP subunit p30 (RPP30) in these specimens was also assessed by RT-PCR. Data for a total of 1052 samples were retrospectively re-analyzed and a strong association between positive results in SARS-CoV-2 RNA tests and high level of RPP30 RNA in respiratory tract specimens was revealed. By using the ROC-AUC analysis, we identified Ct cutoff values for RPP30 RT-PCR which predicted false negative results for SARS-CoV-2 RT-PCR with high sensitivity (95.03%–95.26%) and specificity (83.72%–98.55%) for respective combination of specimen type and amplification reaction. Using these Ct cutoff values, false negative results could be reliably identified. Therefore, the presence of cellular materials, likely infected host cells, are essential for correct SARS-CoV-2 RNA detection by RT-PCR in patient specimens. RPP30 could serve as an indicator for cellular content, or a surrogate indicator for specimen quality. In addition, our results demonstrated that false negativity accounted for a vast majority of contradicting results in SARS-CoV-2 RNA test by RT-PCR.
The coronavirus disease 2019 (COVID-19), caused by SARS-CoV-2, has spread around the world with high mortality. To diagnose promptly and accurately is the vital step to effectively control its pandemic. Dynamic characteristics of SARS-CoV-2-specific antibodies which are important for diagnosis of infection have not been fully demonstrated. In this retrospective, single-center, observational study, we enrolled the initial 131 confirmed cases of COVID-19 at Jin-Yin-Tan Hospital who had at least one-time antibody tested during their hospitalization. The dynamic changes of IgM and IgG antibodies to SARS-CoV-2 nucleocapsid protein in 226 serum samples were detected by ELISA. The sensitivities of IgM and IgG ELISA detection were analyzed. Result showed that the sensitivity of the IgG ELISA detection (92.5%) was significantly higher than that of the IgM (70.8%) (P < 0.001). The meantimes of seroconversion for IgM and IgG were 6 days and 3 days, respectively. The IgM and IgG antibody levels peaked at around 18 days and 23 days, and then IgM fell to below the baseline level at about day 36, whereas IgG maintained at a relatively high level. In conclusion, antibodies should be detected to aid in diagnosis of COVID-19 infection. IgG could be a sensitive indicator for retrospective diagnosis and contact tracing, while IgM could be an indicator of early infection.