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Introduction: based on the report of a cluster of pneumonia cases of unknown etiology on December 31, 2019 in Wuhan, China, the World Health Organization declared the outbreak to be a public health emergency of international concern; COVID-19 became a pandemic. The process of collecting the sample in the detection of SARS-CoV-2 represents one of the initial and highly relevant stages for carrying out an efficient and robust diagnosis. Objective: to characterize aspects related to the detection of SARS-CoV-2 and the taking of samples in the Province of Villa Clara. Methods: a descriptive, observational, retrospective investigation was carried out with the objective of characterizing aspects related to the detection of SARS-CoV-2 and the taking of samples in the Province of Villa Clara from the 157 confirmed cases with the disease in the period of study. Results: more than half of the cases were taken for bilateral nasal exudate, with a mean threshold cycle of 27.9, with a standard deviation of 7.1. 53.3% of the means of transport corresponded to the Sensure Biotech brand; this type of transport medium was the one with the most samples, with a threshold cycle below 20. Conclusions: the sample with the highest positivity was the bilateral nasal exudate, which coincides with international authors. Of the means of transport evaluated, Sensure Biotech was the one that offered the best results. In the case of asymptomatic patients, the sample that presented the best results was bilateral nasal exudate. [ABSTRACT FROM AUTHOR]

Background: Assessing the humoral immunity of patients with underlying diseases after being infected with SARS-CoV-2 is essential for adopting effective prevention and control strategies. The purpose of this study is to analyze the seroprevalence of people with underlying diseases and the dynamic change features of anti-SARS-CoV-2 antibodies. Methods: We selected 100 communities in Wuhan using the probability-proportional-to-size sampling method. From these 100 communities, we randomly selected households according to a list provided by the local government. Individuals who have lived in Wuhan for at least 14 days since December 2019 and were ≥ 40 years old were included. From April 9–13, 2020, community staff invited all selected individuals to the community healthcare center in batches by going door-to-door or telephone. All participants completed a standardized electronic questionnaire simultaneously. Finally, 5 ml of venous blood was collected from all participants. Blood samples were tested for the presence of pan-immunoglobulins, IgM, IgA, and IgG antibodies against SARS-CoV-2 nucleocapsid protein and neutralising antibodies were assessed. During the period June 11–13, 2020 and October 9–December 5, 2020, all family members of a positive family and matched negative families were followed up twice. Results: The seroprevalence of anti-SARS-CoV-2 antibodies in people with underlying diseases was 6.30% (95% CI [5.09–7.52]), and that of people without underlying diseases was 6.12% (95% CI [5.33–6.91]). A total of 313 people were positive for total antibodies at baseline, of which 97 had underlying disease. At the first follow-up, a total of 212 people were positive for total antibodies, of which 66 had underlying disease. At the second follow-up, a total of 238 people were positive for total antibodies, of which 68 had underlying disease. A total of 219 participants had three consecutive serum samples with positive total antibodies at baseline. The IgG titers decreased significantly with or without underlying diseases (P < 0.05) within the 9 months at least, while the neutralizing antibody titer remained stable. The titer of asymptomatic patients was lower than that of symptomatic patients (baseline, P = 0.032, second follow-up, P = 0.018) in the underlying diseases group. Conclusion: Our research focused on the serological changes of people with and without underlying diseases in a state of single natural infection. Regardless of the underlying diseases, the IgG titer decreased significantly over time, while there was no significant difference in the decline rate of IgG between with and without underlying diseases. Moreover, the neutralizing antibody titer remained relatively stable within the 9 months at least. [ABSTRACT FROM AUTHOR]

Objective: To examine the clinical characteristics of patients with asymptomatic novel coronavirus disease 2019 (COVID-19) and compare them with those of patients with mild disease. Design: A retrospective cohort study. Setting: Multiple medical centers in Wuhan, Hubei, China. Participants: A total of 3,263 patients with laboratory-confirmed severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) infection between February 4, 2020, and April 15, 2020. Main outcome measures: Patient demographic characteristics, medical history, vital signs, and laboratory and chest computed tomography (CT) findings. Results: A total of 3,173 and 90 patients with mild and moderate, and asymptomatic COVID-19, respectively, were included. A total of 575 (18.2%) symptomatic patients and 4 (4.4%) asymptomatic patients developed the severe illness. All asymptomatic patients recovered; no deaths were observed in this group. The median duration of viral shedding in asymptomatic patients was 17 (interquartile range, 9.25–25) days. Patients with higher levels of ultrasensitive C-reactive protein (odds ratio [OR] = 1.025, 95% confidence interval [CI], 1.01–1.04), lower red blood cell volume distribution width (OR = 0.68, 95% CI 0.51–0.88), lower creatine kinase Isoenzyme(0.94, 0.89–0.98) levels, or lower lesion ratio (OR = 0.01, 95% CI 0.00–0.33) at admission were more likely than their counterparts to have asymptomatic disease. Conclusions: Patients with younger ages and fewer comorbidities are more likely to be asymptomatic. Asymptomatic patients had similar laboratory characteristics and longer virus shedding time than symptomatic patients; screen and isolation during their infection were helpful to reduce the risk of SARS-CoV-2 transmission. [ABSTRACT FROM AUTHOR]