How fast and how well the Omicron epidemic was curtailed. A Guangzhou experience to share.

Introduction: SARS-CoV-2 has ravaged the world and undergone multiple mutations during the course of the COVID-19 pandemic. On 7 April 2022, an epidemic caused by SARS-CoV-2 Omicron (BA.2) variant broke out in Guangzhou, China, one of the largest transportation and logistical hubs of the country. Methods: To fast curtained the Omicron epidemic, based on the routine surveillance on the risk population of SARS-CoV-2 infection, we identify key places of the epidemic and implement enhanced control measures against Omicron. Results: Transmission characteristics of the Omicron variant were analyzed for 273 confirmed cases, and key places involved in this epidemic were fully presented. The median incubation time and the generation time were 3 days, and the reproduction number Rt was sharply increased with a peak of 4.20 within 2 days. We tried an all-out effort to tackle the epidemic in key places, and the proportion of confirmed cases increased from 61.17% at Stage 2 to 88.89% at Stage 4. Through delimited risk area management, 99 cases were found, and the cases were isolated in advance for 2.61 ± 2.76 days in a lockdown zone, 0.44 ± 1.08 days in a controlled zone, and 0.27 ± 0.62 days in a precautionary zone. People assigned with yellow code accounted for 30.32% (84/277) of confirmed COVID-19 cases, and 83.33% of them were detected positive over 3 days since code assignment. For the districts outside the epicenter, the implementation duration of NPIs was much shorter compared with the Delta epidemic last year. Conclusion: By blocking out transmission risks and adjusting measures to local epidemic conditions through the all-out effort to tackle the epidemic in key places, by delimiting risk area management, and by conducting health code management of the at-risk population, the Omicron epidemic could be contained quickly.

Coronavirus disease-2019 (COVID-19) infection in a 3-month-old infant: Clinical features, treatment and probable route of transmission.

This study aims to explore the clinical and epidemiological characteristics of infant patients with coronavirus disease-2019 (COVID-19) infection. Clinical and epidemiological data of a 3-month-old patient with COVID-19 were collected, including general status, clinical results, laboratory tests, imaging characteristics, and epidemiological reports. The infant had no fever but had mild respiratory symptoms. The major laboratory results included normal white blood cell counts and lymphocytopenia, notably with elevated interleukin (IL-)-17A, IL-17F, and tumor necrosis factor (TNF-)-α. The main manifestation of his chest computed tomography scan was pulmonary patchy shadows. All throat swabs and urine of the infant detected via Real-time Quantitative Polymerase Chain Reaction (RT-PCR) were negative, but his anal swab continued to test positive up to 40 days after onset of illness. Our study indicated that infants infected with COVID-19 may have relatively mild symptoms or clinical signs, IL-17A, IL-17 F, and TNF-α could be involved in the immune response of COVID-19. In addition, severe acute respiratory syndrome coronavirus 2(SARS-CoV-2) may shed through the gastrointestinal tract and convalescent carriers may exist among infant patients. We cannot rule out the possibility that infants may acquire infection from breastfeeding. Intensive care and nutrition support are recommended for infant patients with mild symptoms.

Down-regulation of miRNA-451a and miRNA-486-5p involved in benzene-induced inhibition on erythroid cell differentiation in vitro and in vivo.

Exposure to high-dose benzene leads to the inhibition of erythroid differentiation. However, whether lower doses of benzene exposure resemble high-dose effects in erythroid differentiation, as well as the underlying mechanisms, remains largely unknown. To identify the microRNAs (miRNAs) specifically responsible for benzene exposure and their regulatory role in erythroid differentiation, we performed miRNA microarray in CD34+ hematopoietic progenitor cells isolated from human umbilical cord blood after treatment with hydroquinone (HQ), a metabolite of benzene at concentrations of 0, 1.0, 2.5, and 5.0 µM. As a result, HQ treatment inhibited erythroid differentiation in a dose-response manner. miRNA microarray analysis revealed that miRNA-451a, miRNA-486-5p and miRNA-126-3p expression were significantly lower in HQ-treated CD34+ hematopoietic progenitor cells. In vitro studies showed that miRNA-451a and miRNA-486-5p were up-regulated during erythroid differentiation both in CD34+ hematopoietic progenitor cells and K562 cells. The increase in the percentage of benzidine-positive cells and the expression of γ-globin in K562 cells transfected with either miRNA-451a or miRNA-486-5p mimic indicated that both miRNAs played a role in the promotion of erythroid cell differentiation. Overexpression of either miRNA-451a or miRNA-486-5p attenuated the inhibitory effects on erythroid differentiation in HQ-treated K562 cells. In vivo study showed a decreasing count of peripheral red blood cell (RBC) in C57BL/6J male mice treated with aerosol benzene at concentrations of 0, 1, 5, 25 ppm (time weight average, TWA). In addition, the expression of miRNA-451a or miRNA-486-5p was negatively correlated with the concentration of benzene inhalation on erythroid toxicity of C57BL/6J mice. Particularly, the decline in miRNA-451a and miRNA-486-5p expression appeared in male chronic benzene poisoning patients, and was correlated with a constant decrease in their RBC counts over the first 3 months after being diagnosed. These findings indicate that the suppression of miRNA-451a or miRNA-486-5p might be associated with the benzene-induced perturbation of erythroid cell differentiation.