A national network is essential for controlling this infection.

Background: Strict countermeasures for coronavirus disease (COVID-19) were undertaken in China without knowing their influence on asthma.Objective: To investigate the associations between the frequencies of asthma exacerbations and respiratory infections and air pollutants before and during the COVID-19 pandemic, which were direct consequences of countermeasures undertaken for the pandemic.Methods: Asthma exacerbations and respiratory infections among hospitalized children in the permanent population of Guangzhou City, China, from February to June 2016-2019 (before the pandemic) to February to June 2020 (during the pandemic) were collected in this cross-sectional study in Guangzhou.Results: The number of asthma exacerbation cases per month documented in the Guangzhou Women and Children's Hospital before (median: 13.5; range: 0-48) and during (median: 20; range: 0-34) the mitigative response to the COVID-19 pandemic was similar. The frequency of severe asthma exacerbation cases per month decreased, whereas that of mild asthma exacerbation cases per year increased (p = .004). The number of patients hospitalized with infectious respiratory diseases decreased from 146 (range: 90-172) per month before the pandemic to 42 (range: 33-57) per month during the pandemic (p = .004). Most pathogens and air pollutants decreased during the COVID-19 pandemic. The frequency of severe asthma exacerbations positively correlated to that of respiratory infections in children, but did not correlate to air pollutants. Conclusion:Strict countermeasures undertaken for the pandemic were associated with a decreased the frequency of infectious respiratory diseases and severe asthma exacerbations among urban children.

e16196 Background: Liver transplantation (LT) is one of the most effective therapeutic strategies for hepatocellular carcinoma (HCC), however, tumour recurrence after LT often leads to poor outcomes. At present, clinical characteristic profile, imaging diagnosis as well as level of serum biomarkers prior to LT could predict the prognosis in HCC patients treated by LT. However, the sensitivity and specificity of these biomarkers are limited, highlighting the crucial need to identify novel biomarkers. Previous clinical studies have shown that postoperative circulating tumor DNA (ctDNA) can be used as a predictive biomarker for the risk of recurrence in stage I-III solid tumor. This study aimed at investigating the relationship between the level of ctDNA and the probability of recurrence in HCC patients treated by LT. Methods: HCC patients receiving LT treatment were enrolled. Peripheral blood samples before LT and available matched tissue samples were collected. Targeted sequencing of 328 cancer-related genes were conducted. The clinicopathologic data of the patients was retrospectively analyzed. The predictive efficiency for recurrence after LT of different clinicopathologic parameters and ctDNA were accessed. Results: A total of 45 patients were enrolled, including 42 males (93%) and 3 females (7%), with a median age of 51 (range 31-76 years). Thirty-five patients (78%) had detectable ctDNA before LT while gene alterations were identified in tumor tissue of all the patients. Larger tumor size (> 5cm), cirrhosis, portal vein tumor thrombus (PVTT) and elevated AFP level (≥400ng/ml) prior to LT were associated with higher percentage of positive ctDNA (94% vs 73%, 84% vs 75%, 88% vs 79%, 88% vs 76%, respectively). Patients with micro-vessel invasion (MVI) had higher ctDNA abundance (maxVAF, P < 0.05). Interestingly, after over 3 years’ follow-up, clinical factors including MVI, PVTT, BCLC stage, maximum tumor diameter and serum AFP failed to predict disease free survival (DFS) and overall survival (OS). In contrast, the recurrence rate was remarkably augmented (48.6% vs 0%) and the median DFS was significantly decreased (390 days vs not reached, p< 0.05) in patients with detectable ctDNA. Conclusions: In conclusion, ctDNA could be a potential biomarker to sensitively predict the recurrence in patients with HCC treated by LT, which may help to improve the post-transplant management of these patients.

Background and ObjectivesSubstantial climate changes have led to the emergence and re-emergence of various infectious diseases worldwide, presenting an imperative need to explore the effects of meteorological factors on serious contagious disease incidences such as that of meningococcal meningitis (MCM).MethodsThe incidences of MCM and meteorology data between 1981 and 2010 were obtained from Chaoyang city. Structure Equation Modeling was used to analyze the relationships between meteorological factors and the incidence of MCM, using the LISREL software.ResultsThe SEM results showed that Adjusted Goodness of Fit Index (AGFI) = 0.30, Goodness of Fit Index (GFI) = 0.63, and Root Mean Square Error of Approximation (RMSEA) = 0.31. Humidity and temperature both had negative correlations with MCM incidence, with factor loads of −0.32 and −0.43, while sunshine was positively correlated with a factor load of 0.42. For specific observable variables, average air pressure, average evaporation, average air temperature, and average ground temperature exerted stronger influence, with item loads between observable variables and MCM incidence being −0.42, 0.34, −0.32, and −0.32 respectively.ConclusionPublic health institutions should pay more attention to the meteorological variables of humidity, sunshine, and temperature in prospective MCM control and prevention.

Background Ornithine transcarbamylase deficiency (OTCD) is a genetic metabolic disease. Its clinical manifestations are mainly central nervous system dysfunction caused by high blood ammonia. Late‐onset OTCD combined with central nervous system injury has a poor therapeutic response, which is one of the main factors affecting the prognosis and quality of life of patients. liver transplantation (LT) has gradually become a radical treatment for OTCD, which has achieved good results. However, there is no consensus on the timing of LT and problems of nervous system damage and repair. Methods We report the development of late‐onset OTCD with central nervous system injury in an 11‐year‐old child who received liver transplantation at our transplant center. His first symptoms were nonprojectile vomiting, followed by irritability and disturbance of consciousness, after which the disease progressed rapidly and finally resulted in a coma. After liver transplantation, the child's consciousness returned to normal, muscle strength of the limbs gradually recovered from grade 0 to grade 4, and muscle tone gradually recovered from grade 4 to grade 1, suggesting that the motor nerves had gradually recovered. However, the child is currently mentally retarded, and the language center has not yet fully recovered.At the same time, we made a literature review of OTCD. Conclusion For OTCD patients with central nervous system injury, liver transplantation can fundamentally solve the problem of ammonia metabolism in the liver and avoids further damage to the central nervous system caused by hyperammonemia. At the same time, children's nervous systems are in the developmental stage when neuroplasticity is greatest. If liver transplantation is performed as soon as possible, nerve repair is still possible.