[Analysis on infection sources and transmission chains of three outbreaks caused by 2019-nCoV Omicron variant in Beijing, China].

Objective: To investigate the infection sources and the transmission chains of three outbreaks caused by 2019-nCoV Omicron variant possibly spread through cross-border logistics in Beijing. Methods: Epidemiological investigation and big data were used to identify the exposure points of the cases. Close contacts were traced from the exposure points, and the cases' and environmental samples were collected for nucleic acid tests. Positive samples were analyzed by gene sequencing. Results: The Omicron variant causing 3 outbreaks in Beijing from January to April, 2022 belonged to BA.1, BA.1.1 and BA.2. The outbreaks lasted for 8, 12 and 8 days respectively, and 6, 42 and 32 cases infected with 2019-nCoV were reported respectively. International mail might be the infection source for 1 outbreak, and imported clothes might be the infection sources for another 2 outbreaks. The interval between the shipment start time of the imported goods and the infection time of the index case was 3-4 days. The mean incubation period (Q1, Q3) was 3 (2,4) days and the mean serial interval (Q1, Q3) was 3 (2,4)days. Conclusions: The 3 outbreaks highlighted the risk of infection by Omicron variant from international logistics-related imported goods at normal temperature. Omicron variant has stronger transmissibility, indicating that rapid epidemiological investigation and strict management are needed.

[Epidemiological characteristics of an epidemic of 2019-nCoV Omicron variant infection in Beijing].

Objective: To analyze the epidemiological characteristics and transmission chain of an epidemic of COVID-19 in Haidian district, Beijing. Methods: Descriptive epidemiological method was used to analyze the epidemiological characteristics of the epidemic, and field investigation and big data technology were used to analyze the transmission chain of the epidemic. Results: From April 27 to May 13, 2022, an epidemic of COVID-19 occurred in Haidian district. The strains isolated from the cases were identified by whole genome sequencing as Omicron variant (BA.2.2 evolutionary branch). A total of 38 infection cases were detected, including 34 confirmed cases and 4 asymptomatic cases. Most cases were mild ones (88.2%), no severe, critical or death cases occurred. The early clinical symptoms were mainly sore throat (50.0%) and cough (29.4%). The epidemic lasted for 17 days, resulting in 7 generations of the cases and involving 3 community transmissions, 2 working place transmissions and 8 family transmissions; the main infection routes were co-residence (47.6%) and co-space exposure (31.6%). The intergenerational interval M(Q1, Q3)was 3 (1, 6) days. The overall secondary attack rate was 1.5% (37/2 482), and the family secondary attack rate was 36.7% (18/49). Conclusions: The cases in this COVID-19 epidemic caused by Omicron variant had mild clinical symptoms, but the case clustering in families and communities was obvious, the transmission was rapid, and the risk for co-space exposure was high. It is necessary to use information technology to identify close contacts in the local population for the rapid and effective blocking of the epidemic spread.

[Survey on infection source of a cold-chain product associated COVID-19 epidemic caused by 2019-nCoV Delta variant in Beijing].

Objective: To investigate the source and the transmission chain of a cold-chain product associated COVID-19 epidemic caused by 2019-nCoV Delta variant in Beijing. Methods: Epidemiological investigation were used to verify the exposure points of the cases. Close contacts were traced from the exposure points, and human and environmental samples were collected for nucleic acid tests. Positive samples were analyzed by gene sequencing. Results: A total of 112 cases of COVID-19 were reported in the epidemic from January 18 to February 6, 2022 in Beijing. Except for 1 case was uncertain, there were epidemiological links among 111 cases. The source of infection was the packages of imported cold-chain products from Southeast Asia, which were harvested and stored in a local cold-storage in January 2021, and packaged and sent to the cold-storage A in A district in June 2021, and then sold in batches in cold-storage B in B district from January 2022. The first case was infected in the handling of positive frozen products, and then 77 cases occurred due to working, eating and living together with the index case in the cold-storage B, cold-storage C and restaurant D. Besides the cold-storage B, C and the restaurant D, there were 16 sub-transmission chains, resulting in additional 35 cases. Conclusion: The epidemic indicated that the risk of 2019-nCoV infection from imported cold-chain products contaminated by package and highlighted the importance to strengthen the management of cold-chain industry in future.

Upper Extremity Wounds Treated with Biodegradable Temporizing Matrix versus Collagen-Chondroitin Silicone Bilayer

Objective This study aims to compare outcomes between Novosorb Biodegradable Temporizing Matrix (BTM) and Integra collagen-chondroitin silicone for upper-extremity wound reconstruction. Methods This retrospective study analyzed adult patients who underwent wound reconstruction with either BTM or Integra at our institution between 2015 and 2020. Results Forty-eight patients were included: 31 (64.6%) BTM and 17 (35.4%) Integra. Mean age was 44.0 (range: 18-68) years. Age, race, sex, smoking, comorbidities, and defect size were similar between groups. Wound etiologies included 12 (25.0%) burn, 22 (45.8%) trauma, and others. Median template size was 133 cm 2for BTM and 104 cm 2for Integra (p = 0.526). Skin grafting was performed after 14 (45.2%) and 14 (82.4%) wounds treated with BTM and Integra, respectively (p = 0.028). Template complications of infection and dehiscence were comparable. Skin-graft complications occurred in five (35.7%) and three (21.4%) wounds in BTM and Integra, respectively (p = 0.031). Skin-graft failure rates were comparable (p = 0.121). Mean number of secondary procedures required after template placement was higher in the Integra group (BTM, 1.0;Integra, 1.9;p = 0.090). Final healing was achieved in 17 (54.8%) BTM and 11 (64.7%) Integra wounds (p = 0.694). Median time to healing was 4.1 months after BTM and 2.6 months after Integra placement (p = 0.014). Conclusion Compared with Integra, BTM achieved comparable wound healing and complication rates. Fewer secondary procedures and skin grafts were observed in BTM wounds, likely as a result of the coronavirus disease 2019 pandemic. At our institution, 100 cm 2of product costs $850 for BTM and $3,150 for Integra, suggesting BTM as an economical alternative to fulfill the high functional and aesthetic requirements of upper-extremity wounds. © 2022 Wolters Kluwer Medknow Publications. All rights reserved.

[Survey of possible aerosol transmission of a COVID-19 epidemic caused by 2019-nCoV Delta variant].

Objective: To investigate the epidemiological characteristics and the transmission chain of a family clustering of COVID-19 cases caused by severe acute respiratory 2019-nCoV Delta variant in Changping district of Beijing. Methods: Epidemiological investigation was conducted and big data were used to reveal the exposure history of the cases. Close contacts were screened according to the investigation results, and human and environmental samples were collected for nucleic acid tests. Positive samples were analyzed by gene sequencing. Results: On November 1, 2021, a total of 5 COVID-19 cases caused by 2019-nCoV Delta variant were reported in a family detected through active screening. The infection source was a person in the same designated isolation hotel where the first case of the family cluster was isolated from 22 to 27, October. The first case was possibly infected through aerosol particles in the ventilation duct system of the isolation hotel. After the isolation discharge on October 27, and the first case caused secondary infections of four family members while living together from October 27 to November 1, 2021. Conclusion: 2019-nCoV Delta variant is prone to cause family cluster, and close attention needs to be paid to virus transmission through ventilation duct system in isolation hotels.

[Survey on source of infection of the first local outbreak caused by SARS-CoV-2 Alpha variant in China].

Objective: To investigate the epidemiological characteristics and the chain of infection of a local outbreak, which was the first outbreak caused by severe acute respiratory syndrome corona virus 2 Alpha variant in China and occurred in Daxing district, Beijing. Methods: Epidemiological investigation and big data technology were used to verify the exposure points of the cases. Close contacts were traced from the exposure points, and their human and environmental samples were collected for nucleic acid tests. Serum samples were collected from key persons for antibody detection. Results: A total of 33 corona virus disease 2019(COVID-19) cases were reported in the local outbreak, from January 17, 2021 to January 29, 2021 in Daxing district, Beijing, and there was epidemiological association in 32 cases. Except for one case who was infected in the workplace, other cases were all infected in the community and family. All cases involved 14 families, of which 6 families were all infected. The attack rate of all family members was 69%(33/48), and the secondary attack rate was 56%(19/34). There was no obvious source of infection found after the investigation of entry-exit personnel and goods. Conclusion: The first outbreak caused by severe acute respiratory syndrome corona virus 2 Alpha variant in China is found and handled in time, and thus the scope of influence is limited, but the family clustering characteristics are more obvious than previous outbreaks.

Utility of electronic medical record dashboard on COVID-19 surgical volume

Introduction: An understanding of disruptions to health care delivery in real time is critical for monitoring volumes and outcomes. Currently outcomes are evaluated via timeconsuming reviews of patient records. This study aims to demonstrate the utility of a novel electronic medical record (EMR) dashboard via the impact of COVID-19 on pediatric otolaryngology procedures. Method: An EMR dashboard utilizing surgical encounters driven by Current Procedural Terminology groupings was used to enable real-time viewing of summaries and trends in a multicenter academic health system. The number of pediatric adenoidectomies, tonsillectomies, and tympanostomy tube placements (PETs) for an 11-month period was compared between 2019 and 2020 to assess COVID-19 impact. Return to emergency department (ED) within 30 days, 30-day readmission/observation rates, return to operating room (OR), and postoperative bleeding were assessed with chi-square analysis. Results: The EMR dashboard was reviewed for all patients <19 years for all providers and hospitals within the health system for defined procedure groupings. In 2019 264 adenoidectomies, 937 tonsillectomies, and 1134 PETs were performed vs a 2020 volume of 158, 563, and 664, respectively, at a 40% volume decline. For 2019 vs 2020, postoperative tonsillectomy bleed rates were 3.3% vs 5.2%;return to the ED rates were 11.1% vs 12.1%;30-day return to OR rates were 2.6% vs 4.6%;and observation/readmission rates were 2.2% vs 2.1% (P = .539). For all 3 procedures, no statistical difference was identified between years for any complication. There were no mortalities. Conclusion: In contrast to time-intensive chart review, the novel EMR dashboard confers rapid analysis and identification of surgical volumes for pediatric otolaryngology cases. Despite selection bias for more complicated cases due to cancellation of elective procedures, the EMR dashboard provides real-time reassurance that complication rates remained stable during the COVID-19 pandemic. We expect this EMR dashboard will improve our ability to monitor changes in surgical delivery.

Impact of COVID-19 on head and neck free flap volume

Introduction: This study aims to demonstrate the utility of a novel electronic medical record (EMR) dashboard by assessing the impact of COVID-19 on surgical volume and shortterm postoperative outcomes of head and neck surgical patients undergoing free flap reconstruction. Method: An EMR dashboard grouped surgical encounters by Current Procedural Terminology codes to view summaries and trends in real time at a tertiary academic institution. Outcomes of head and neck surgical patients undergoing microvascular free flap reconstruction, primarily for cancer diagnoses, were compared between 2019 and 2020 to assess COVID-19 impact. Hospital length of stay was assessed with t test, and 30-day return to emergency department (ED), readmission/ observation, return to operating room, and postoperative bleeding were assessed with Fisher exact test. Results: In 2019 190 free flap procedures were performed compared with 131 procedures in 2020, a 31.1% volume decline. Mean hospital length of stay for free flap procedures was 8.6 ± 6.0 days in 2019 and 9.1 ± 6.6 days in 2020 (P = .482). For 2019 vs 2020, return to ED rates were 21.6% vs 27.5% (P = .369);observation/readmission rates were 18.4% vs 10.7% (P = .117);postoperative hemorrhage rates were 5.8% vs 12.2% (P = .070);return to OR rates were 3.2% vs 8.4% (P = .753);and mortality rates were 0% vs 1.5% (P = .169), respectively. For all complications, there was no statistical difference detected between years. Conclusion: The novel EMR dashboard provided summaries of changes to surgical volume and postoperative outcomes in real time. Surgical volume for head and neck free flap procedures decreased significantly during the COVID-19 pandemic. Despite selection bias for more complicated cases due to cancellation of both elective and nonelective procedures, complication rates in our cohort remained stable indicating no adverse effects on patient safety.

[Relationship between respiratory viral load of cases of COVID-19 and secondary attack risk in close contacts].

Objective: To analyze the relationship between the cycle threshold (Ct) values of N gene of COVID-19 cases and the secondary attack risk in close contacts, and identify the relationship between respiratory viral load and infectivity in COVID-19 cases. Methods: The COVID-19 cases with records of Ct values of N gene within 0-7 days of onset were selected, and their close contacts were recruited as the subjects of study. We collected the information of close contacts, including name, gender, age, isolation mode, exposure mode and outcome (whether they were infected with SARS-CoV-2 or not) and other variables. Multivariate logistic regression models were used to identify the relationship between Ct values of N gene of COVID-19 cases and secondary attack risk in close contacts. Results: A total of 1 618 close contacts were recruited, in whom 77 were confirmed as symptomatic or asymptomatic COVID-19 patients with overall secondary attack rate of 4.8%. The multivariate logistic regression analysis indicated that eating together (OR=2.741, P=0.054), living together (OR=9.721, P<0.001), non-centralized isolation (OR=18.437, P<0.001) and COVID-19 case's values of N gene within 0-7 days of onset being <20 (OR=8.998, P=0.004) or 20-25 (OR=3.547, P=0.032) were significantly associated with higher likelihood of being infected with SARS-CoV-2 in close contacts. Conclusion: The results indicated that positive relationship exists between respiratory viral load and infectivity in COVID-19 cases, suggesting that Ct values of N gene can be used as an early warning indicator for the management of close contacts of COVID-19 cases.

Ring of disaster: Complication in percutaneous dilatational tracheostomy on ECMO

Introduction: Venous-venous extracorporeal membrane oxygenation (VV-ECMO) is becoming more utilized especially during the SARS-COV-2 pandemic. Although percutaneous dilatational tracheostomy (PDT) can be done and used safely to facilitate mechanical ventilation weaning, the procedure is associated with a higher complication rate when done in VV-ECMO patients. Case: 28-year-old male with past medical history significant for seizure disorder was transferred from outside hospital after getting treated for aspiration induced acute respiratory distress syndrome (ARDS). Decision was made to place the patient on VV-ECMO given refractory hypoxemia and hypercapnia with persistently high peak airway pressures. He was also placed on inhaled nitricoxide. Over the next 10 days, the patient was able to wean down to minimal ECMO settings. The decision was made to proceed with PDT to facilitate long term ventilation weaning. The tracheostomy was placed with minimal bleeding. Coagulopathy was optimized at that time. 24 hours after the procedure, the patient developed significant bleeding around the nasopharynx and the tracheostomy site. Patient's tidal volumes significantly decreased on pressure support ventilation leading to urgent inspection bronchoscopy. New clot burden was noted within the right bronchus intermedius. In addition, while entering the airway through the tracheostomy lumen, there was a valve-like ring of mucosal tissue that was semi-obstructing the lumen with each ventilation. The tissue was unable to be removed at the time. Unfortunately, the patient had a respiratory acidosis associated PEA arrest. He was able to regain pulse after 2 rounds of CPR and adjustment of sweep on ECMO. Second look bronchoscopy was done. Previously noted mucosal tissue appeared to be dislodged into the right main stem along with fibrous clot burden. Patient regained the previous tidal volume on the ventilator after the mucosal tissue and fibrous clot burden was removed. The bleeding was eventually controlled with supportive care. Eventually, the patient was able to be successfully decannulated from the ECMO and transferred back to the prior institution for further ventilation weaning. Discussion: ECMO patients often have increased hemorrhagic risk and post procedural complications given the circuit-blood interaction that affects coagulation and platelet function. Our case demonstrated rare potential severe complication peri-procedure. Insertion of a tracheostomy in an edematous airway can sheer mucosa and create the flap that can potentially lead to cardiac arrest. Early bronchoscopy surveillance may be warranted after PDT on patients with VV-ECMO to avoid unexpected complication. VV-ECMO setting should be adjusted when ventilation issues occur.

[Interpretation for the group standards in guidelines for personal protection against coronavirus disease 2019 for diseases control person].

As an emerging infectious disease, the COVID-19 threatened the safety of personnel in the prevention and control during the COVID-19 pandemic. Beijing Association of Preventive Medicine organizes the Beijing CDC and other organizations drafted the group standard entitled "Guidelines for personal protection against coronavirus disease 2019 for diseases control person (T/BPMA 0002-2020)" , according to years of scientific research on personal protection. Based on the principles of emphasizing the scientific, normative and safe nature, the standard was drafted to put forward the reasonable selection and correct use of personal protective equipment for disease control personnel, as well as the procedures for personal protective equipment. The standard provided a standardized basis for ensuring the safety of disease control personnel in contacting and handling of the new coronary pneumonia outbreaks with high risks.