Epidemiological characteristics of respiratory syncytial virus in hospitalized patients in Guangzhou from 2018 to 2022

Objective To analyze the epidemiological characteristics of respiratory syncytial virus（RSV） before and after the COVID-19 epidemic in Guangzhou in recent years. Methods Nasopharynx swabs from hospitalized patients with acute respiratory infection were collected from two sentinel hospitals in Guangzhou（Guangdong Maternal and Child Health Hospital and Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University） from 2018 to 2022. Luminex respiratory multi-pathogen detection technology was used to detect and type RSV in samples. Results A total of 1 243 nasopharyngeal swab samples were collected. The overall positive rate of RSV was 6. 11%（76/1 243）, including 39 RSV-A（51. 32%, 39/76） and 37 RSV-B（48. 68%, 37/76）. The highest detection rate of RSV in children under 3 years old was 8. 79%（66 cases）. Compared with 2018（8. 30%, 22/265） and 2020（14. 78%, 30/203）, the positive rate of RSV decreased significantly in 2019（3. 13%, 10/319）, 2021（4. 08%, 10/245） and 2022（1. 90%, 4/211）. Compared with 2018（8. 30%,22/265） and 2020（14. 78%,30/203）,the positive rate of RSV decreased significantly in 2019（3. 13%,10/319）, 2021（4. 08%,10/245） and 2022（1. 90%,4/211）. Type A prevailed in 2018（19/22） and 2022（4/4）, type B（25/30） prevailed in 2020, type A and type B coexisted in 2019 and 2021. The detection rate showed had no statistically significant seasonal difference except for 2020 [7. 14%（3/42）, 16. 39%（10/61）, 27. 12%（16/59）, 0（0/42）,χ~2= 16. 975,P＜0. 001]. Among all the 76 RSV positive samples, 17（22. 37%） showed multiple infections. Among them, human rhinovirus was the most common virus causing mixed infection, accounting for 58. 83%（10/17） of the mixed infection. Conclusion RSV is a common respiratory virus prevalent in Guangzhou, and children under 3 years old are the main population infected with RSV. RSV infection is prevalent every other year, with the characteristics of alternating epidemic of type A and type B, and the anti-seasonal epidemic appeared after the COVID-19. After the outbreak of COVID-19, the detection rate of RSV increased significantly in 2020. With the change of the national COVID-19 epidemic prevention and control policy, the detection rate of RSV declined significantly during 2021-2022.

Low infectious risk of re-positive COVID-19 patients: a single-center study.

OBJECTIVE: The aim of this study was to investigate the infectiousness of re-positive coronavirus disease 2019 (COVID-19) patients. METHODS: All nucleic acid testing (NAT) was performed using throat swabs, nasopharyngeal swabs, and anal swabs, which were tested by Fluorescent quantitative realtime PCR. Re-positive cases were defined as a discharged patient who re-tested positive by NAT. Micro-neutralization of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was performed based on the methods for severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS) viruses. IgM and IgG against the N protein of SARS-CoV-2 were determined by ELISA. RESULTS: A total 255 (16.04%) of 1590 COVID-19 patients were re-positive. The re-positive cases were more likely to occur in patients in the 20-39 years age group and in patients with disease of moderate severity. Quantitative PCR showed that cycle threshold (Ct) values and viral loads were both far lower than in the hospitalized COVID-19 patients. The viral load in re-positive cases was very low. Viral culture of the samples from re-positive patients showed no cytopathic effect, and NAT of the culture medium of viral cultures all exhibited negative results. CONCLUSION: The viral load in re-positive cases was very low; patients were not infectious and the risk of human-to-human transmission was extremely low. Discharged COVID-19 patients should undergo home health management for 3 weeks.

Parental psychosocial factors predicting adolescents' psychological adjustment during the surging and remission periods of COVID-19 in China: A longitudinal study.

BACKGROUND: Parents play a critical role in adolescents' psychological adjustment, especially in stress response. Few studies have investigated parental impact on adolescents' psychological adjustment in the pandemic. The longitudinal study examined how parental psychosocial factors at the surging period of the pandemic (T1) in China predicted adolescents' anxiety and depression concurrently and at the remission periods three (T2) and six months (T3) later. METHODS: Middle and high school students and their parents from three schools in Shanghai, China, completed online surveys on March 10, 2020 (T1), June 16, 2020 (T2), and Sep 25, 2020 (T3). Adolescents' anxiety/depression levels were assessed by matching self- and parent-reports at T1, T2, T3, and parents reported their psychological state (emotion and psychopathology), pandemic response (appraisal and coping), and perceived social support (PSS) at T1. RESULTS: Parental positive/negative emotions, anxiety, depression, control-appraisal, forward- and trauma-focus coping style and PSS were all significantly related to their children's anxiety/depression at T1. All factors, except coping style, predicted adolescents' anxiety/depression at T2 and T3, even after controlling for T1 adjustment levels. Parental positive emotion and depression had the strongest impact on adolescents' adjustment. LIMITATIONS: Some participants didn't complete the surveys at later time points, and the participants were only recruited in Shanghai. CONCLUSIONS: The study found that parents' psychosocial factors played a pivotal role on adolescents' psychological adjustment during COVID-19, highlighting the need to provide help to parents who were suffering from potential psychological distress.

Numerical investigation of airborne transmission of respiratory infections on the subway platform

Underground subway platforms are among the world’s busiest public transportation systems, but the airborne transmission mechanism of respiratory infections on these platforms has been rarely studied. Here, computational fluid dynamics (CFD) modeling is used to investigate the airflow patterns and infection risks in an island platform under two common ventilation modes: Mode 1- both sides have air inlets and outlets;Mode 2- air inlets are present at the two sides and outlets are present in the middle. Under the investigated scenario, airflow structure is characterized by the ventilation jet and human thermal plumes. Their interaction with the infector’s breathing jet imposes the front passenger under the highest exposure risk by short-range airborne route, with intake fractions up to 2.57% (oral breathing) or 0.63% (nasal breathing) under Mode 1;oral breathing of the infector may impose higher risks for the front passenger compared with nasal breathing. Pathogen are efficiently diluted as they travel further, in particular to adjacent crowds. The maximum and median value of intake fractions of passengers in adjacent crowds are respectively 0.093% and 0.016% (oral breathing), and 0.073% and 0.014% (nasal breathing) under Mode 1. Compared with Mode 1, the 2nd mode minimizes the interaction of ventilation jet and breathing jet, where the maximum intake fraction is only 0.34%, and the median value in the same crowd and other crowds are reduced by 23-63%. Combining published quanta generation rate data of COVID-19 and influenza infectors, the predicted maximum and median infection risks for passengers in the same crowds are respectively 1.46%−40.23% and 0.038%−1.67% during the 3−10 min waiting period, which are more sensitive to ventilation rate and exposure time compared with return air. This study can provide practical guidance for the prevention of respiratory infections in subway platforms.

A genome-wide CRISPR screen identifies host factors that regulate SARS-CoV-2 entry.

The global spread of SARS-CoV-2 is posing major public health challenges. One feature of SARS-CoV-2 spike protein is the insertion of multi-basic residues at the S1/S2 subunit cleavage site. Here, we find that the virus with intact spike (Sfull) preferentially enters cells via fusion at the plasma membrane, whereas a clone (Sdel) with deletion disrupting the multi-basic S1/S2 site utilizes an endosomal entry pathway. Using Sdel as model, we perform a genome-wide CRISPR screen and identify several endosomal entry-specific regulators. Experimental validation of hits from the CRISPR screen shows that host factors regulating the surface expression of angiotensin-converting enzyme 2 (ACE2) affect entry of Sfull virus. Animal-to-animal transmission with the Sdel virus is reduced compared to Sfull in the hamster model. These findings highlight the critical role of the S1/S2 boundary of SARS-CoV-2 spike protein in modulating virus entry and transmission and provide insights into entry of coronaviruses.