Kinetic Characteristics of Neutralizing Antibody Responses Vary among Patients with COVID-19 / 生物医学与环境科学（英文）

Objective@#The coronavirus disease 2019 (COVID-19) pandemic continues to present a major challenge to public health. Vaccine development requires an understanding of the kinetics of neutralizing antibody (NAb) responses to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2).@*Methods@#In total, 605 serum samples from 125 COVID-19 patients (from January 1 to March 14, 2020) varying in age, sex, severity of symptoms, and presence of underlying diseases were collected, and antibody titers were measured using a micro-neutralization assay with wild-type SARS-CoV-2.@*Results@#NAbs were detectable approximately 10 days post-onset (dpo) of symptoms and peaked at approximately 20 dpo. The NAb levels were slightly higher in young males and severe cases, while no significant difference was observed for the other classifications. In follow-up cases, the NAb titer had increased or stabilized in 18 cases, whereas it had decreased in 26 cases, and in one case NAbs were undetectable at the end of our observation. Although a decreasing trend in NAb titer was observed in many cases, the NAb level was generally still protective.@*Conclusion@#We demonstrated that NAb levels vary among all categories of COVID-19 patients. Long-term studies are needed to determine the longevity and protective efficiency of NAbs induced by SARS-CoV-2.

Epidemiological study of betel nut chewing among elementary and middle school students in Loudi city, Hunan province / 中华口腔医学杂志

<p><b>OBJECTIVE</b>To investigate the prevalence of betel nut chewing and oral submucous fibrosis (OSF) among elementary and middle school students in Loudi city, Hunan province.</p><p><b>METHODS</b>According to the standard of the third national oral health epidemiological investigation, the subjects were selected through a two-stage random sampling procedure. A face to face questionnaire survey was conducted among students by random sampling from 6 schools, and oral examination was performed to find the prevalence of OSF.</p><p><b>RESULTS</b>Of the 4087 eligible students, 4019 students participated in the survey(98.3%). Among the 4019 students, there were 498 betel nut chewers, the prevalence of betel nut chewing was 12.4%, which was much higher in male than in female students (437/2073, 21.1% vs 61/1946, 3.1%, P < 0.05). The proportion of students who were chewing areca nuts increased with increasing grades (P < 0.05). The prevalence was highest in senior schools (229/1077, 21.3%)and lowest in elementary schools (126/1983, 6.4%). Most students who were chewing areca nuts in elementary school obtained betel nuts from their parents (61/126, 48.4%), but most middle school betel nut chewers obtained betel nuts from their friends (88/143, 61.5% and 165/229, 72.1%). Five OSF cases (0.12%) were diagnosed among the 4019 students, all of them were male senior school students.</p><p><b>CONCLUSIONS</b>Betel nut chewing was common and OSF cases were found among elementary and middle school students in Loudi city. There were more male than female students who were chewing betel nut.</p>