Incidence and severity of SARS-CoV-2 reinfection, a multicenter cohort study in Shanghai, China.

During March 2022 to January 2023, two Omicron waves hit Shanghai and caused a massive number of reinfections. To better understand the incidence and clinical characteristics of SARS-CoV-2 reinfection in Shanghai, China, we conducted a multicenter cohort study. COVID-19 patients first infected with BA.2 (March 1, 2022-May 23, 2022) who were quarantined in Huashan Hospital, Renji Hospital, and Shanghai Jing'an Central Hospital were followed up for reinfection from June 1, 2022 to January 31, 2023. Of 897 primary infections, 148 (16.5%) experienced reinfection. Incidence rate of reinfection was 0.66 cases per 1000 person-days. Female gender (adjusted odds ratio [aOR]= 2.19, 95% confidence interval [CI]: 1.29-3.83) was a risk factor for reinfection. The four most common symptoms of reinfections during the circulation of BA.5 sublineages were cough (62.59%), sore throat (54.42%), fatigue (48.98%), and fever (42.57%). Having received a booster vaccination was not associated with reduced severity of reinfection in comparison with not having received booster vaccination. After matched 1:1 by age and sex, we found that reinfections with BA.5 sublineages had significantly lower occurrence and severity of fever, fatigue, sore throat, and cough, as compared to primary infections with BA.5 sublineages. SARS-CoV-2 Omicron reinfections were less severe than Omicron primary infections during the circulation of the same subvariant. Protection offered by both vaccination and previous infection was poor against SARS-CoV-2 reinfection.

Identification of Estradiol Benzoate as an Inhibitor of HBx Using Inducible Stably Transfected HepG2 Cells Expressing HiBiT Tagged HBx.

HBx plays a significant role in the cccDNA epigenetic modification regulating the hepatitis B virus (HBV) life cycle and in hepatocyte proliferation and carcinogenesis. By using the sleeping-beauty transposon system, we constructed a tetracycline-induced HBx-expressing stable cell line, SBHX21. HBx with a HiBiT tag can be quickly detected utilizing a NanoLuc-based HiBiT detection system. By screening a drug library using SBHX21 cells, we identified estradiol benzoate as a novel anti-HBx agent. Estradiol benzoate also markedly reduced the production of HBeAg, HBsAg, HBV pgRNA, and HBV DNA in a dose-dependent manner, suggesting that estradiol benzoate could be an anti-HBV agent. Docking model results revealed that estradiol benzoate binds to HBx at TRP87 and TRP107. Collectively, our results suggest that estradiol benzoate inhibits the HBx protein and HBV transcription and replication, which may serve as a novel anti-HBV molecular compound for investigating new treatment strategies for HBV infection.

Proportion of asymptomatic infection and nonsevere disease caused by SARS-CoV-2 Omicron variant: A systematic review and analysis.

SARS-CoV-2 Omicron variant seemed to cause milder disease compared to previous predominated variants. We aimed to conduct a meta-analysis to assess the pooled proportion of nonsevere disease and asymptomatic infection among COVID-19 patients infected with Omicron and Delta. We searched PubMed, Embase, Web of Science, and China National Knowledge Infrastructure (CNKI) databases. We included studies of SARS-CoV-2 Omicron infection from November 1, 2021, to April 18, 2022, and studies of Delta infection from October 1, 2020, to June 30, 2022. Studies without corresponding data, with less than 50 patients, or obviously biased concerning main outcome were excluded. Meta-analysis was performed in R 4.2.0 with the "meta" package. Subgroup analyses were conducted by study group and vaccination status. The pooled proportion of asymptomatic infection and nonsevere disease with Omicron were 25.5% (95% confidence interval [CI] 17.0%-38.2%) and 97.9% (95% CI 97.1%-98.7%), significantly higher than those of Delta with 8.4% (95% CI 4.4%-16.2%) and 91.4% (95% CI 87.0%-96.0%). During Omicron wave, children and adolescents had higher proportion of asymptomatic infection, SOTR and the elderly had lower proportion of nonsevere disease, vaccination of a booster dose contributed to higher proportion of both asymptomatic infection and nonsevere disease. This study estimates the pooled proportion of asymptomatic infection and nonsevere disease caused by SARS-CoV-2 Omicron compared to other predominant variants. The result has important implications for future policy making.

SARS-CoV-2 Omicron Variant: Epidemiological Features, Biological Characteristics, and Clinical Significance.

The SARS-CoV-2 Omicron (B.1.1529) variant was designated as a variant of concern (VOC) by the World Health Organization (WHO) on November 26, 2021. Within two months, it had replaced the Delta variant and had become the dominant circulating variant around the world. The Omicron variant possesses an unprecedented number of mutations, especially in the spike protein, which may be influencing its biological and clinical aspects. Preliminary studies have suggested that increased transmissibility and the reduced protective effects of neutralizing antibodies have contributed to the rapid spread of this variant, posing a significant challenge to control the coronavirus disease 2019 (COVID-19) pandemic. There is, however, a silver lining for this wave of the Omicron variant. A lower risk of hospitalization and mortality has been observed in prevailing countries. Booster vaccination also has ameliorated a significant reduction in neutralization. Antiviral drugs are minimally influenced. Moreover, the functions of Fc-mediated and T-cell immunity have been retained to a great extent, both of which play a key role in preventing severe disease.