To date, at least three lineages (Lineage 1–3) that are related to recombinant human adenovirus species C (HAdV-C) have been identified in China. Among them, Lineage 1 includes two Chinese strains, strain KR699642-CHN-20093 (CBJ11) and strain MF315029-CHN-2013 (BJ09), which were collected in Beijing in 2009 and 2013, respectively. Herein, we performed genomic and bioinformatics analysis of two HAdV-C strains (strain SX-2000-140 and strain SX-2004-327) that were isolated from the feces of two healthy children in Shanxi province of China in 2000 and 2004, respectively. Results revealed that the genomes of both Shanxi strains had the highest homology to two Chinese HAdV-C strains belonging to Lineage 1 and harbored the genetic elements of these two strains, thereby presuming that Lineage1 has been circulated in mainland of China for decades. In addition, though the viruses in Lineage 1 showed slightly different recombinant patterns resulting from the recombinant events among the five types of HAdV-C, all the Lineage 1 viruses shared the highest sequence similarities with the HAdV-2 prototype strain (NC_001405-USA-1953) across the genome, especially in the major capsid genes including hexon, and fiber. These results indicated that Lineage 1 viruses that were associated with recombinants shared a common ancestor that is closely related to the HAdV-2 virus. Our current findings confirmed that frequent recombination among the different HAdV-C types might be an important driving force for the molecular evolution of HAdV-C. Therefore, there is a strong need for further comprehensive and systematic monitoring, detection, and research on HAdV-C.

Background In mainland China, seasonal influenza disease burden at community level is unknown. The incidence rate of influenza virus infections in the community is difficult to determine due to the lack of well‐defined catchment populations of influenza‐like illness surveillance sentinel hospitals. Objectives We established a community‐based cohort to estimate incidence of seasonal influenza infections indicated by serology and protection conferred by antibody titers against influenza infections during 2018‐2019 influenza season in northern China. Methods We recruited participants in November 2018 and conducted follow‐up in May 2019 with collection of sera every survey. Seasonal influenza infections were indicated by a 4‐fold or greater increase of hemagglutination inhibition (HI) antibody between paired sera. Results Two hundred and three children 5‐17 years of age and 413 adults 18‐59 years of age were followed up and provided paired sera. The overall incidence of seasonal influenza infection and incidence of A(H3N2) infection in children (31% and 17%, respectively) were significantly higher than those in adults (21% and 10%, respectively). The incidences of A(H1N1)pdm09 infection in children and adults were both about 10%, while the incidences of B/Victoria and/Yamagata infection in children and adults were from 2% to 4%. HI titers of 1:40 against A(H1N1)pdm09 and A(H3N2) viruses were associated with 63% and 75% protection against infections with the two subtypes, respectively. Conclusions In the community, we identified considerable incidence of seasonal influenza infections. A HI titer of 1:40 could be sufficient to provide 50% protection against influenza A virus infections indicated by serology.

Background Shigella spp., facultative anaerobic bacilli of the family Enterobacteriaceae , are one of the most common causes of diarrheal diseases in human worldwide which have become a significant public health burden. So, we aimed to analyze the antimicrobial phenotypes and to elucidate the molecular mechanisms underlying resistance to cephalosporins and fluoroquinolones in Shigella isolates from patients with diarrhea in Shanxi Province. Results During 2006–2016, we isolated a total of 474 Shigella strains (including 337 S. flexneri and 137 S. sonnei ). The isolates showed high rates of resistance to traditional antimicrobials, and 26, 18.1 and 3.0% of them exhibited resistance to cephalosporins, fluoroquinolones and co-resistance to cephalosporins and fluoroquinolones, respectively. Notably, 91.1% of these isolates, including 22 isolates that showed an ACTSuT profile, exhibited multidrug resistance (MDR). The resistance rates to cephalosporins in S. sonnei isolates were higher than those in S. flexneri. Conversely, the resistance rates to fluoroquinolones were considerably higher in S. flexneri isolates. Among the 123 cephalosporins-resistant isolates, the most common extended-spectrum beta-lactamase gene was bla TEM-1 , followed by bla CTX-M , bla OXA-1 , and bla SHV-12 . Six subtypes of bla CTX-M were identified, bla CTX-M-14 ( n = 36) and bla CTX-M-55 ( n = 26) were found to be dominant. Of all the 86 isolates with resistance to fluoroquinolones and having at least one mutation (Ser83Leu, His211Tyr, or Asp87Gly) in the the quinolone resistance-determining regions of gyr A, 79 also had mutation of par C (Ser80Ile), whereas 7 contained plasmid-mediated quinolone resistance genes including qnr A, qnr B, qnr S, and aac(60)-Ib-cr. Furthermore, pulsed-field gel electrophoresis analysis (PFGE) showed a considerable genetic diversity in S. flexneri isolates. However, the S. sonnei isolates had a high genetic similarity. Conclusions Coexistence of diverse resistance genes causing the emergence and transmission of MDR might render the treatment of shigellosis difficult. Therefore, continuous surveillance might be needed to understand the actual disease burden a...

Background As one of the non-pharmacological interventions to control the transmission of COVID-19, determining the quarantine duration is mainly based on the accurate estimates of the incubation period. However, patients with coarse information of the exposure date, as well as infections other than the symptomatic, were not taken into account in previously published studies. Thus, by using the statistical method dealing with the interval-censored data, we assessed the quarantine duration for both common and uncommon infections. The latter type includes the presymptomatic, the asymptomatic and the recurrent test positive patients. Methods As of 10 December 2020, information on cases have been collected from the English and Chinese databases, including Pubmed, Google scholar, CNKI (China National Knowledge Infrastructure) and Wanfang. Official websites and medias were also searched as data sources. All data were transformed into doubly interval-censored and the accelerated failure time model was applied. By estimating the incubation period and the time-to-event distribution of worldwide COVID-19 patients, we obtain the large percentiles for determining and suggesting the quarantine policies. For symptomatic and presymptomatic COVID-19 patients, the incubation time is the duration from exposure to symptom onset. For the asymptomatic, we substitute the date of first positive result of nucleic acid testing for that of symptom onset. Furthermore, the time from hospital discharge or getting negative test result to the positive recurrence has been calculated for recurrent positive patients. Results A total of 1920 laboratory confirmed COVID-19 cases were included. Among all uncommon infections, 34.1% (n = 55) of them developed symptoms or were identified beyond fourteen days. Based on all collected cases, the 95th and 99th percentiles were estimated to be 16.2 days (95% CI 15.5–17.0) and 22.9 days (21.7‒24.3) respectively. Besides, we got similar estimates based on merely symptomatic and presymptomatic infections as 15.1 days (14.4‒15.7) and 21.1 days (20.0‒22.2). Conclusions There are a certain number of infected people who require longer quarantine duration. Our findings well support the current practice of the extended active monitoring. To further prevent possible transmissions induced and facilitated by such infectious outliers after the 14-days quarantine, properly prolonging the quarantine duration could be prudent for high-risk scenarios and in regions with insufficient test resources.

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