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ObjectivesTo evaluate the risk of exposure to SARS-CoV-2 in naturally ventilated hospital settings by measuring parameters of ventilation and comparing these findings with results of bioaerosol sampling.Study designCross-sectional study.Study setting and study sampleThe study sample included nine hospitals in Dhaka, Bangladesh. Ventilation characteristics and air samples were collected from 86 healthcare spaces during October 2020 to February 2021.Primary outcomeRisk of cumulative SARS-CoV-2 infection by type of healthcare area.Secondary outcomesVentilation rates by healthcare space; risk of airborne detection of SARS-CoV-2 across healthcare spaces; impact of room characteristics on absolute ventilation; SARS-CoV-2 detection by naturally ventilated versus mechanically ventilated spaces.ResultsThe majority (78.7%) of naturally ventilated patient care rooms had ventilation rates that fell short of the recommended ventilation rate of 60 L/s/p. Using a modified Wells-Riley equation and local COVID-19 case numbers, we found that over a 40-hour exposure period, outpatient departments posed the highest median risk for infection (7.7%). SARS-CoV-2 RNA was most frequently detected in air samples from non-COVID wards (50.0%) followed by outpatient departments (42.9%). Naturally ventilated spaces (22.6%) had higher rates of SARS-CoV-2 detection compared with mechanically ventilated spaces (8.3%), though the difference was not statistically significant (p=0.128). In multivariable linear regression with calculated elasticity, open door area and cross-ventilation were found to have a significant impact on ventilation.ConclusionOur findings provide evidence that naturally ventilated healthcare settings may pose a high risk for exposure to SARS-CoV-2, particularly among non-COVID-designated spaces, but improving parameters of ventilation can mitigate this risk.

Mohammad Ali Moni) 14 15 ABSTRACT 16 17 An outbreak, caused by a RNA virus, SARS-CoV-2 named COVID-19 has become pandemic with a 18 magnitude which is daunting to all public health institutions in the absence of specific antiviral 19 treatment. Surface glycoprotein and nucleocapsid phosphoprotein are two important proteins of this 20 virus facilitating its entry into host cell and genome replication. Small interfering RNA (siRNA) is a 21 prospective tool of the RNA interference (RNAi) pathway for the control of human viral infections 22 by suppressing viral gene expression through hybridization and neutralization of target 23 complementary mRNA. So, in this study, the power of RNA interference technology was harnessed 24 to develop siRNA molecules against specific target genes namely, nucleocapsid phosphoprotein 25 gene and surface glycoprotein gene. Conserved sequence from 139 SARS-CoV-2 strains from 26 around the globe was collected to construct 78 siRNA that can inactivate nucleocapsid 27 phosphoprotein and surface glycoprotein genes. Finally, based on GC content, free energy of 28folding, free energy of binding, melting temperature and efficacy prediction process 8 siRNA 29molecules were selected which are proposed to exerts the best action. These predicted siRNAs 30 should effectively silence the genes of SARS-CoV-2 during siRNA mediated treatment assisting in 31 the response against SARS-CoV-2 32 33

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The prevalence of fecal colonization with extended-spectrum β-lactamase-producing Escherichia coli (ESBL-Ec) among children in low- and middle-income countries is alarmingly high. This study aimed to identify the sources of ESBL-Ec colonization in children < 1 year old through comparative analysis of E. coli isolates from child stool, child’s mother stool, and point-of-use drinking water from 46 rural households in Bangladesh. The pairwise similarity in antibiotic susceptibility of E. coli from all three sources was evaluated, followed by phylogenetic clustering using enterobacterial repetitive intergenic consensus polymerase chain reaction and whole-genome sequence analysis of the isolates. Matching antibiotic susceptibility and enterobacterial repetitive intergenic consensus polymerase chain reaction patterns were found among ESBL-Ec isolates from child–mother dyads of 24 and 11 households, respectively, from child–water dyads of 5 and 4 households, respectively, and from child–mother–water triads of 3 and 4 households, respectively. Whole-genome sequence analysis of 30 isolates from 10 households revealed that ESBL-Ec from children in five households (50%) was clonally related to ESBL-Ec either from their mothers (2 households), drinking water sources (2 households), or both mother and drinking-water sources (1 household) based on serotype, phylogroup, sequence type, antibiotic resistance genes, mobile genetic elements, core single-nucleotide polymorphisms, and whole-genome multilocus sequence typing. Overall, this study provides empirical evidence that ESBL-Ec colonization in children is linked to the colonization status of mothers and exposure to the household environments contaminated with ESBL-Ec. Interventions such as improved hygiene practices and a safe drinking water supply may help reduce the transmission of ESBL-Ec at the household level.