https://twitter.com/Jimmy_Jeans/status/1442098694212538369
Use of face masks by non-scrubbed operating room staff: a randomized controlled trial
https://pubmed.ncbi.nlm.nih.gov/20575920/
“Exercise with facemask; Are we handling a devil's sword?” – A physiological hypothesis
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7306735/
Masks for prevention of viral respiratory infections among health care workers and the public: PEER umbrella systematic review
https://pubmed.ncbi.nlm.nih.gov/32675098/
Effectiveness of N95 respirators versus surgical masks against influenza: A systematic review and meta-analysis
Youlin Long 1 , Tengyue Hu 2 , Liqin Liu 2 , Rui Chen 3 , Qiong Guo 1 , Liu Yang 1 , Yifan Cheng 1 , Jin Huang 4 , Liang Du 1
Affiliations
PMID: 32167245 PMCID: PMC7228345 DOI: 10.1111/jebm.12381
Free PMC article
Abstract
Objective: Previous meta-analyses concluded that there was insufficient evidence to determine the effect of N95 respirators. We aimed to assess the effectiveness of N95 respirators versus surgical masks for prevention of influenza by collecting randomized controlled trials (RCTs).
Methods: We searched PubMed, EMbase and The Cochrane Library from the inception to January 27, 2020 to identify relevant systematic reviews. The RCTs included in systematic reviews were identified. Then we searched the latest published RCTs from the above three databases and searched ClinicalTrials.gov for unpublished RCTs. Two reviewers independently extracted the data and assessed risk of bias. Meta-analyses were conducted to calculate pooled estimates by using RevMan 5.3 software.
Results: A total of six RCTs involving 9 171 participants were included. There were no statistically significant differences in preventing laboratory-confirmed influenza (RR = 1.09, 95% CI 0.92-1.28, P .05), laboratory-confirmed respiratory viral infections (RR = 0.89, 95% CI 0.70-1.11), laboratory-confirmed respiratory infection (RR = 0.74, 95% CI 0.42-1.29) and influenzalike illness (RR = 0.61, 95% CI 0.33-1.14) using N95 respirators and surgical masks. Meta-analysis indicated a protective effect of N95 respirators against laboratory-confirmed bacterial colonization (RR = 0.58, 95% CI 0.43-0.78).
Conclusion: The use of N95 respirators compared with surgical masks is not associated with a lower risk of laboratory-confirmed influenza. It suggests that N95 respirators should not be recommended for general public and nonhigh-risk medical staff those are not in close contact with influenza patients or suspected patients.
https://pubmed.ncbi.nlm.nih.gov/32167245/
Adolescents' face mask usage and contact transmission in novel Coronavirus
Fang-Lin Chao 1
Affiliations
PMID: 32582579 PMCID: PMC7296276 DOI: 10.4081/jphr.2020.1771
Free PMC article
Abstract
The global outbreak of coronavirus has become an international public health threat. Prevention is of paramount importance to contain its spread. This study observes face mask wearing behavior and contact transmission problems in Taiwan. Teachers track student status in class. In addition to measuring body temperature and regular disinfection, classrooms require ventilation wear mask, provide alcohol spray and avoid sharing the microphone. Both questionnaire surveys and experimental were utilized. A total of 160 adults residing in Taiwan participated in the survey. The dye simulated the possible virus area on the mask surface during usage. Subjects were required to complete a questionnaire and simulate the spread of contact transmission when using a computer. Eighty-one % of respondents reported consistent use of surgical masks several times a day. They reported taking their masks off in relatively safe areas. Most people reported using one mask per day and storing the masks in their pockets. As a result, masks surface become a contamination source. In the contact experiment, ten adults were requested to don and doff a surgical mask while doing a word processing task. The extended contamination areas were recorded and identified by image analysis. The results show an average contamination area of the workspace is significant 530 cm2. When the hand touches the surface of the mask, it may spread the virus to the subsequent contact area.
https://pubmed.ncbi.nlm.nih.gov/32582579/
Conclusions
Although surgical masks are considered a viable means of protecting individuals from disease during an epidemic, accidental transmission through direct and indirect contact still puts face mask users at risk of infection. The survey of mask usage revealed the usage per day during an epidemic prevention period was 5.306 hours. Because most people repeatedly donned and doffed their masks, there was a high possibility of pollution during use. During the experiment, the subjects often had no specific place to store their masks, so they often stored the masks in their pockets, which might cause indirect contact transmission of pathogens. The average inconvenience of mask inhalation is high; and the mean value of hot and sultry is 4.025. A high degree of the agreement indicates that the smoothness of breathing is troublesome. The contact spread experiments show that the contaminated area varies considerably from user to user. The average polluted area of the ten subjects was 530 cm2. Hand contact is one of the transmission paths; when the hand touches the surface of the mask, it may spread the virus to the subsequent contact area, which is worthy of attention for general users.
CDC study: 85% of COVID-19 cases in July were people who often or always wear masks
https://www.theblaze.com/op-ed/horowitz-cdc-study-covid-masks
47 studies confirm the ineffectiveness of masks for COVID and 32 more confirm their negative health effects
https://www.lifesitenews.com/news/47-studies-confirm-inefectiveness-of-masks-for-covid-and-32-more-confirm-their-negative-health-effects/
Potent prophylactic and therapeutic efficacy of recombinant human ACE2-Fc against SARS-CoV-2 infection in vivo
COVID-19 has spread to more than two hundred countries, areas, or territories. Multiple therapeutic and prevention strategies are being developed against SARS-CoV-2 infection, including vaccines53–56, repurposed drugs7, convalescent plasma57,58, and neutralizing antibodies18–22. Blocking the binding of SARS-CoV-2 spike protein and its cell receptor hACE2 at the early stage of virus infection will be an effective approach. hACE2 fused with human IgG-Fc region may be a promising choice for early COVID-19 treatment since hACE2-Fc has a prolonged half-life in vivo and can maintain a proper blood concentration for long-term therapeutic effects35. Structural analysis indicated that hACE2 interacts with RBD of SARS-CoV-2 in the form of dimer, thus fusion of hACE2 with Fc may stabilize the structure of ACE2 for RBD binding59. Not only for SARS-CoV-2, but this approach might also work for other emerging virus infections. Once the cell receptor for the emerging virus is identified, the cellular receptor fused with Fc could be generated and expressed as a therapeutic drug rapidly.
Here, we demonstrated that hACE2-Fc, a recombinant hACE2 extracellular domain fused with Fc region, had a potent effect to neutralize SARS-CoV-2 authentic virus as efficiently as neutralizing antibodies. Importantly, we found that hACE2-Fc can neutralize most of VOCs (Alpha strain, Beta strain, and Delta strain) and a Variant of Interest (Kappa strain), which suggests the potential neutralization capacity of hACE2-Fc to more emerging SARS-CoV-2 variants with inscrutable public health threat. In addition, our results indicated that hACE2-Fc has broadly neutralizing activities against both HCoV-NL63 and SARS-CoV in vitro, although the antiviral activity of hACE2-Fc against SARS-CoV and HCoV-NL63 in vivo remained to be determined further. Besides, hACE2-Fc did not promote SARS-CoV-2 infection even at very low concentration. A study by Yeung et al.60 reported that soluble ACE2 may promote SARS-CoV-2 entry by forming an sACE2-S complex to enter cells through receptor-mediated endocytosis via the AT1 or forming an sACE2-S-vasopressin complex to enter cells via AVPR1B. We assumed that fusing with Fc region did not alter the binding of ACE2 to SARS-CoV-2 but obstruct the forming of complexes.
Moreover, hACE2-Fc can not only inhibit SARS-CoV-2 entry, but also inhibit SARS-CoV-2 spike-mediated cell–cell fusion, highlighting one more potential beneficial effect of hACE2-Fc in addition to blocking entry. The capacity of cell–cell fusion inhibition of hACE2-Fc was not as potent as blocking entry, indicating that blocking entry is essential for hACE2-Fc protective effect, while inhibiting cell–cell fusion may serve as an auxiliary capacity of hACE2-Fc. In addition, multiple SARS-CoV-2 variants are circulating globally, including B.1.1.7, B.1.351, B.1.617.2, and B.1.617.1. Some variants may be associated with an increased risk of transmission and death compared with the initial strain40,61. hACE2-Fc covers the entire binding site of RBD and ACE2, which greatly decreases the possibility of escaping by SARS-CoV-2 variants as well as diminishing the generation of escape mutants during patient treatment. It is potentially useful for the whole course of COVID-19 pandemic.
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https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8359631/
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Further, by using an Ad5-hACE2 transduction murine model for COVID-195, hACE2-Fc showed potent protective effects in SARS-CoV-2-infected mice. Prophylactic and therapeutic hACE2-Fc treatment strongly inhibited SARS-CoV-2 replication in lungs and prevented SARS-CoV-2-induced lung lesions. Most importantly, the protective effect of hACE2-Fc was dose-dependent and correlated with the result of PK in vivo, since the protective effect in therapeutic group was stronger than that in the prophylactic group. Recently, a case report provided encouraging data on the use of recombinant soluble hACE2 to treat a severe COVID-19 patient62. The data documented multiple significant improvement of the patient’s clinical complications after treatment, including decreased SARS-CoV-2 viral load and reduced inflammatory response. Notably, the use of hACE2 did not impede the generation of neutralizing antibodies63. Together, both our animal experiments and the case report indicate that recombinant soluble hACE2 could be a promising treatment for severe COVID-19.
Besides, two relevant studies have reported the half-life of hACE2-Fc in mice30,64. There are multiple known factors that may affect the PK value observed in hACE2-Fc test, including the sequence of Fc region of fusion protein, manufacture process (particularly the cell line used for expression, which significantly affects the post translational modification and in vivo PK) and animal model, etc. The half-life of hACE2-Fc (29.16 h) in mice is longer than that of soluble recombinant ACE2, which was 8.68 ± 0.79 h for soluble mouse ACE2 in mice (intraperitoneal administration) and 10 h for soluble hACE2 in healthy subjects (intravenous administration)35,52,65. The Fc region of hACE2-Fc may contribute to the in vivo retention time for making long-lasting effect for SARS-CoV-2 inhibition.
Mutations that inactivate ACE2’s catalytic activity did not reduce its protective effect in vivo against SARS-CoV-2. In this study, the catalytically inactive hACE2-Fc mutant also exhibited similar protective effect in vitro and in vivo. Engineering an optimal ACE2 protein with potent neutralizing activity against SARS-CoV-2 and prolonged half-life20,33 is the major goal for ACE2-derived therapeutic drug development for COVID-19. In summary, the data presented here demonstrated the efficacy of hACE2-Fc in prophylactic and therapeutic treatment regimens in vivo, which is a potentially excellent candidate for COVID-19 therapy.