Ερευνητές των πανεπιστημίων ΜΙΤ και Χάρβαρντ (Wyss Institute for Biologically Inspired Engineering) στις ΗΠΑ δημιούργησαν μια πρωτοποριακή μάσκα προσώπου, η οποία μπορεί μέσα σε περίπου 90 λεπτά να κάνει ακριβή διάγνωση αν αυτός που τη φοράει, έχει μολυνθεί από τον κορωνοϊό. Η διαγνωστική μάσκα, χάρη στους ειδικούς μικροσκοπικούς βιοαισθητήρες που είναι ενσωματωμένοι σε αυτήν και αναλύουν την αναπνοή, είναι τόσο ευαίσθητη και ακριβής όσο ένα μοριακό τεστ PCR για τον κορωνοϊό και τόσο γρήγορη όσο ένα rapid τεστ αντιγόνου, σύμφωνα με τους δημιουργούς της.
Η ίδια διαγνωστική τεχνολογία (wearable freeze-dried cell-free ή wFDCF), η οποία άρχισε να αναπτύσσεται το 2015 και εξελίχτηκε προοδευτικά, θα μπορούσε να αξιοποιηθεί γενικότερα για να δημιουργηθούν υφάσματα και ρούχα που να ανιχνεύουν όχι μόνο τον ιό SARS-CoV-2, αλλά επίσης άλλους παθογόνους μικροοργανισμούς (ιοί γρίπης, Έμπολα, Ζίκα κ.α.).
Οι επιστήμονες διαπίστωσαν ότι οι αισθητήρες που μπορούν να διαγνώσουν ιούς, είναι δυνατό να ενσωματωθούν όχι μόνο σε διάφορες μάσκες προσώπου, αλλά επίσης σε ποδιές εργαστηρίου και σε άλλα ρούχα, παρέχοντας έτσι ένα νέο τρόπο για να παρακολουθείται η έκθεση των εργαζομένων στο βιοϊατρικό τομέα σε διάφορες απειλές για την υγεία τους.
«Δείξαμε ότι μπορούμε να αναπτύξουμε μια ευρεία γκάμα αισθητήρων συνθετικής βιολογίας για να ανιχνεύουμε ιούς ή βακτήρια, καθώς και τοξικά χημικά, όπως οι νευρικές τοξίνες. Προσβλέπουμε ότι έτσι θα δημιουργήσουμε φορετούς βιοαισθητήρες επόμενης γενιάς για διασώστες, υγειονομικό και στρατιωτικό προσωπικό», δήλωσε ο καθηγητής βιοϊατρικής μηχανικής Τζέημς Κόλλινς του ΜΙΤ, επικεφαλής της ερευνητικής ομάδας.
«Ουσιαστικά συρρικνώσαμε ένα ολόκληρο διαγνωστικό εργαστήριο σε ένα μικρό αισθητήρα συνθετικής βιολογίας που λειτουργεί σε οποιαδήποτε μάσκα προσώπου και συνδυάζει την υψηλή ακρίβεια των μοριακών τεστ PCR με την ταχύτητα και το χαμηλό κόστος των τεστ αντιγόνου. Πέρα από τις μάσκες, οι προγραμματίσιμοι αισθητήρες μας μπορούν να ενσωματωθούν σε άλλα υφάσματα», δήλωσε ο δρ. Πίτερ Νγκουγιέν του Χάρβαρντ.
Οι αισθητήρες, οι οποίοι είναι τοποθετημένοι στο εσωτερικό της μάσκας και αναλύουν την αναπνοή του χρήστη, μπορούν να ενεργοποιηθούν κατά βούληση από αυτόν που τη φοράει. Τα αποτελέσματα της διάγνωσης φανερώνονται μόνο στο εσωτερικό της μάσκας, για λόγους προστασίας των προσωπικών δεδομένων.
Όταν οι αισθητήρες τοποθετούνται στο εξωτερικό μέρος της μάσκας, τότε μπορούν να ανιχνεύσουν τοξικές χημικές ουσίες στο περιβάλλον. Στο μέλλον αναμένεται ότι μικροσκοπικές οπτικές ίνες θα ενσωματωθούν στους αισθητήρες και, όταν γίνεται ανίχνευση μικροβίων ή τοξινών, τα αντίστοιχα ψηφιακά σήματα θα στέλνονται σε μια εφαρμογή κινητού τηλεφώνου(app).
Οι ερευνητές έχουν ήδη καταθέσει τη σχετική πατέντα για την τεχνολογία τους και αναζητούν εταιρεία για να συνεργαστούν, προκειμένου να αναπτύξουν περαιτέρω τους αισθητήρες τους. Η διαγνωστική μάσκα προσώπου αναμένεται να είναι η πρώτη εμπορική εφαρμογή που θα κυκλοφορήσει στην αγορά.
Naftemporiki.gr με πληροφορίες από ΑΠΕ-ΜΠΕ
An evidence review of face masks against COVID-19
View ORCID ProfileJeremy Howard, Austin Huang, View ORCID ProfileZhiyuan Li, View ORCID ProfileZeynep Tufekci, Vladimir Zdimal, View ORCID ProfileHelene-Mari van der Westhuizen, View ORCID ProfileArne von Delft, View ORCID ProfileAmy Price, Lex Fridman, View ORCID ProfileLei-Han Tang, View ORCID ProfileViola Tang, View ORCID ProfileGregory L. Watson, View ORCID ProfileChristina E. Bax, View ORCID ProfileReshama Shaikh, View ORCID ProfileFrederik Questier, Danny Hernandez, View ORCID ProfileLarry F. Chu, View ORCID ProfileChristina M. Ramirez, and View ORCID ProfileAnne W. Rimoin
See all authors and affiliations
PNAS January 26, 2021 118 (4) e2014564118; https://doi.org/10.1073/pnas.2014564118
Edited by Lauren Ancel Meyers, The University of Texas at Austin, Austin, TX, and accepted by Editorial Board Member Nils C. Stenseth December 5, 2020 (received for review July 13, 2020)
Article Figures & SI Info & Metrics PDF
Abstract
The science around the use of masks by the public to impede COVID-19 transmission is advancing rapidly. In this narrative review, we develop an analytical framework to examine mask usage, synthesizing the relevant literature to inform multiple areas: population impact, transmission characteristics, source control, wearer protection, sociological considerations, and implementation considerations. A primary route of transmission of COVID-19 is via respiratory particles, and it is known to be transmissible from presymptomatic, paucisymptomatic, and asymptomatic individuals. Reducing disease spread requires two things: limiting contacts of infected individuals via physical distancing and other measures and reducing the transmission probability per contact. The preponderance of evidence indicates that mask wearing reduces transmissibility per contact by reducing transmission of infected respiratory particles in both laboratory and clinical contexts. Public mask wearing is most effective at reducing spread of the virus when compliance is high. Given the current shortages of medical masks, we recommend the adoption of public cloth mask wearing, as an effective form of source control, in conjunction with existing hygiene, distancing, and contact tracing strategies. Because many respiratory particles become smaller due to evaporation, we recommend increasing focus on a previously overlooked aspect of mask usage: mask wearing by infectious people (“source control”) with benefits at the population level, rather than only mask wearing by susceptible people, such as health care workers, with focus on individual outcomes. We recommend that public officials and governments strongly encourage the use of widespread face masks in public, including the use of appropriate regulation.
COVID-19SARS-CoV-2maskspandemic
Policy makers need urgent guidance on the use of masks by the general population as a tool in combating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the respiratory virus that causes COVID-19. Masks have been recommended as a potential tool to tackle the COVID-19 pandemic since the initial outbreak in China (1), although usage during the outbreak varied by time and location (2). Globally, countries are grappling with translating the evidence of public mask wearing to their contexts. These policies are being developed in a complex decision-making environment, with a novel pandemic, rapid generation of new research, and exponential growth in cases and deaths in many regions. There is currently a global shortage of N95/FFP2 respirators and surgical masks for use in hospitals. Simple cloth masks present a pragmatic solution for use by the public. This has been supported by most health bodies. We present an interdisciplinary narrative review of the literature on the role of face masks in reducing COVID-19 transmission in the community.
Background
Wu Lien Teh’s work to control the 1910 Manchurian Plague has been acclaimed as “a milestone in the systematic practice of epidemiological principles in disease control” (3), in which Wu identified the cloth mask as “the principal means of personal protection.” Although Wu designed the cloth mask that was used through most of the world in the early 20th century, he pointed out that the airborne transmission of plague was known since the 13th century, and face coverings were recommended for protection from respiratory pandemics since the 14th century (4). Wu reported on experiments that showed a cotton mask was effective at stopping airborne transmission, as well as on observational evidence of efficacy for health care workers. Masks have continued to be widely used to control transmission of respiratory infections in East Asia through to the present day, including for the COVID-19 pandemic (5).
In other parts of the world, however, mask usage in the community had fallen out of favor, until the impact of COVID-19 was felt throughout the world, when the discarded practice was rapidly readopted. By the end of June 2020, nearly 90% of the global population lived in regions that had nearly universal mask use, or had laws requiring mask use in some public locations (6), and community mask use was recommended by nearly all major public health bodies. This is a radical change from the early days of the pandemic, when masks were infrequently recommended or used.
Direct Evidence of the Efficacy of Public Mask Wearing
If there is strong direct evidence, either a suitably powered randomized controlled trial (RCT), or a suitably powered metaanalysis of RCTs, or a systematic review of unbiased observational studies that finds compelling evidence, then that would be sufficient for evaluating the efficacy of public mask wearing, at least in the contexts studied. Therefore, we start this review looking at these types of evidence.
Direct Epidemiological Evidence.
Cochrane (7) and the World Health Organization (8) both point out that, for population health measures, we should not generally expect to be able to find controlled trials, due to logistical and ethical reasons, and should therefore instead seek a wider evidence base. This issue has been identified for studying community use of masks for COVID-19 in particular (9). Therefore, we should not be surprised to find that there is no RCT for the impact of masks on community transmission of any respiratory infection in a pandemic.
Only one observational study has directly analyzed the impact of mask use in the community on COVID-19 transmission. The study looked at the reduction of secondary transmission of SARS-CoV-2 in Beijing households by face mask use (10). It found that face masks were 79% effective in preventing transmission, if they were used by all household members prior to symptoms occurring. The study did not look at the relative risk of different types of mask.
In a systematic review sponsored by the World Health Organization, Chu et al. (11) looked at physical distancing, face masks, and eye protection to prevent person-to-person transmission of SARS-CoV-2. They found that “face mask use could result in a large reduction in risk of infection.” However, the review included only three studies of mask use outside health care settings, all of which were of SARS, not of SARS-CoV-2, one of which was incorrectly categorized (it occurred in a hospital, but during family and friend visits), and one of which found that none of the households wearing masks had any infections, but was too underpowered to draw any conclusions (12). The remaining study found the use of masks was strongly protective, with a risk reduction of 70% for those that always wore a mask when going out (13), but it did not look at the impact of masks on transmission from the wearer. It is not known to what degree analysis of other coronaviruses can be applied to SARS-CoV-2. None of the studies looked at the relative risks of different types of mask.
There has been one controlled trial of mask use for influenza control in the general community (14). The study looked at Australian households, was not done during a pandemic, and was done without any enforcement of compliance. It found that “in an adjusted analysis of compliant subjects, masks as a group had protective efficacy in excess of 80% against clinical influenza-like illness.” However, the authors noted that they “found compliance to be low, but compliance is affected by perception of risk. In a pandemic, we would expect compliance to improve.” In compliant users, masks were highly effective at reducing transmission.
Overall, evidence from RCTs and observational studies is informative, but not compelling on its own. Both the Australian influenza RCT and the Beijing households observational trial found around 80% efficacy among compliant subjects, and the one SARS household study of sufficient power found 70% efficacy for protecting the wearer. However, we do not know whether the results from influenza or SARS will correspond to results for SARS-CoV-2, and the single observational study of SARS-CoV-2 might not be replicated in other communities. None of the studies looked specifically at cloth masks.
Freegr network blog- News about pc, technology.
freegr
