Covid-19 and protective masks. Which ones to choose, for common and professional use? When, how and why to use them, with the aim of protecting us and others from the transmission of Coronavirus? The ABC to follow.
Masks, three categories
Three types of masks protectors are essentially available on the market, each with its own function.
1) Cloth masks. Made of cotton or synthetic materials, the cloth mask they are used in some work environments (eg food industry) as a basic hygiene practice.
2) Surgical masks. THE clinicalmask they are not medical devices designed to prevent the spread of infections, as they do not seal the face, and their effectiveness varies in relation to the filtration capacity.
3) Respirators, with and without filter. THE respirator they are the only devices specifically designed to protect the individual from respiratory infections. They seal the face, around the nose and mouth.
Masks and respirators, the difference
The masks of tissue, such as surgical ones are called 'face masks' (facemask). They are not designed to protect the wearer's respiratory tract and offer no guarantees in this regard. Their use was also recommended - as a minimum barrier, 'always better than nothing'- in some epidemic contexts where surgical or respiratory masks were not available. (1)
The respirators are classified as PPE (Personal Protective Equipment, or PPE, Personal protective equipment). They are governed by international standards and subject to specific certifications which it is always advisable (in the professional sphere) to verify the reliability. They are classified on the basis of their filtering efficiency (FF), on a scale that goes from P1 to P3. The FFP2 and FFP3 models are best suited for virus protection. (2) The N95 code indicates the ability to block at least 95% of very small particles (0,3 microns) and is also available in the version for surgical use.
Masks, the general function
The general function of masks is above all to limit the risk of spreading infections when worn by infected people. Which, it should be remembered, can transmit some viruses even before the onset of symptoms or in their absence (in 44% of cases, according to a very recent observational study conducted by Department of Science and Technology of Guandong Province, China). (3)
The diffusion of the influenza virus from a sick patient wearing surgical masks or N95, according to an experimental study, can actually be reduced. (4) Another study conducted on volunteers with flu symptoms showed that their use of a surgical mask could reduce the emissions of viral particles by three times. (5) On the other hand, the widespread use of cloth and surgical masks has proven effective in mitigating the SARS epidemic in Taiwan. (6) So in Hong Kong, where 76% of the population wore them. (7)
Frequent and thorough hand washing, as seen, however, is essential precisely in order to reduce the risk of contagion through contact of contaminated hands with eyes, nose and mouth. To the point that in the numerous studies conducted on ongoing communities of various viral phenomena it is difficult to attribute a preponderant preventive role to the use of the mask.
Vulnerable people, the function of masks
The most vulnerable people - seniors (over-65), the immunocompromised and people with other pathologies (eg cardiocirculatory and neurological, diabetes, etc.) - must avoid external contacts or in any case reduce them to an essential minimum. And it is therefore that the 'Cura Italia' decree gives them priority in agile work (or teleworking). However, they must often wash their hands, in this epidemic phase, and live in environments with surfaces and objects sanitized frequently.
It is recommended in any case to these subjects - as they are more exposed to the contagion and the consequences of the coronavirus - to wear a mask, if they are forced to leave the house. As was recommended by health institutions in 2009, at the time of the so-called avian flu. (8) And in previous studies on how to mitigate the effects of epidemics on vulnerable groups of the population. (9)
Égalité launched a petition - which we invite everyone to sign, following this link - to solicit supermarkets and operators ecommerce to guarantee the free delivery of shopping to the disabled, immunocompromised e over-65. Precisely in order to avoid them the tiring and dangerous trips otherwise necessary to purchase essential goods.
Devices to be used in the workplace, a duty watered down in Protocol 14.3.20
Randomized clinical trials suggest the general protective role of masks (facemask) against infections in various community contexts, within the limits of compliance of the masks and their early use in case of infections. Which must be constant during the coronavirus emergency, in the opinion of the writer, where companies continue their production activities.
Il Protocol signed on 14.3.20 by the social partners, in Italy, limits itself to providing for compliance with the WHO recommendations on the use of masks. The bare minimum but certainly not enough, here and now, to prevent serious damage to workers' health. In addition to the contagion of third parties and entire communities. (10) With as many risks, for the legal representatives of companies, of conviction for serious crimes.
Worker safety, mask or respirator?
The scientific evidence demonstrates how respirators offer superior protection to masks (facemask). They are therefore indispensable for health workers and also for workers who unfortunately the Protocol 14.3.20 admits can work at interpersonal distances lower than the minimum safety one (1 meter). All the more so as they are exposed to contacts with a plurality of people.
A surgical mask it can be effective in blocking splashes and droplets of large particles, but it cannot filter out very small particles released into the air by coughing and sneezing from nearby people. Nor can it provide complete protection from germs and other contaminants, due to lack of complete adhesion between the face mask surface and the face.
A scientific study conducted on healthcare professionals showed how N95 respirators significantly reduce the risk of bacterial colonization both with respect to the non-use of any protection (-62%), and in comparison with surgical masks (-46%). Which therefore proved to be ineffective for this purpose. The researchers then demonstrated how N95 masks can significantly reduce the risk - identified as common, among health workers - of simultaneous infection with bacteria and viruses. (11)
Italy, mask emergency. ISS ready
The Ministry of Health, in circular 13.3.20, highlighted that surgical masks in 'non-woven fabric' (TNT), in order to be used as medical devices, must meet the following characteristics:
- compliance to UNI EN ISO 14683, UNI EN ISO 10993 standards,
- production by companies with a (certified) quality system. (12)
The DL 2.3.20 he had also authorized the Civil Protection, until the end of the emergency period, to purchase personal protective equipment and other medical devices - including masks - even without the CE mark, subject to evaluation by the ISS (Istituto Superiore di Sanità). (13 ) The COVID-19 Medical Devices Working Group he was therefore in charge of evaluating the suitability of face masks for medical use, even if without the CE mark. In view of their use in derogation, limited to the emergency period. Interested operators can address their requests by writing to the email address maskecovid-19@pec.iss.it.
Isolation and incubation period, latest studies
A very recent study analyzes the evolution of the COVID-19 contagion, comparing the Chinese example of rigorous quarantine (in Wuhan, where on 19.3.20 no new cases of positivity were recorded for the first time) with the Italian experience of lockdown progressive (and not as rigorous) in Northern Italy. To confirm that isolation is the only truly effective strategy. (14)
The incubation period of Covid-19 - according to another very recent study based on the observation of 2015 cases (including 99 children) in 28 Provinces of China - is more than the 14 days indicated so far by the WHO (or WHO, World Health Organization). In 233 cases out of 2015. Up to 33 days in some cases. Chinese researchers therefore recommend extending the minimum isolation period to 18, or even better to 21 days. (15)
Dario Dongo
Footnotes
(1) Institute of Medicine. Reusability of facemasks during an influenza pandemic: facing the flu. National Academy of Sciences, 2006. www.nap.edu/openbook.php?record_id=11637.
Association for Professionals in Infection Control and Epidemiology (APIC). APIC position paper: extending the use and / or reusing respiratory protection in healthcare settings during disasters 2009.
(2) Institute of Medicine (IOM) National Academy of Sciences. (2010 update). Preventing transmission of pandemic influenza and other viral respiratory diseases: personal protective equipment for healthcare personnel. National Academies Press, 2010. ISBN-13: 978-0-309-16254-8 https://www.ncbi.nlm.nih.gov/books/NBK209584/
Siegel JD, Rhinehart E, Jackson M, Chiarello L. (2007). Guideline for isolation precautions: preventing transmission of infectious agents in health care settings. Am J Infect Control 2007; 35 (10 suppl 2): S65-164 https://www.ncbi.nlm.nih.gov/pubmed/18068815
(3) Xi He, Eric HY Lau, Peng Wu, Xilong Deng, Jian Wang, Xinxin Hao, Yiu Chung Lau, Jessica Y Wong, Yujuan Guan, Xinghua Tan, Xiaoneng Mo, Yanqing Chen, Baolin Liao, Weilie Chen, Fengyu Hu , Qing Zhang, Mingqiu Zhong, Yanrong Wu, Lingzhai Zhao, Fuchun Zhang, Benjamin J Cowling, Fang Li, Gabriel M Leung. (2020). Temporal dynamics in viral shedding and transmissibility of COVID-19. MedRxiv (study awaiting peer review). doi: https://doi.org10.1101/2020.03.15.20036707
(4) Johnson DF, Druce JD, Birch C, Grayson ML. (2009). A quantitative assessment of the efficacy of surgical and N95 masks to filter influenza virus in patients with acute influenza infection. Clin Infect Dis 2009; 49: 275-7 https://www.ncbi.nlm.nih.gov/pubmed/19522650
(5) Milton DK, Fabian MP, Cowling BJ, Grantham ML, McDevitt JJ. (2013). Influenza virus aerosols in human exhaled breath: particle size, culture, and effect of surgical masks. PLoS Pathogens 2013; 9: e1003205. https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1003205
(6) Chen YC, Chen PJ, Chang SC, Kao CL, Wang SH, Wang LH, et al. (2004). Infection control and SARS transmission among healthcare workers, Taiwan. Emerg Infect Dis 2004; 10 (5): 895-898. doi: 10.3201 / eid1005.030777 https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3323237/
(7) Lo JY, Tsang TH, Leung YH, Yeung EY, Wu T, Lim WW. Respiratory infections during SARS outbreak, Hong Kong, 2003. Emerg Infect Dis 2005; 11: 1738-41 https://www.ncbi.nlm.nih.gov/pubmed/16318726
(8)Center for Disease Control and Prevention. (2009). Interim recommendations for facemask and respirator use to reduce 2009 influenza A (H1N1) virus transmission. www.cdc.gov/h1n1flu/masks.htm
(9) Bell D, Nicoll A, Fukuda K, Horby P, Monto A, Hayden F, et al. (2006) Non-pharmaceutical interventions for pandemic influenza, national and community measures. Emerg Infect Dis 2006; 12: 88-94 https://dx.doi.org/10.3201/eid1201.051371
(10) WHO (2020). Use of masks (to reduce the risk of transmission of the COVID-19 virus). Recommendations, https://www.who.int/emergencies/diseases/novel-coronavirus-2019/advice-for-public/when-and-how-to-use-masks
WHO recommends the use of masks only in specific conditions (eg cough, fever and breathing difficulties). However, ignoring the risks of transmission in presymptomatic or asymptomatic phases, already ascertained in the Covid-19 pandemic (!)
(11) MacIntyre CR, Wang Q, Rahman B, Seale H, Ridda I, Gao Z, et al. Efficacy of face masks and respirators in preventing upper respiratory tract bacterial colonization and co-infection in hospital healthcare workers. Prevent Med 2014; 62: 1-7. https://doi.org/10.1016/j.ypmed.2014.01.015
(12) TNT masks - COVID-19 epidemiological emergency information. Circular Min. Sal.13.3.20 http://www.trovanorme.salute.gov.it/norme/renderNormsanPdf?anno=2020&codLeg=73665&parte=1%20&serie=null
(13) DECREE-LAW 2 March 2020, n. 9. Urgent support measures for families, workers and businesses connected to the epidemiological emergency from COVID-19. See article 34, su https://www.iss.it/documents/20126/0/DECRETO-LEGGE+2+marzo+2020%2C+n.+9.pdf/997f707f-6c8f-530c-e82f-589824935cbb?t=1584545708698
(14) Marek Kochanczyk, Frederic Grabowski, Tomasz Lipniacki. (2020). Impact of the contact and exclusion rates on the spread of COVID-19 pandemic. MedRxiv (study pending peer-review). doi: https://doi.org/10.1101/2020.03.13.20035485
(15) Xue Jiang, Yawei Niu, Xiong Li, Lin Li, Wenxiang Cai, Yucan Chen, Bo Liao, Edwin Wang. (2020). Is a 14-day quarantine period optimal for effectively controlling coronavirus disease 2019 (COVID-19)? MedRxiv (study pending peer-review). doi: https://doi.org10.1101/2020.03.15.20036533
Dario Dongo, lawyer and journalist, PhD in international food law, founder of WIISE (FARE - GIFT - Food Times) and Égalité.
