The rapid global spread of SARS-CoV-2 and the resulting coronavirus disease (COVID-19) pandemic has led to urgent efforts to contain and mitigate transmission, leading to significant and widespread socioeconomic disruption. As of April 3rd 2020, over one million cases have been reported worldwide, as well as over 60,000 deaths, with ongoing spread in most parts of the world.
While COVID-19 infection can cause severe and life-threatening illness in the immunocompromised and the elderly, with a case fatality ratio of over 10% in the latter group, it is frequently asymptomatic, or associated with only mild symptoms in many people. In this sense, the rapid spread of the virus has raised concerns that healthcare systems lack sufficient resources and will be unable to bear the burden of accommodating patients suffering from COVID-19, resulting in significantly increased morbidity and mortality.
In order to avoid overwhelming national healthcare resources and mitigate the burden of infection, many countries have imposed both international and domestic travel restrictions, closed schools and non-essential businesses, and strictly limited public gatherings. Such measures are designed to minimize person-to-person exposures, reducing the effective reproduction number (R0), and thus the growth rate of the epidemic.
Besides, behavior such as social distancing, self-isolation while symptomatic, handwashing, disinfecting surfaces and hygienic etiquette around coughing and sneezing can further mitigate transmission on an individual level. Interventions such as these can offer protection (reduction in risk of infection) to susceptible individuals, and/or containment (reduction in risk of onward transmission) to infected individuals.
Furthermore, the use of face masks is also being evaluated as a mandatory measure.
Although personal protection is a leading motivator for mask wearing, it is generally thought that face masks are more effective in providing containment, limiting onward transmission from infectious carriers. In this way, surgical masks ―loose-fitting, disposable devices that creates a physical barrier on the mouth and nose of the wearer―, offer a barrier from the inside to the outside, that is, they prevent us from dispersing part of the small drops that we produce when speaking or coughing, at short distances. Nevertheless, even if surgical masks offer limited personal protection, a general recommendation to wear these masks in public may be particularly beneficial by containing transmission from unknowingly infectious persons.
On the other hand, N95 masks are protective devices designed to achieve a very close facial fit and very efficient filtration of airborne particles ―the N95 designation means that when subjected to careful testing, the respirator blocks at least 95% of very small (0.3 micron) test particles. However, since N95 masks are critical supplies that must continue to be reserved for health care workers and other medical first responders, the Centers for Disease Control and Prevention (CDC) does not recommend that the general public wear N95 masks to protect themselves from respiratory diseases, including coronavirus (COVID-19). N95 respirators are considered functionally equivalent to certain respirators regulated under non-U.S. jurisdictions, such as FFP2 or FFP3 respirators of the European Union and KN95 respirators of China.
In sumary, both surgical and N95 masks limitand redirect the projection of airborne droplets. However, only N95 masks provide a deeper protection for viral aerosol shedding and coronavirus.
Editorial Disclaimer: information published during the 2020 COVID-19 pandemic may be updated frequently to reflect the dynamic nature of current understanding.