Faced with the Omicron wave, the United States Centers for Disease Control and Prevention (CDC) have just change their tune and now judge the N95 mask to be the most effective, dropping cloth masks last. What regarding Quebec, when community transmission is in full swing and congested hospitals are ready, if necessary, to reduce the minimum quality of care?
Some experts say that an increase in protection is needed as soon as possible, others that the simple surgical mask still does the trick.
“The surgical mask is effective if it meets strict standards. In practice, we see that it stems infections as well as the N95 mask, “says Dr.r Stéphane Perron, medical advisor at the National Institute of Public Health of Quebec (INSPQ), an organization that maintains its support for the famous “blue mask”, both in the population and in various living and care environments.
Even if Omicron proves to be more transmissible, the INSPQ does not consider it necessary, unlike the CDC, to extend the wearing of the N95 mask in the population, including in certain more risky situations, such as when traveling by plane or when visiting crowded public places. After having opposed it for a long time, the Commission for Standards, Equity and Health and Safety at Work (CNESST) last December extended its recommendation on the wearing of the N95 mask to healthcare workers in hot and cold areas. lukewarm, or in close contact with patients.
“The take home message is that the current measures are still working. The N95 mask conforms better to the face, but if it is not tested or poorly fitted, it is no more effective than the surgical mask”, insists the Dr Perron.
“Real risk” to consider
But other experts oppose this view in the current context of high community transmission of Omicron and increasingly precarious access to care in hospitals.
“It is high time to review this position. All scientists recognize the superiority of N95, even though there are no randomized COVID studies to prove it. We are in a wave where people must protect themselves as much as possible, ”says researcher and immunologist André Veillette, of the Montreal Clinical Research Institute (IRCM). All workers at risk, including teachers and daycare workers, should have access to N95 masks, he believes. “With the return to school, there is a real risk of catching COVID in schools and daycares, during close contact with children in poorly ventilated premises. »
At a time when Quebec has just unveiled a hospitalization prioritization and management plan providing for the return of infected workers and the possible cohabitation of COVID and non-COVID patients in the hospital, André Veillette believes that all patients who visit hospitals should equip themselves with N95 during their visits. “In fact,” he said, “barring an emergency, I would even suggest that they don’t go!” »
Professor Maximilien Debia, specialist in occupational hygiene at the School of Public Health at the University of Montreal, also considers that it is time to “change the paradigm” for N95. “We have an obligation to limit the exposure of workers to the virus. If the CNESST has seen fit to extend the [port du] N95 in cold areas, we can think that this mask would also be useful for the most exposed population. It’s up to the decision-makers to see to that,” he believes.
Nuances on efficiency
The INSPQ still does not advocate the use of N95 or KN95 masks in the community, reserving it for employees exposed to increased risks of exposure, in particular during medical procedures generating aerosols. The non-compliance of several KN95 masks sold on the market adds to the reservations to limit their use by the general public. “Up to 60% of KN95 shipments do not meet standards,” says the Dr Perron.
Even surgical masks sold in stores must comply with international standards (ASTM F2100 or EN 14683), or Quebec (BNQ 1922-900), to ensure their full protection, adds this expert.
This week, the Robert-Sauvé Research Institute for Occupational Health and Safety (IRSST) issued a new notice with regard to masks, where it is stipulated that the filtration efficiency of the surgical mask oscillates between 95 to 98%, and that of the N95 between 95 to 99.9%, according to the tests. However, the N95 is considered a “respiratory protective device” (APR) because, unlike the surgical mask, it filters both exhaled and inspired air.
The filtration capacity should not be the only criterion to remember when choosing a mask, believes the IRSST. The N95 requires adjustment with each use and must be worn without a beard. The surgical mask “allows collective protection”, but not such complete respiratory protection, because of its non-sealing. The N95 is superior only if all the conditions described above are met.
For the moment, Ontario offers the N95 mask to its teachers, Italy requires it for people wanting to access certain cultural and sporting places, while it is required to enter certain businesses in Austria. “But the basic principle of prevention is to apply the principle of Swiss cheese, i.e. to multiply sanitary measures, not just to focuser on the mask,” recalls Professor Debia.
The state of health or vulnerability of people as well as the situations to which they are exposed are decisive in the choice of a mask, adds the Dr watch. “Several immunocompromised patients already carry the N95,” he insists. Whatever it is, the mask remains the main barrier measure to be respected and the one that is always maintained. 90% of the population, according to the INSPQ, followed by avoiding private gatherings (70%).
