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With COVID, flu and RSV circulating, it’s time to follow the evidence: Return to mask mandates

In 2020, with adult ICUs at risk of being overwhelmed, we wore masks and accepted restrictions. Now pediatric intensive care is at risk. Will leaders follow…



Ontario Premier Doug Ford and Health Minister Sylvia Jones in conversation at Queen's Park, the day after Ontario’s chief medical officer of health ‘strongly recommended’ mask wearing. THE CANADIAN PRESS/Chris Young

The number of children and babies with respiratory illnesses currently exceeds the capacity of our health system to care for them. More adult Canadians will die directly of COVID-19 this year than died last year or in 2020.

Bar graph showing deaths from COVID in Canada
COVID deaths in 2022 outnumber those in 2020 or 2021. (Bill Comeau)

Eight per cent of vaccinated people with COVID infections that don’t require hospitalization end up with long COVID, with each subsequent infection repeating the risk. COVID increases the risk of cardiovascular and other health problems, enough to cause a stark rise in excess deaths and to shorten life expectancy.

In 2020, when adult intensive care units were at risk of being overwhelmed, we wore masks and accepted restrictions. With pediatric intensive care now at risk, will leaders follow the evidence and tell us to mask up? While federal officials and several provinces are now recommending masks in all indoor public settings — although Ontario’s Chief Medical Officer of Health Kieran Moore was seen without one at a partythere are no returns to mandates for the public yet.

Wear the best mask available

We now know that masks prevent the spread of respiratory diseases; some better than others.

A young woman wearing a white face masks with overhead ties
A Vitacore CaN99 respirator with overhead elastic; N95s, CaN99 and FFP3 typically provide greater than 90 per cent filtration without formal fit testing. (Gurleen Dulai, Ranmeet Dulai), Author provided

The most effective masks, and the only ones recognized as respiratory protection by formal standards, are respirator masks: N95s, CaN99s, FFP3s and reusable elastomeric respirators. In workplaces, respirators are fit-tested to the individual, resulting in greater than 99 per cent protection.

Even without fit testing, respirator masks prevent more than 90 per cent of particles smaller than one micron from reaching the wearer (submicron particles, the smallest among those thought to be relevant).

Respirator masks are relatively expensive — typically a few dollars each — but thanks to Canadian manufacturers, they are available and there are no longer concerns about supply chains for front-line workers. They can be safely reused, with good retention of their filtration. New designs are comfortable and fit most faces.

A young woman wearing a black face mask with ear loops
A KN95/KF94 mask with ear loops typically provides about 70 per cent filtration. (Gurleen Dulai, Ranmeet Dulai), Author provided

N95s are secured with overhead attachments, providing a good seal at the edges. KN95s and KF94s have excellent filtration material, but their ear loops do not provide as secure a seal, and their filtration is around 70 per cent. A certified medical mask with a well-fitted cloth mask over it, preferably with overhead ties, provides comparable filtration at lower cost.

A young woman wearing a cloth face mask over a surgical mask
A well-fitting cloth mask over a certified medical mask typically produces about 70 per cent filtration. (Gurleen Dulai, Ranmeet Dulai), Author provided

Certified Level 1 medical masks alone do not fit well, which affects their filtration ability because unfiltered air passes around the edges with every breath. In tests on humans, these have typically filtered at around 50 per cent, similar to well-designed two-layer cotton cloth masks, ideally with overhead ties; both are around 50 per cent.

Poorly fitting cloth masks and non-certified procedure masks are likely worse than 50 per cent, but better than nothing. The World Health Organization advises: “Make wearing a mask a normal part of being around other people,” to which we would add: wear the best mask available.

A young woman wearing a blue surgical face mask
A Level 1 certified mask provides filtration around 50 per cent because of visible gaps and poor fit. To test fit, breathe out rapidly and feel for air leaks around the mask with your hands. (Gurleen Dulai, Ranmeet Dulai), Author provided

The filtration data above are mirrored by epidemiologic data showing that protection correlates with mask type. In studies of source control (prevention of contamination of the air by respiratory particles), the same hierarchy of efficiency is seen, with N95s at the top. N95s with exhalation valves are an exception and should not be used to prevent spread of respiratory diseases.

Masks protect against COVID-19 and other respiratory infections. They are also an ideal tool to counter COVID variants, as well as RSV and influenza. Working on basic physical principles — impaction, sedimentation and diffusion — they protect regardless of the variant or strain.

Staying home when sick is helpful, but many people are infectious before they have symptoms, or never have symptoms. Wearing a mask to prevent infected particles from reaching the environment is basic pollution management: control is best at the source.

Wearing a mask to protect the individual, once controversial, is now settled by filtration science and epidemiology. The impact of mask mandates in countries where spontaneous mask wearing was low was repeatedly demonstrated, proving that masks protect us all.

Why people aren’t wearing masks

Why aren’t people wearing masks? Some remember the inconsistency of the advice early in the pandemic. Masks may be conflated with closures and capacity restrictions and the resulting hardships. Whatever the reason — stigma, peer pressure or concern about virtue signalling — countries outside Asia do not have a mask-wearing culture.

Infographic summarizing the literature on filtration properties of respirators and masks.
Infographic summarizing the literature on filtration properties of respirators and masks. (Shiblul Hasan), Author provided

Under these circumstances, it will likely take more than strong recommendations to achieve the high uptake of mask use that will be most effective in reducing transmission of respiratory viruses. Masks protect individuals, imperfectly. Mask mandates (or high voluntary use of masks) protect populations.

Bringing back mask mandates with unequivocal signalling from governments about the effectiveness of both masks and mask mandates would be the best immediate response to our current crisis. Confidence that mask-wearing is effective correlates geographically with willingness to wear a mask: in time, we hope knowledge will change culture. Strong communication from political and public health leadership would increase community understanding that the minor inconvenience of wearing a mask in public indoor spaces is justified by the death and disability prevented.

In North America, the strategy of using masks according to personal judgment has predictably failed, the strategy of strongly recommending masks is unproven, and it’s too late to experiment. Mask mandates, however, are backed by strong evidence of effectiveness in both Canada and the United States.

Mask mandates are less damaging to a recovering economy than physical distancing and capacity limits, and less damaging to learning than a return to remote schooling.

Two line graphs showing relationship between school openings, mask use and community COVID 19 cases and deaths
The relationship between mode of school opening (remote, hybrid and in-person) and mask use at school with community cases and deaths, based on county-level data in the U.S. (Chernozhukov et al, PNAS 2021:118;e2103420118), CC BY

Schools and universities represent a particularly important opportunity. COVID spreads between children in schools to infect the whole population; this is mitigated by mask wearing. After Massachusetts lifted its mask mandate, school boards did so at different times, creating a natural experiment: transmission was higher among students and staff where mandates were lifted compared with where they were still in place.

There is no convincing evidence to date that masks reduce social or language skills. Decreasing spread in schools would increase learning by reducing student and teacher sick days and preserving in-person instruction. Keeping children in schools keeps parents at work.

Mask mandates will not produce a rapid fix of our current problems with respiratory viruses. Indicators will lag by weeks. Until we have a whole-of-society approach that recognizes that COVID is airborne, mask mandates offer us the best immediate opportunity to preserve our health-care system, mitigate death and disability from respiratory viruses, support the economy and safely maintain social contacts in our private lives.

Rebecca Rudman, co-founder of the Windsor Essex Sewing Force and member of McMaster’s Cloth Mask Knowledge Exchange, co-authored this article.

Catherine Clase is editor-in-chief of and a member of the Cloth Mask Knowledge Exchange, a research and knowledge translation group that includes industry stakeholders. Industry stakeholders contribute to the Cloth Mask Knowledge Exchange by contributing to grant funding, and through in-kind contributions of time and expertise. Industry stakeholders make masks and distribute polypropylene and other fabrics. They may potentially benefit from this article. She is a member of McMaster's Centre of Excellence in Protective Equipment and Materials. Catherine has received consultation, advisory board membership or research funding from the Ontario Ministry of Health, Sanofi, Pfizer, Leo Pharma, Astellas, Janssen, Amgen, Boehringer-Ingelheim and Baxter. In 2018 she co-chaired a KDIGO potassium controversies conference sponsored at arm's length by Fresenius Medical Care, AstraZeneca, Vifor Fresenius Medical Care, Relypsa, Bayer HealthCare and Boehringer Ingelheim. Catherine Clase receives funding from CIHR, and is a member of the Green Party, the American Society of Nephrology, the Canadian Society of Nephrology, the American Association of Textile Chemists and Colorists and ASTM International.

Charles-Francois de Lannoy receives funding from the Natural Sciences and Engineering Research Council (NSERC) of Canada, the Global Water Futures (GWF) Research organization, Ontario Centres of Excellence (OCE), Federal Economic Development Agency for Southern Ontario (FedDev), Canadian Foundation for Innovation (CFI), the French Embassy, and McMaster University. He has received funding in partnership with Pall Water, Trojan Technologies, Hatch Ltd., and PW Fabrication. He has engaged in various research projects and testing/validation of facemasks for several private companies in Ontario. He is affiliated with the Cloth Mask Knowledge Exchange as an expert advisor.

Ken G. Drouillard receives funding from Natural Sciences and Engineering Research Council (NSERC) of Canada, Environment and Climate Change Canada, Ontario Ministry of Environment, Conservation and Parks and Mitacs. He is affiliated with the WE-Spark Health Institute, Detroit River Canadian Cleanup Committee, International Association of Great Lakes Research, Editor of Bulletin of Environmental Contamination and Toxicology and science advisor for Windsor-Essex Sewing Force.

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FDA advisory committee votes unanimously in favor of a one-shot COVID-19 vaccine approach – 5 questions answered

Many questions remain about next steps for US vaccine policy. But the FDA advisory panel’s hearty endorsement of a single-composition COVID-19 vaccine…



The FDA advisory committee discussed vaccine safety, effectiveness of the current shots, potential seasonality of COVID-19 and more. wildpixel/iStock via Getty Images Plus

The U.S. Food and Drug Administration’s key science advisory panel, the Vaccines and Related Biological Products Advisory Committee, met on Jan. 26, 2023, to chart a path forward for COVID-19 vaccine policy. During the all-day meeting, the 21-member committee discussed an array of weighty issues including the efficacy of existing vaccines, the composition of future vaccine strains and the need to match them to the circulating variants of SARS-CoV-2, the possibility of moving to an annual-shot model, the potential seasonality of the virus and much more.

But the key question at hand, and the only formal question that was voted on, following a proposal from the FDA earlier in the week, had to do with how to simplify the path to getting people vaccinated.

The Conversation asked immunologist Matthew Woodruff, who has been on the front lines of studying immune responses to COVID-19 since the early days of the pandemic, to walk us through the big questions of the day and what they mean for future COVID-19 vaccine strategies.

What exactly did the advisory committee vote on?

The question put before the committee for a vote was whether to move to one COVID-19 vaccine consisting of a single composition for all people – whether currently vaccinated or not – and away from the current model that includes one formulation given as a primary series and a separate formulation administered as a booster. Importantly, approved formulations could come from any number of vaccine manufacturers, not just those that have currently authorized vaccines.

The U.S. Centers for Disease Control and Prevention currently requires that the primary series of shots, or the first two doses of the vaccine that a patient receives, consist of the first generation of vaccine against the original strain of SARS-CoV-2, known as the “Wuhan” strain of the virus. These shots are given weeks apart, followed months later by a booster shot that was updated in August 2022 to contain a bivalent formulation of vaccine that targets both the original viral strain and newer subvariants of omicron.

The committee’s endorsement simplifies those recommendations. In a 21-to-0 vote, the advisory board recommended fully replacing, or “harmonizing,” the original formulation of the vaccine with a single shot that would consist of – at least for now – the current bivalent vaccine.

In doing so, it has signaled its belief that these new second-generation vaccines are an upgrade over their predecessors in protecting from infection and severe illness at this point in the pandemic.

If the FDA panel’s recommendation is endorsed by the CDC, only a single composition of vaccine – in this case, the updated bivalent shot – will be used for both vaccinated and unvaccinated people.

Will the single shot remain a mixed-strain, or bivalent, vaccine?

For now, the single shot will be bivalent. But this may not always be the case.

There was a general agreement that the current bivalent shot is preferable to the original vaccine targeted at the Wuhan strain of the virus by itself. But committee members debated whether that original Wuhan vaccine strain should continue to be a part of updated vaccine formulations.

There is no current data comparing a monovalent, or single-strain, vaccine that targets omicron and its subvariants against the current bivalent shot. As a result, it’s unclear how a monovalent shot against recent omicron subvariants would perform in comparison to the bivalent version.

What is immune imprinting, and how does it apply here?

A main reason for the debate over monovalent versus bivalent – or, for that matter, trivalent or tetravalent – vaccines is a lack of understanding around how best to sharpen an immune response to a slightly altered threat. This has long been a debate surrounding annual influenza vaccination strategies, where studies have shown that the immune “memory” that forms in response to a prior vaccine can actively repress a robust immune response to the next.

This phenomenon of immune imprinting, originally coined in 1960 as “original antigenic sin,” has been a topic of debate both within the advisory committee and within the broader immunological community.

Although innovative strategies are being developed to overcome potential problems with routinely updated vaccines, they are not yet ready to be tested in humans. In the meantime, it is unclear how bivalent versus monovalent vaccine choices might alter this phenomenon, and it is very clear that more study is needed.

Is the committee considering only mRNA vaccines?

While a significant portion of the discussion focused on the mRNA vaccine platform used by both Pfizer and Moderna, several committee members emphasized the need for new technologies that could provide broader immunological protection. Dr. Pamela McInnes, a now-retired longtime deputy director of the National Center for Advancing Translational Sciences, highlighted this point, saying, “I would make a plea for ongoing research on broader protection, maybe different platforms, maybe a different approach.”

A good deal of attention was also directed toward Novavax, a protein-based formulation that relies on a more traditional approach to vaccination than the mRNA-based vaccines. Although the Novavax vaccine has been authorized by the FDA for use since July 2022, it has received much less national attention – largely because of its latecomer status. Nonetheless, Novavax has boasted efficacy rates on par with its mRNA cousins, with good safety profiles and less demanding long-term storage requirements than the mRNA shots.

By simplifying the vaccine schedule to include only a single vaccine formulation, the committee reasoned, it might be easier for competing vaccination platforms to break into the market. In other words, newer vaccine contenders would not have to rely on patients’ having already received their primary series before using their products. Companies seemed ready to take advantage of that future flexibility, with researchers from Pfizer, Moderna and Novavax all revealing their companies’ exploration of a hybrid COVID-19 and flu shot at various stages of clinical trials and testing.

Would the single shot resemble flu vaccine development?

Not necessarily. Currently, the influenza vaccine is decided by committee through the World Health Organization. Because of its seasonal nature, the strains to be included in each season’s flu vaccine strain for the Southern and Northern hemispheres, with their opposing winters, are selected independently. The Northern Hemisphere’s selection is made in February for the following winter based on a vast network of flu monitoring stations around the globe.

Although there was broad consensus among panelists that the shots against SARS-CoV-2 should be updated regularly to more closely match the most current circulating viral strain, there was less agreement on how frequent that would be.

For instance, rapidly mutating strains of the virus in both summer and winter surges might necessitate two updated shots a year instead of just one. As Dr. Eric Rubin, an infectious disease expert from the Harvard T.H. Chan School of Public Health, noted, “It’s hard to say that it’s going to be annual at this point.”

Matthew Woodruff receives funding from the National Institute of Health and the US Department of Defense to support his academic research.

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Measles virus ‘cooperates’ with itself to cause fatal encephalitis

Fukuoka, Japan—Researchers in Japan have uncovered the mechanism for how the measles virus can cause subacute sclerosing panencephalitis, or SSPE, a…



Fukuoka, Japan—Researchers in Japan have uncovered the mechanism for how the measles virus can cause subacute sclerosing panencephalitis, or SSPE, a rare but fatal neurological disorder that can occur several years after a measles infection.

Credit: Kyushu University/Hidetaka Harada/Yuta Shirogane

Fukuoka, Japan—Researchers in Japan have uncovered the mechanism for how the measles virus can cause subacute sclerosing panencephalitis, or SSPE, a rare but fatal neurological disorder that can occur several years after a measles infection.

Although the normal form of the measles virus cannot infect the nervous system, the team found that viruses that persist in the body can develop mutations in a key protein that controls how they infect cells. The mutated proteins can interact with its normal form, making it capable of infecting the brain. Their findings were reported in the journal Science Advances.

If you are of a certain age, you may have gotten the measles as a child. Many born after the 1970s have never gotten it thanks to vaccines. The condition is caused by the virus of the same name, which is one of the most contagious pathogens to this day. The World Health Organization estimates that nearly nine million people worldwide were infected with measles in 2021, with the number of deaths reaching 128,000.

“Despite its availability, the recent COVID-19 pandemic has set back vaccinations, especially in the Global South,” explains Yuta Shirogane, Assistant Professor at Kyushu University’s Faculty of Medical Sciences. “SSPE is a rare but fatal condition caused by the measles virus. However, the normal measles virus does not have the ability to propagate in the brain, and thus it is unclear how it causes encephalitis.”

A virus infects cells through a series of proteins that protrude from its surface. Usually, one protein will first facilitate the virus to attach to a cell’s surface, then another surface protein will cause a reaction that lets the virus into the cell, leading to an infection. Therefore, what a virus can or cannot infect can depend heavily on the type of cell.

“Usually, the measles virus only infects your immune and epithelial cells, causing the fever and rash,” continues Shirogane. “Therefore, in patients with SSPE, the measles virus must have remained in their body and mutated, then gained the ability to infect nerve cells. RNA viruses like measles mutate and evolve at very high rates, but the mechanism of how it evolved to infect neurons has been a mystery.”

The key player in allowing the measles virus to infect a cell is a protein called fusion protein, or F protein. In the team’s previous studies, they showed that certain mutations in the F protein puts it in a ‘hyperfusongenic’ state, allowing it to fuse onto neural synapses and infect the brain.

In their latest study, the team analyzed the genome of the measles virus from SSPE patients and found that various mutations had accumulated in their F protein. Interestingly, certain mutations would increase infection activity while others actually decreased it.

“This was surprising to see, but we found an explanation. When the virus infects a neuron, it infects it through ‘en bloc transmission,’ where multiple copies of the viral genome enter the cell,” continues Shirogane. “In this case, the genome encoding the mutant F protein is transmitted simultaneously with the genome of the normal F protein, and both proteins are likely to coexist in the infected cell.”

Based on this hypothesis, the team analyzed the fusion activity of mutant F proteins when normal F proteins were present. Their results showed that fusion activity of a mutant F protein is suppressed due to interference from the normal F proteins, but that interference is overcome by the accumulation of mutations in the F protein.

In another case, the team found that a different set of mutations in the F protein results in a completely opposite result: a reduction in fusion activity. However, to their surprise, this mutation can actually cooperate with normal F proteins to increase fusion activity. Thus, even mutant F proteins that appear to be unable to infect neurons can still infect the brain.

“It is almost counter to the ‘survival of the fittest’ model for viral propagation. In fact, this phenomenon where mutations interfere and/or cooperate with each other is called ‘Sociovirology.’ It’s still a new concept, but viruses have been observed to interact with each other like a group. It’s an exciting prospect” explains Shirogane.

The team hopes that their results will help develop therapeutics for SSPE, as well as elucidate the evolutionary mechanisms common to viruses that have similar infection mechanisms to measles such as novel coronaviruses and herpesviruses.

“There are many mysteries in the mechanisms by which viruses cause diseases. Since I was a medical student, I was interested in how the measles virus caused SSPE. I am happy that we were able to elucidate the mechanism of this disease,” concludes Shirogane.


For more information about this research, see “Collective fusion activity determines neurotropism of an en bloc transmitted enveloped virus” Yuta Shirogane, Hidetaka Harada, Yuichi Hirai, Ryuichi Takemoto, Tateki Suzuki, Takao Hashiguchi, Yusuke Yanagi,

About Kyushu University
Kyushu University is one of Japan’s leading research-oriented institutes of higher education since its founding in 1911. Home to around 19,000 students and 8,000 faculty and staff, Kyushu U’s world-class research centers cover a wide range of study areas and research fields, from the humanities and arts to engineering and medical sciences. Its multiple campuses—including the largest in Japan—are located around Fukuoka City, a coastal metropolis on the southwestern Japanese island of Kyushu that is frequently ranked among the world’s most livable cities and historically known as a gateway to Asia.

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Beloved Royal Caribbean Adult Event Still Missing; Another Returns

The cruise line has almost fully returned to normal after the covid pandemic, but one very popular activity hasn’t been brought back.



The cruise line has almost fully returned to normal after the covid pandemic, but one very popular activity hasn't been brought back.

In the early days of Royal Caribbean Group's (RCL) - Get Free Report return from its 15-month covid pandemic shutdown, cruising looked a lot different. Ships sailed with limited capacities, masks were required in most indoor areas, and social distancing was a thing.

Keeping people six feet apart made certain aspects of taking a cruise impossible. Some were made easier by the lower passenger counts. For example, all Royal Caribbean Windjammer buffets required reservations to keep the crowds down, but in practice that system was generally not needed because capacities were never reached.

Dance parties and nightclub-style events had to be held on the pool decks or in larger spaces, and shows in the big theaters left open seats between parties traveling together. In most cases, accommodations were made and events more or less happened in a sort of normal fashion.

A few very popular events were not possible, however, in an environment where keeping six feet between passengers was a goal. Two of those events -- the first night balloon drop and the adult "Crazy Quest" game show -- simply did not work with social-distancing requirements.

One of those popular events has now made its comeback while the second appears to still be missing (aside from a few one-off appearances).


Crazy Quest Is Still Mostly Missing

In late November, Royal Caribbean's adult scavenger hunt, "The Quest," (sometimes known as "Crazy Quest") began appearing on select sailings. And at the time it appeared like it was coming back across the fleet: A number of people posted about the return of the interactive adult game show in an unofficial Royal Caribbean Facebook group.

It first appeared during a Wonder of the Seas transatlantic sailing.

Since, then it's appearances continue to be spotty and it has not returned on a fleetwide basis. This might not be due to any covid-related issues directly, but covid may play a role.

On some ships, Studio B, which hosts "The Quest," has been used for show rehearsals. That has been more of an issue with the trouble Royal Caribbean has had in getting new crew members onboard. And while that staffing issue has been improving, some shows may not have had full complements of performers, so using the space for rehearsal has been a continuing need.

In addition, while covid rules have gone away, covid has not, and ill cast members may force the need for more rehearsals.

Royal Caribbean has not publicly commented on when (or whether) "The Quest" will make a full comeback

Royal Caribbean Balloon Drops Are Back   

Before the pandemic, Royal Caribbean kicked off many of its cruises with a balloon drop on the Royal Promenade. That went away because it forced people to cluster as music was performed and, at midnight, balloons fell from the ceiling.

Now, the cruise line has brought back the balloon drop, albeit with a twist. The drop itself is appearing on activity schedules for upcoming Royal Caribbean cruises. Immediately after it, however, the cruise line has added something new: "The Big Recycle Balloon Pickup."

Most of the dropped balloons get popped during the drop. Previously, crewmembers picked up the used balloons. Now, the cruise line has made it a "fun" passenger activity.

"Get environmentally friendly as you help us gather our 100% biodegradable balloons in recycle baskets," the cruise line shared in its app. 

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