What do hair stylists, hamsters, and cruise ship passengers have in common? All three provide evidence supporting the use of face masks.
In May 2020, two hair stylists working at Great Clips in Missouri came into close contact with 139 clients while unknowingly infected with COVID-19. Due to a City of Springfield ordinance mandating face masks, both wore double-layered cotton coverings. After testing positive on day 8 and 10 respectively, the salon was closed for deep cleaning. After 2 weeks of contact tracing, no COVID-19 symptoms were identified among the exposed clients or their secondary contacts. All tested negative for COVID-19.
Face masks serve to block the droplets emitted when we breathe–which are approximately 0.5 – 10 micromoles in size–as well as the larger droplets leaving our noses and mouths when we cough or sneeze. N95 respirators are designed to capture 99% of the particles over 0.3 micromoles and 85% under that size. Surgical masks have been shown to filter out 99% of the particles over 0.3 micromoles and 76% below that size. And recent studies show double-layered 600-thread count cotton filters 99% and 82% of those same-sized particles.
In diseases with airborne or droplet spread, studies show face masks reduce “non-contact transmission.” Researchers at the University of Hong Kong conducted an experiment on Syrian hamsters, who experience weight loss, rapid breathing, and lethargy when infected with SARS-CoV-2. To establish likelihood of transmission, a group of infected and healthy hamsters were placed next to each other in cages and after 4 days, 67% became infected. Then, researchers placed a surgical mask barrier between the cages, as if the “healthy” hamsters were wearing face masks. The transmission rate dropped by half; only 33% of the hamsters tested positive for SARS-CoV-2. Next, researchers turned the mask barrier around, so the “sick” hamsters were wearing face masks, theoretically “reducing” exhalation of infected respiratory droplets. Transmission dropped further; just 16.7% tested positive for SARS-CoV-2.
Emerging research reveals face masks may also reduce disease severity and mortality through a “dose-response relationship,” whereas, a lower viral load—the number of viral particles to which one is exposed—causes milder symptoms. To look at this another way: As mask-wearing increases in a given population, more infections should be “asymptomatic” (testing positive without being sick) in that group.
Comparing the passengers of two ill-fated sea voyages demonstrates something remarkable.
The Diamond Princess cruise ship departed from the Port of Yokohama, Japan on January 20, 2020 for a round-trip tour of Southeast Asia, carrying 2,666 passengers and 1,045 crew. The source of infection was later identified as an 80-year old male who had symptoms prior to boarding. When he tested positive for COVID-19 on February 1, the ship was immediately notified. However, passengers were not informed. The ship continued operating normally over the next few days, keeping the fitness clubs, theatres, casinos, bars, and buffet-style restaurants open. By February 4, passengers began isolation in their rooms and the ship entered a 14-day quarantine based on WHO guidelines. In the end, 712 of 3,711 passengers and crew became infected and 14 passengers died (a mortality rate of 2.0%.) About 17.9% had asymptomatic infections.
On a different continent, just three days after the WHO declared a worldwide pandemic, the luxurious ocean liner Greg Mortimer set sail from Ushuaia, Argentina on March 15 for a 21-day cruise following the path of Antarctic explorer Ernest Shackleton. (Doesn’t this sound like the trip of a lifetime?) Prior to boarding, all 128 passengers and 95 crew passed symptom and temperature screening. The first recorded fever occurred on day 8. All passengers were immediately confined to their cabins and issued surgical masks. Crew members, wearing N95 masks, delivered meals to cabin doors three times daily, but did not service the rooms. Ultimately, 128 (59%) of 217 on board tested positive for COVID-19. An astounding 81% who tested positive were asymptomatic. Of those with symptoms, 16 were mild, 8 required evacuation, and 1 patient died (mortality rate of 0.8%.)
While we cannot be certain why the mortality rate was 60% lower for the Greg Mortimer than the Diamond Princess, it seems unrelated to age. Aurora Expeditions reported the average age of cruisers on the Greg Mortimer was 63 and the average age of passengers on the Diamond Princess was 58. In my opinion, understanding why passengers of one ship did better than the other may be the most important question of all.
Whether we like it or not, the face mask—an N95, surgical mask, or one made of cotton cloth—has become the universal symbol of 2020. And it is possible that face masks save more lives than we realize. The Syrian hamsters who contracted COVID-19 while “wearing” surgical masks became less ill than those who became infected without a mask barrier in place. And the same could be said for the cruise ship passengers. Now, if we could only get the whole nation on board…..