Masks in Schools Reduce COVID Transmission
ViralThought, by Jeffrey Kocher MD Public Health officials in some locations are under tremendous pressure right now to end school mask mandates. This is likely a confluence of pandemic fatigue, venting of pent up frustration, and a sense of impatience with the finish line appearing within view. Unfortunately this push to end school mask requirements is coinciding with the surge of Omicron variant cases and the most rapid spread of Covid-19 disease that we have endured since the start of the pandemic. The following are a number of themes which appear repeatedly in lay press articles influencing people’s opinions about masks in school, and I have attempted to point out some of the fallacies they contain.
“There is no proof that masks help prevent spread of Covid-19 in schools.” It’s always difficult to prove that emergency Public Health orders are effective because they are issued during a crisis and are not supported by randomized controlled trials. Opponents will always say the intervention didn’t make a difference when X number of people become infected despite the intervention. When it’s pointed out that in another venue, which did not adopt the measure more cases occurred, the usual response is that there are differences in the two locations that render comparison meaningless.
“You are not going to prevent children from getting Covid-19 by wearing masks in school, they will just catch it in the community”. The goal of masks in schools was never (or shouldn’t have ever been) to prevent a certain number of children in a given community from becoming infected. The goal was to prevent outbreaks of clustered infection in schools leading to classroom or school closures. Right now at this moment, while there is a growing chorus to end masks in schools, some school districts around the country are scrambling to enact mask mandates in an attempt to prevent just such closures. Given the increased ability of Omicron to sneak through prior antibody defenses and cause infection in many people with vaccine or natural immunity, masks have become if anything, more important to get us through the Omicron wave without having to revert to remote learning.
“The CDC was wrong, cloth masks and surgical masks don’t prevent infection, only N95 or KN95 masks do that”. Let’s review some basic principles which address this objection. It would have been helpful for the CDC to provide this kind of discussion when they recently changed their mask guidance. The SARS-2-Cov19 virus is spread almost entirely via the respiratory route, and there are two main ways this happens. The first, and numerically more important, is near field transmission. This occurs when the susceptible individual is within the expelled breath cone of respiratory secretion particles emitted by the infected person. These droplets are expelled in greater or lessor amounts by breathing, speaking, yelling and singing, and are a basic fact of human physiology. The second mode of transmission evolves microscopic droplets which are small enough to be suspended in air currents for many minutes, and can be inhaled and cause infection at greater distances than near field transmission. Good evidence shows many more infections are caused by the first scenario. Masks, even less effective ones, are quite capable of reducing the exposure of the susceptible person. They accomplish this by a combination of reducing the number of droplets emitted and directing the breath cone away from the person in front of the infected individual. Detailed experiments reported recently in the Proceedings of the National Academy of Sciences demonstrate this very nicely. Maximal protection is afforded when both members of the pair wear masks, but there is very significant protection when only the infected person is masked, and a lesser but still important reduction when only the susceptible is masked. This series of very sophisticated experiments in near field transmission show that even simple surgical or procedure masks dramatically reduce the exposure of the susceptible individual to the droplets being sprayed in their direction. It is true that higher quality masks such as N95 or KN95 are needed to substantially reduce exposure to aerosolized droplets. Fewer infections are caused by this mode of distant infection, and this is where improved ventilation, fresh air exchange and effective HEPA air filtration become extremely important. Masks are part of a layered mitigation strategy, they were never intended to be the entire solution but are are an important contribution. Recent data from North Carolina school districts with different social distancing requirements show that when kids are wearing masks, yes the regular, any kind you like, masks, there is the same low rate of disease transmission whether they required 6ft, 3ft, or no amount of social distancing. The ability of masks to eliminate the need for social distancing makes it possible to keep schools open and importantly allows the children to be close to their peers. This is real world validation of the laboratory results proving masks are important in blocking near field transmission. The whole pandemic has been a learning experience for everyone, including the CDC. To take the approach that since the CDC may have been wrong about something earlier in the pandemic we can never trust what they say now, is infantile. To the religious I would say, “the Christian Church maintained the earth was the center of the solar system and burned people at the stake for insisting this wasn’t true”. To the non-believers I say, “Here’s the paper that proves my point about mask effectiveness, don’t blame me if you can’t read and interpret it for yourself.” As soon as you are forced to rely on someone else to do that you are subject to their personal biases.”
The “I want proof, but I don’t have to provide any paradox.” People who are zealously against masks in school usually demand “proof”, frequently in the form of randomized controlled trials, that masks work. They offer all sorts of speculation about their perceived ill effects from mask wearing. Of course, they feel exempt from having to provide any scientific evidence that any of their claims are true. There is no validated evidence that masks cause any significant problems for otherwise healthy children who are deemed not to have any medical contraindications. When the anti-mask crowd present their “evidence”, it is always in the form of opinion pieces, which are never backed up by anything more substantial than: we believe, experts think, anyone can see, it must be, or it is highly likely. The only thing we know for sure backed up by real world data is that children are harmed by school closings and the lack of in person instruction and contact with their peers.
“Children don’t really get sick from COVID and it’s not fair to mask them to protect older people”. Statistically it is true that healthy children are much less likely to suffer severe disease or death, but to date close to 1000 children in the US have died from COVID and many thousands have been hospitalized. During the current month of January 2022, we have seen the highest number of children admitted to the hospital with a primary diagnosis of COVID since the beginning of the pandemic. Last month in New Jersey, four children died from COVID and three of these were infants. State level data from around the country shows that 1.7 - 4.4% of hospitalizations where the leading diagnosis is COVID have occurred in children. It would seem to be a reasonable goal to reduce the number of children bringing the infection home to vulnerable family members, who either can’t be vaccinated or may not respond to vaccine. The notion of putting up with an inconvenience for the sake of family and loved ones does not seem an unreasonable burden.
“Everyone is destined to get Omicron and we may as well just let it happen now.”This is highly unlikely to be an accurate statement. The Omicron surge is beginning to rapidly recede in the areas of the country which were affected first, and it has not infected everyone there. Areas hard hit by the Omicron surge so far have seen their hospitals, schools and other critical services teeter on the brink of ceasing to function in an acceptable way, and several states have been forced to adopt crisis standards of care. Removing masks from children at this precise inflection point in the pandemic is perhaps the worst possible time to do this. The scientific laboratory evidence and the epidemiological evidence is clear that masks help to prevent the spread of the virus as part of a layered protection plan in schools. This is the wrong time to remove a proven mitigation method. People advocating unmasking in schools have failed to produce any scientifically validated evidence that they cause harm and their arguments are based solely on opinion. Data from around the world is highly suggestive that the Omicron wave will recede rapidly and national data shows it has already peaked for the country as a whole, even as it tears through some regions. This is a time to be be patient, for a short interval and continue to rely on a proven mitigation strategy.