The Journal of General Internal Medicine reports that there
are two likely reasons for the effectiveness of facial masks: The first—to prevent the spread of viral particles from asymptomatic individuals to others—has received a great deal of attention. However, the second theory—that reducing the inoculum of virus to which a mask-wearer is exposed will result in milder disease [italics added]...has received less attention and is the focus of our perspective which compiles virologic, epidemiologic and ecologic evidence.
Masks, depending on the material and design, filter out a majority of viral particles, but not all. The theory that exposure to a lower inoculum or dose of any virus (whether respiratory, gastrointestinal or sexually transmitted) can make subsequent illness far less likely to be severe... has been propounded for some time. Indeed, the concept of the 50% lethal dose (LD50), the virus dose at which 50% of exposed hosts die, determined via controlled experiments in which a range of exposure doses are administered to animals to calculate a dose-mortality curve, was first described in 1938. Other studies have examined the LD50—or the dose that leads to severe disease or death—for a variety of viruses in hosts or animal models.
The bottom line: Wear a mask.
I venture out about once a week. A quick trip for groceries, stuff that I wasn't able to get delivered to my door.
ReplyDeleteOver the past two months as the weather improved (marginally) I was dismayed to see mask discipline greatly fall off. On my last outing, however, almost everyone was wearing a mask.
We probably won't know until the Labour Day weekend, the end of our tourist season, how well or poorly we've fared this summer. Victoria has had a couple of outbreaks mainly connected to some of its more popular bar/lounges but the mid and north-island seem to have done better. The Lower Mainland and the Okanagan, they're another story.
I expect most of us have been watching what has happened in California and next door in Alberta and perhaps were motivated to mask-up again.
Now we're all focused on what happens in our elementary and secondary schools in the weeks ahead. You're an educator, how do you view re-opening?
Like you, Mound, we are very cautious in venturing out. We do our grocery shopping once very two weeks, and excursions to other places are limited, usually to secure more milk at Shoppers Drug Mart and the like. I have also had to go to the dentist for a dental emergency, but the protocols in place left me reasonably confident. In our area, mask use is high, having been mandated for all indoors; unlike those freedom-loving 'Muricans, our sense of the collective seems to take precedence over selfish wishes and childish impulses, for the most part.
DeleteAt times like this, I am especially glad to be retired from the classroom. That being said, if I had school-age children, I think I would send them back, despite the possibility of them contracting the virus. In Ontario, masks are being mandated in all classrooms from Grade Four onward, but my personal feeling is that they should also be used in younger grades, despite the practical problems that might pose. Some protection, even if the masks are not always going to be worn expertly by the young ones, is better than none, in my view.