Steps for effectively fighting an(y) airborne pathogen

Given that the COVID-19 pandemic is still upon us, now more than three years after it first appeared, with well over a million already dead and hundreds more dying every day in the US alone, it seems appropriate to devote at least the first few posts of my revitalised blog to the topic. Before turning to the specifics of this particular epidemic, I thought it useful to review the complex of public health measures which, in an ideal world, would be employed to combat any like disease.

For starters, it is important to note that we are dealing with an airborne pathogen. Simply put, infection occurs when an infected person exhales, coughs or sneezes out the pathogen, and a previously un-infected person inhales it. There is some discussion to be had over some of the specifics, for example over how long it takes for a particle carrying the infection to, in essence, fall to the ground and cease being an airborne threat, however for the purposes of this particular post the crucial point to understand is the transmission mechanism itself1. Consequently, the problem for public health authorities, to the extent they actually wish to engage in performing their stated jobs2, can be crudely distilled as follows – how do we stop “bad air” from getting into healthy lungs.

Unfortunately, we simply cannot issue every person on the planet with their own fully functional space suit and a dedicated purified air supply. Nevertheless, there do exist a number of proven measures to fight airborne pathogen transmission:

  • Mandatory universal masking. Simply put, if the infected air is filtered – twice, if everyone masks up – the probability of a pathogen getting into a healthy person’s respiratory pathways is significantly reduced. This is particularly true in the case of high-quality masks, such as medical-grade N95s, or the highly serviceable KN95s and KF94s, provided they are worn correctly and regularly changed.
  • Improved ventilation and medical-grade filtration of air in indoor spaces. This can dramatically reduce the time window for an airborne pathogen to pass from one person to another before the air volume in which it is suspended is replaced.
  • Limitations on indoor gatherings. Especially in the absence of proper ventilation and masking, these can easily turn into so-called “superspreader” events in which one or a handful of infected persons gradually expose everyone in the room to the disease.
  • Mass testing and contact tracing, coupled with mandatory quarantine for those infected. Simply put, separating the infected individuals from the general population until their illness abates has been one of the most effective public health measures throughout history.
  • Mandatory testing and possible mandatory quarantine for travellers. More than a few mass epidemics, including COVID-19, have been facilitated by travellers migrating from infected areas to uninfected ones, unknowingly carrying the disease with them. The very word “quarantine” comes from the Italian “quarantena”, or “forty days”, signifying the number of days a ship had to wait outside Venice harbour before docking to ensure that it was not carrying the plague.

Crucially, these mitigations work best when they are applied collectively, analogous to a “Swiss cheese” model of security. That is, while every individual layer of protection may have some imperfections and weaknesses, all the layers acting together dramatically reduce the likelihood of a particular security risk. The concept is just as applicable in public health as it is in information security or, really, a host of other areas, and it is telling that at the recent World Economic Forum in Davos it is precisely this “Swiss cheese” approach that was put in place to protect, quite literally, the Powers That Be3.

As well, one may note frequent usage of the word “mandatory”. This is because all these steps must necessarily apply to all members of a community or a society to be effective. If some individuals decide not to mask, not to test, or not to quarantine, they necessarily create a potential repository for the pathogen, and thus place all their other fellow citizens at risk. And, as we are dealing with the problem of an airborne disease that leaps from one person to the next, possibly even before any symptoms are made apparent, any argument rooted in some definition of “personal freedom” simply does not apply. To bring up an old saw, one’s freedom to swing one’s fists stops at the tip of another person’s nose – that is to say, no-one has a natural or inalienable right to act in a manner that harms others around them. Choosing not to follow mitigation protocols during an epidemic is not an expression of personal choice; it is pure selfishness bordering on narcissism.

Finally, a note regarding on where vaccines fit into all of this. On the whole, vaccines constitute a sort of a happy bonus. The mitigation measures outlined above, applied as a single unified solution, is still the most effective way of fighting an airborne epidemic before the population can be vaccinated, and they are the only measures to fall back upon if a vaccine against a given pathogen proves ineffectual or cannot be developed in time or at all. Simply put, adding vaccines to the list of measures above should, as a general rule, enhance the “Swiss cheese” approach, acting as an extra layer of protection. But relying on vaccines alone only works if immunity is all but guaranteed, and if the bulk of the population had already been vaccinated. To the extent both of these conditions are not met, relying on vaccines alone is not very different from simply letting the disease run through the population unabated, and hoping for the best. Which, at least in theory, is quite the opposite of what the goals of public health ought to be.


  1. There will likely be more to be said in future posts regarding the so-called “droplet theory” of COVID-19 transmission, proponents of which have spent years insisting that the virus settles on surfaces so quickly that hand-washing is far more important than wearing masks. For now, suffice it to say that ample scientific studies and real-world epidemic data have demonstrated COVID-19 to be inescapably airborne.[]
  2. As opposed to pandering to governments who wish to pretend that the pandemic is not happening so that everyone could go back to being dutiful workers and consumers.[]
  3. There may be more to say here in a future post, contrasting the widely differing approaches to COVID-19 mitigation for the “haves” and for the rest of us.[]