The mathematics of variants

I’ll just try to examine the math about these COVID-19 variants. For sure, I would not be able to discuss the science about it as I have no medical background whatsoever, but we can hypothesize about it. There had been quite a number of variants since the pandemic started two years ago, quite numerous in fact, although just a few were of significance as to appear in the news. A variant is a new strain of virus which appears when there are mutations in the make-up of a virus. The virus mutates in order to escape the resistance against it and to survive. They are important because they make the pandemic worse.

Variants can be classified into two. They’re called variants of interest if they have mutations that are suspected or known to cause significant changes and are circulating widely. They become variants of concern if it is known to spread more easily, cause more severe disease, escape the body’s immune response, change clinical presentation, or decrease effectiveness of our response against them. So far, the most notable were the Alpha, Beta, Gamma, Delta, and Omicron, the last two being the most recent and the worst ones.

Variants can have a lot of effects – changes in the way they behave. But if we read the news and literature right, the two more challenging ones are transmissibility (how infectious it is), and severity (causing worse sickness resulting in more hospitalization and death). There may be other changes too – resistance to vaccines, length of sickness, etc., but usually, the medical specialists are concerned with transmissibility and severity as these define the seriousness of the variant and its effect on the overall situation of the pandemic.

The virus can mutate in any number of ways in each aspect, positively or negatively – more transmissible or less transmissible, more severe, or less severe – same as the other aspects, too, so there is a vast number of permutations possible. We can’t predict them all accurately, but we can use statistical tools in assessing the probability of each to happen. Taking the cue from the medical professionals, we can focus only on transmissibility and severity, as these are the ones that matter.

The mutations are quite random; hence, the greater possibility is that they take the form of a normal curve in their spread, crowded near the present state and tapering scarcely outward to be more or less, transmissible, or severe. And their incidence is quite nil. But they do happen which is why we have variants. However, transmissibility always governs because the more transmissible variants always ease out the previous one (Delta replaced the previous ones; Omicron replaced Delta). Severity does not govern here, transmissibility does. The next variant of concern will be more transmissible than Omicron. Whether it would be more severe is something we don’t know.

But since both aspects follow the same normal curve, the greater possibility will be that it won’t be much more severe or much less severe. Probably, it would just be the same. But hopefully less severe. Transmissibility does have its physical limits. The pandemic will then become endemic. And we will be back to normal again. Until the next pandemic…