The concept of Geometric or exponential progression

Discussions on the COVID-19 pandemic invariably include or turn into the notions of geometric or exponential progression or growth. These are mathematical concepts which many of us would have already studied in high school, but have forgotten over the years, retaining only that knowledge we use frequently today. Except for some engineers, those who are into financial investments, and epidemiologists, most of us wouldn’t care what the geometric or exponential mean.

As I said last week, the pandemic is all about science and math. The coronavirus, SARS-COV-2 is the subject of medical science, of course, but its contagiousness and ability to grow widespread follows the formulas of geometric and exponential growth. These two terms are pretty much the same, by the way, only OECD has tried to differentiate them into discrete for geometric and continuous for exponential.

Medicine uses the variable R for the rate of transmission. Simply, it’s the ability of an affected person to infect another one in the community. So, if R is 1 and there are 100 infected persons, they would infect another 100 by the time the disease cycle was completed and the original 100 got healed. If R is more than one, then it can affect more people and grow with an increasing trend, the rate of increase of which will be more as R is bigger. Left unchecked, it will affect everybody.

But R is not constant and is affected by how people behave. The health protocols --wearing masks, washing hands, and social distancing-- were designed as the most effective way of lowering R to values below 1, the lower the better. That’s how the pandemic was somewhat contained in the last half of last year. Lockdowns do have some effect but not much, because while people are restricted and isolated in smaller units --country, city, barangays, etcetera-- they still react socially within these units. What really helped was when people follow the three medical protocols. Not lockdowns.

Geometric/exponential progression causes the rapid rise of cases, and the deaths which surely follows. The lockdowns last year and the health protocols limited it in a way causing R to go below 1 and thus caused the declining curve. When those CQs were relaxed, the compliance of the health protocols went down as well, which now resulted in the recurrence of the surge, to levels the same as, if not exceeding the ones last year. After all the suffering we went through, after all the billions of pesos spent which may be now considered gone to waste, we’re going back to the same levels we were before!

Pandemics, like in math, follow the same curve. We bring R below 1, cases and death decline, we allow it to go beyond 1, they will increase. Lockdowns have little effect. What works is simple – wear masks, wash hands, follow social distancing. Again, it depends on the people and the government. But we all know it ultimately depends on the government, especially the LGUs. If they won’t do their jobs, then we will continue the roller-coaster of these geometric and exponential progressions. And the key is to convince, not coerce. Threats won’t work – information dissemination and constant reminders do.