The Delta Variant and its R0

I read the news nowadays with a growing feeling of dread insofar as the COVID-19 pandemic is concerned. As I had explained in some previous articles before, infection transmission follows both scientific (medical) and mathematical principles and while I know virtually nothing about medicine, I’m familiar with geometric and exponential functions, which, COVID-19 seems to follow to the letter. They even shifted the variant names to Greek letters, common in math!

What bothers me is that the people in general don't seem to realize the danger we are all in because of this variant. Yes, it’s more infectious, most admit; yes, it causes more severe sickness and hospitalization. It’s worse than the original and all other previous variants. But how much worse, is something we fail to realize.

Without going into the physiological differences between variants, let us simply look at the reproduction rate, R0 (pronounced R-naught or R-sub-zero). This number tells us how easily the virus spreads. It is the average number of people to whom an infected person will pass the virus, under normal situations, without any intervention or protocol. If R=1, then one sick person can infect another person in 1 infection cycle. If R < 1, we don’t have anything to worry about, the disease will die down. If it’s above 1, then cases will continue to rise, and we have to intervene to keep it in check and stop the contagion.

The original COVID-19 had an estimated R0 of 2-3. The Delta variant is estimated to have an R0 of 5-8. Measles has an R0 of 18. Say we conservatively assume the R0 of the original COVID and its Delta variant at 2.5 and 6.0, respectively. After one infection cycle, one person will infect 2.5 persons, while a person with the Delta variant will infect 6 persons. With no intervention, this will increase in the next cycle to 16 and 36 persons, respectively. On the third cycle, this will grow to 15 and 216, and so on and so forth, 39 as against 1,296 after that. That’s the reality of geometric or exponential growth.

That’s if nothing is done. But we had precautions. We had lockdowns and quarantines. We have protocols --masks, washing, social distancing. And so, we manage to control the original virus. But this new one, the Delta one, is much more vicious, and transmits much faster. We can’t even use the previous protocols in the same manner because, as you can see, the multiplier effect is much faster and progressive in nature, it literally explodes only after a few transmissions. This even with vaccinations around, which has not even taken off to the degree that it can start hindering transmission through herd immunity. We’re not even a small fraction of that level.

Calling Delta a variant gives us a false sense of security as it sounds as if this is the same virus, only a little different. No, it’s not, it’s faster and many times more vicious. We have to revise all our protocols. We need to take extraordinary precautions. Before the situation gets any worse.