The Fifth Wave of Covid is coming, here’s why.

Photo by Fusion Medical Animation on Unsplash

Will there be a 5th wave of infections in August?

Let’s do the math and see, it’s a word problem, so bear with me. The good news is I will do all the math, you can just follow along at home.

There are 330 million Americans.

At the moment about 150 million are fully vaccinated, 30 million are partially vaccinated. 60 million were previously infected, 12 million of those were seriously ill, and probably now have strong immunity. That gives us 162 million with strong protection, plus 50 million more with some degree of protection or 212 million or 65% of the population with some degree of protection.

R0 is the number of people that an infected person would be expected to infect, in the absence of any previous immunity or steps taken to avoid infection.

Now imagine there are 100 infected people. With an R0 of 5 for the Delta variant, that means on average those 100 infected people would be expected to infect an additional 5 people each, which will lead to 500 more infections. But, thanks to vaccines and surviving past infections, 2/3 of those 500 have some degree of protection. Let’s assume for the moment that the protection is perfect and 2/3 of the 500 are safe. As a result, there are 165 infections instead of 500. This is a lot better, but the disease is still spreading.

This is actually the current situation, Covid Classic and Covid Alpha with an R0 of about 3 are being stopped by a combination of vaccines and people taking steps to avoid infections, while Covid Delta which has an R0 of 5–8 or more is still spreading.

In order for the disease to slow down and eventually stop, with an R0 of 5, we need 80%+ to have at least some degree of protection. That protection can come from vaccination, previous infection, or just avoiding infection by avoiding situations where Covid spreads.

25% of the population still seems to be an anti-vaxxer, so getting above a 75% vaccination rate seems unlikely at the moment. Some of the anti-vaxxers were previously infected, assuming an anti-vaxxer is as likely to get exposed as the average person, 20% of the anti-vaxxers probably have some degree of protection from a previous infection.

So it would seem that we could get to 80% of the population having some degree of protection through vaccinations and infections, at which point with an R0 of 5, it wouldn’t take much in the way of behavior to slow down and eventually stop Covid Delta.

However, children under 12 still cannot be vaccinated, and anti-vaxxers are unlikely to take their kids aged 12–18 to get vaccinated, so getting to 80%+ with some protection will be a challenge. And that assumes that Covid Delta has an R0 of 5, which is on the low end of estimates.

Given the percentage of anti-vaxxers and that the R0 of Covid Delta is between 5 and 8, it seems likely that Covid Delta will continue to spread.

The percentage of infections that are with the Delta variant is about 10% and currently doubling every two weeks, while the overall number of cases continues to fall more slowly. The Gamma variant is a kind of wild card in all of this, as it is spreading quickly, but in fewer places. The Gamma variant is formerly known as the Brazilian Variant and is unusual among the variants as it has been documented in Brazil as having killed thousands of the very young, including babies. Some local areas are very concerned about the spread of Gamma, but for most of the country the Delta variant is the larger concern.

At the current rate of spread of Covid Delta, and the current rate of decline of Covid Classic and Covid Alpha, I believe we will see a continued decline of total infections until sometime in or around August, at which point we will see infections rising again, creating the 5th wave, this time made up of the Delta variant and possibly the Gamma variant.

That would be bad enough on its own, but the Delta variant is also believed to result in 80% more hospitalizations and presumably a higher percentage of deaths as well. In January of 2021, the USA peaked at a 7 day moving average of 256,000 daily infections which then resulted in a 7 day moving average of 3,400 daily deaths. If those infections had been with the Delta variant instead of Covid Classic and Covid Alpha (Previously known as the Kent or UK variant) we might have seen as many as 6,100 daily deaths.

The 5th wave could be avoided with a higher percentage of people getting vaccinated, or more intense behavior changes, so this would qualify as a heads up or a warning, as opposed to a prediction. I’m not saying a 5th wave is inevitable, it’s currently the most likely path, based on the current situation. If the situation changes, the outcome can change. While that seems unlikely at the moment, there is cause for some hope.

Anti-vaxxers might realize that while they are only 25% of the population, according to doctors at hospitals where they keep track of such things, the unvaccinated are currently 99% of the covid deaths so hundreds of people are needlessly dying each day. That math might sink in, possibly soon enough to matter.

Hotspot counties and states might modify their rules, which might change behavior enough to avoid the 5th wave. A lot of places have relaxed their mask-wearing policies, those could be put back in place. Bars could be closed down again.

Something else, unanticipated could happen, maybe the hot summer weather will prevent infections long enough for enough people to get vaccinated. Or maybe someone will find an amazing new treatment that is easy to administer and works very quickly.

But at the moment, if nothing changes the trajectory of the disease we will probably see a 5th wave in or around August of this year, probably closer to the beginning of August than the end.

I read a lot and try to make sense out of what I read. Do the facts as reported make sense or is there more going on?