I read some interesting flu discussion and wanted to share.
R0 is the basic reproduction number of an infection. It represents the amount of people an infected person is expected to infect in turn. Ie. the higher the number, the more infectious, and on an exponential scale.
Flu strains average R0 of about 1.5. Covid-19 is more like 3. Duh, we all know covid is more infectious, but this is a great thing to keep in mind when trying to understand how mitigation affects both viruses differently.
Let’s say, for argument, that lockdowns, distancing, masks, and all that stuff cut an infections R0 by half. (I doubt the true efficacy is that high - this is just an example.)
Flu drops down to 0.75. That means that, for every person that gets the flu, they’re expected to infect… less than 1 person. You can see that, as soon as R0 drops below 1, that infection is essentially “dying out.” In the meantime, covid is sitting pretty at 1.5, still infecting more and more people.
One infection shrinks and the other grows.
Another interesting facet of the flu is that it relies on summer travel for mutations to spread in the southern hemisphere in our offseason. Lockdowns halted most travel, so all last year the other side of the world didn’t experience the usual flu buildup that always swings back to us.
Some other discussion points:
For those who believe flu deaths are being switched to covid, there are places like Australia and New Zealand that don’t have a lot of covid deaths. Guess what, flu still disappeared in those places as well. Where did the flu go?
Despite the flu being decimated this season, I don’t believe there’s a chance the infection “goes extinct.” Even if its R0 is effectively less than 1 in humans this year, it has a larger R0 in various animal populations that “keep the infection alive.” Flu will be back.
And what you continue to ignore is that by doing this - while the majority of people under 70 handle the virus with only decent/minimal symptoms - letting the virus tear through the population undeterred raises the risk that it will be transmitted to people with higher risk factors (not just those over 70).
In short, allowing this to happens would mean a lot more deaths.
I know you think it’s fake (it’s not), but India is not in a good place with COVID at all. So many are getting it and it’s moving easily to those with higher risk factors.
Better to achieve hers immunity through vaccine than natural infection.
I thought I was clear that was an example to demonstrate the math. Even the R0s listed on that wikipedia page are greater ranges, and I just took their median. Feel free to do more research if you’re interested.
India’s testing out that theory as we speak.
There are dangers of allowing unabated spread. Overwhelming healthcare, increase in mutations, etc. But this thread isn’t about how to mitigate covid. My intention was to discuss the lack of flu cases around the planet.
No, I think the actual number is lower, and I said as much in the original post. I just used a round number for math.
My point was, no matter what flu’s R0 is this year, whether on the low end (1.2) or higher (1.9), it’s a lot lower than covid, and it’s entirely possible that mitigation lowers it below 1, which would see a sudden absence of flu cases.
Another obvious thing, of course, is how aerosolized covid is, which would vastly decrease the effectiveness of mitigation measures that happen to be a lot more effective on the flu. I should have included that in my original post.