3 ms·

Is anyone even seriously claiming that a disease that spreads twice as fast is going to infect twice as many people? As long as the effective R0 of a disease r

Is anyone even seriously claiming that a disease that spreads twice as fast is going to infect twice as many people? As long as the effective R0 of a disease remains greater than 1, it's eventually going to infect the same amount of people — everyone (over the long term). Greater R0 rate just means it spreads faster. The real concerns about omicron are that: 1) A rapid initial spread will overwhelm the healthcare system and 2) that if its basic R0 rate is sufficiently high, then even after remedial measures are taken, we will still be left with an effective R0 rate above 1 for quite some time.

sudosysgen 5y ago
That's not how it works. Diseases dont infect everyone. Assuming no reinfection, at R0 of 1.3 a disease will only infect around 30% of the population.
- zuminator 5y ago
  If I conveyed the impression that I thought the effective R0 could remain above 1 indefinitely, that is my error. But why assume no reinfection, that's not what we're seeing so far with SARS-CoV-2.
  - sudosysgen 5y ago
    That is not quite what R0 means. R0 is the reproductive rate in a naive population. I believe the variable you are looking for is R(t), which is the effective reproductive rate at any point of time.
    - zuminator 5y ago
      Thank you. I've seen the phrase "effective R0" used, for example, here [0], but I can see that you are correct that R(t) is the generally accepted epidemiological term. [0] https://labblog.uofmhealth.org/rounds/how-scientists-quantify-intensity-of-an-outbreak-like-covid-19 https://labblog.uofmhealth.org/rounds/how-scientists-quantif...
      - clairity 5y ago
        this is a mathematical convention, not simply an epidemiological term. the 0th term of any function, like R0, is generally understood as the initial condition constant (at time t=0). R(t) is a function of time and R0 is the value of R at time 0, the initial condition. R0 tells you exactly nothing about the future, it only pins down the starting point (which is important information, but not the be-all-and-end-all of it). i’ve been mildly amused/dismayed by the constant misplaced focus on R0 over the past 2 years by the media/laypeople, given this essential context.
        oneoff786 5y ago
        That’s not correct. While R0 is indeed R at time 0, time is not the important part of that. It’s that at time 0 everyone is presumed susceptible so the growth is going to be as exponential as it’s going to get. R0 is a strong indicator of the limits of how the disease will spread and is very useful for predicting the future, both in terms of the speed of the initial exponential spread, but also the upper bound on spread that the disease is likely to encounter.
        clairity 5y ago
        no, the epidemiological model in question has two degrees of freedom, and one of those degrees is stipulated by the assumed shape of the curve (exponential, even though that's a poor fit overall, logistic being a better fit). R0 does not constrain the other degree of freedom; it only gives you the initial condition. it requires knowing that other degree of freedom, which you're making implicit assumptions about, that governs what you can say about the rapidness of spread and makes some statements about bounding. this is rudimentary calculus and linear modeling.
oneoff786 5y ago
Nope. You’re still making the same mistake. That is not how R0 works. You are falsely assuming that the exponential growth period of the virus stays the same forever. The virus does not reach 100%. R0 as a general trait of a disease assumes everyone is susceptible. That is not how diseases work. There are many diseases with R0 > 1 and guess what? Not everyone got them. I know you’re caveating “effective R0” but frankly that’s stupid. Saying as long it keeps growing it will keep growing purposefully ignores the point I am making which is that it won’t keep growing. The effective R0 falls on its own. That is the point being made. It will absolutely not reach 100% of the population. Not even close.
- zuminator 5y ago
  > the point I am making which is that it won’t keep growing. And what I'm saying to you is that nobody believes otherwise. It's all known that diseases are self-limiting, and infection rates follow an s-curve and eventually drop off. This isn't a groundbreaking revelation.
  - oneoff786 5y ago
    In my experience the majority of people assume that exponential growth means a small increase in spread rate means and exponentially larger number of people will be infected, and that “everyone” will get omicron. I’m not claiming to have a novel epidemiological insight. I’m claiming that most people get this wrong and are panicking about omicron because they don’t get this.

sudosysgen 5y ago

That's not how it works. Diseases dont infect everyone. Assuming no reinfection, at R0 of 1.3 a disease will only infect around 30% of the population.

zuminator 5y ago
If I conveyed the impression that I thought the effective R0 could remain above 1 indefinitely, that is my error. But why assume no reinfection, that's not what we're seeing so far with SARS-CoV-2.
- sudosysgen 5y ago
  That is not quite what R0 means. R0 is the reproductive rate in a naive population. I believe the variable you are looking for is R(t), which is the effective reproductive rate at any point of time.
  - zuminator 5y ago
    Thank you. I've seen the phrase "effective R0" used, for example, here [0], but I can see that you are correct that R(t) is the generally accepted epidemiological term. [0] https://labblog.uofmhealth.org/rounds/how-scientists-quantify-intensity-of-an-outbreak-like-covid-19 https://labblog.uofmhealth.org/rounds/how-scientists-quantif...
    - clairity 5y ago
      this is a mathematical convention, not simply an epidemiological term. the 0th term of any function, like R0, is generally understood as the initial condition constant (at time t=0). R(t) is a function of time and R0 is the value of R at time 0, the initial condition. R0 tells you exactly nothing about the future, it only pins down the starting point (which is important information, but not the be-all-and-end-all of it). i’ve been mildly amused/dismayed by the constant misplaced focus on R0 over the past 2 years by the media/laypeople, given this essential context.
      - oneoff786 5y ago
        That’s not correct. While R0 is indeed R at time 0, time is not the important part of that. It’s that at time 0 everyone is presumed susceptible so the growth is going to be as exponential as it’s going to get. R0 is a strong indicator of the limits of how the disease will spread and is very useful for predicting the future, both in terms of the speed of the initial exponential spread, but also the upper bound on spread that the disease is likely to encounter.
        clairity 5y ago
        no, the epidemiological model in question has two degrees of freedom, and one of those degrees is stipulated by the assumed shape of the curve (exponential, even though that's a poor fit overall, logistic being a better fit). R0 does not constrain the other degree of freedom; it only gives you the initial condition. it requires knowing that other degree of freedom, which you're making implicit assumptions about, that governs what you can say about the rapidness of spread and makes some statements about bounding. this is rudimentary calculus and linear modeling.

oneoff786 5y ago

Nope. You’re still making the same mistake. That is not how R0 works. You are falsely assuming that the exponential growth period of the virus stays the same forever. The virus does not reach 100%. R0 as a general trait of a disease assumes everyone is susceptible. That is not how diseases work. There are many diseases with R0 > 1 and guess what? Not everyone got them. I know you’re caveating “effective R0” but frankly that’s stupid. Saying as long it keeps growing it will keep growing purposefully ignores the point I am making which is that it won’t keep growing. The effective R0 falls on its own. That is the point being made. It will absolutely not reach 100% of the population. Not even close.

zuminator 5y ago
> the point I am making which is that it won’t keep growing. And what I'm saying to you is that nobody believes otherwise. It's all known that diseases are self-limiting, and infection rates follow an s-curve and eventually drop off. This isn't a groundbreaking revelation.
- oneoff786 5y ago
  In my experience the majority of people assume that exponential growth means a small increase in spread rate means and exponentially larger number of people will be infected, and that “everyone” will get omicron. I’m not claiming to have a novel epidemiological insight. I’m claiming that most people get this wrong and are panicking about omicron because they don’t get this.