[__blockcipher__]

Herd immunity is a natural emergent phenomenom. I don’t know how your “side” has suddenly decided it’s a myth. It’s just math.

BTW, you never answered my question about how Sweden’s mortality is back at or below baseline in the absence of lockdowns nor universal masking. All you did was screech angrily about politics, not realizing that it is the lockdown-loving camp that made this whole thing about about politics over public health policy.

[maxerickson]

The bullshit is that Sweden has reached herd immunity. People in this thread clearly understand that there is a certain level of population immunity where R₀ goes below 1, they are arguing that Sweden has not reached the point where things are 'normal' and R₀=1, they are taking various measures to control the virus, and the rate of spread will go up if they relax those measures. That's not unqualified 'herd immunity', it's not even close.

(https://www.businessinsider.com/sweden-decline-coronavirus-d... discusses some of the things that Sweden is doing, which are indeed largely voluntary)

[__blockcipher__]

I'll chalk it up to an innocent typo, but you got the terminology wrong. R_0 means R(t) where t=0. In other words, it by definition means the basic reproduction number which does NOT account for any level of immunity.

R, or as I prefer to call it, R(t), is the number that factors in how many have immunity. So you mean herd immunity is when R(t) < 1.

---

Anyway, I was having trouble understanding exactly what you were saying about Sweden, but to be clear, Sweden has hit herd immunity, unless you think that the utter absence of COVID mortality at this point is due to seasonality.

What you need to understand is that simplistic models view the population as homogenous, both in terms of mixing (social connections) AND susceptibility/transmissibility. Neither are true. Essentially, the people who tend to get infected sooner in the pandemic are the ones who tend to spread more, so the first, say, 10% of antibody prevalence is worth a lot more than the next 10%.

There's also the presence of pre-existing T-cell cross-reactivity; exposure to other hCoVs is protective against SARS-2. It seems that it does not protect infection, but it does make the disease course a non-issue: this probably explains the high degree of asymptomatic infection (with part of it just being explained as an artifact of the PCR cycle threshold fuckery). Technically these findings are already implicitly factored into the estimates we have for R_0, etc. (BTW, initial studies were claiming R_0 of 5.2, 5.5, etc, but now with more data it seems it's around 2, give or take)

Many, and I am in this category, believe that the true herd immunity threshold is somewhere around 20% of the population. That explains what we've seen in places like New York, Sweden, etc. This is lower than what the classic herd immunity formula would predict, because that formula does not account for a non-homogenously-mixed population (as I mentioned earlier), nor does it account for certain individuals having an innate genetic resistance that makes it less likely that they get infected.

[maxerickson]

Is Norway even more immune than Sweden then?

[evgen]

Ssshhhhhh.... Sweden can only be used as an example when you compare it to complete fuck-ups like the US or UK, or if you add in countries that were hit early before we knew how virulent covid-19 was and that it could be spread asymptomatically. If you put it into context with its similar neighbors then the failure of the herd immunity plan is laid bare.

[evgen]

So bad form to reply to one's own comment, but am I the only one who finds it quite ironic that today the Swedish PM was warning of a growing second wave there because people were not following social distancing suggestions and it turns out that they were not even close to achieving herd immunity.

[__blockcipher__]

Show me what Tegnell said. I haven't seen what the PM said but they almost certainly don't know what they're talking about.

BTW, this is what Sweden looks like now:

https://twitter.com/SeanCollins66/status/1309179008018513926