[wang_li]

Pfizer is already mass producing their vaccine and are saying they’ll have 100 million doses available this year and are targeting 1.3 billion next year.

The US has five million people who tested positive and have recovered. Likely also another 30-50 million who were never tested because their symptoms were to minor. And another 66-165 million who have cross reactive T-cells.

Some researchers have concluded that the herd immunity threshold for sars-cov-2 could be as low as 10% or as high as 50%. I don’t think anyone sees it as high as 80%.

https://www.bmj.com/content/370/bmj.m3563

[celticninja]

https://www.mayoclinic.org/diseases-conditions/coronavirus/i...

The mayo clinic suggests it could be 70%, and I have seen others suggest 80%. I have not seen anyone suggest as low as 10/20% so I think that suggestion is a huge outlier and even the paper you link says as much.

[bart_spoon]

There actually has been several papers posted to r/COVID19 that have suggested that the herd immunity threshold is likely overestimated. This is because vulnerability to infection isn't uniform across the population. Some people will be more likely to be infected, either due to biological reasons, like a weaker immune system, or sociological ones, like living or working in an area where transmission is far more likely. Most of the higher estimates of a herd immunity threshold of 70-80% are based on transmission dynamics from early in the pandemic, which mostly consisted of these people with higher probabilities of infection. Once this population starts to get burned out, the transmission of the virus also slows, which means that the herd immunity barrier also drops.

One of the papers hypothesized that this demonstrates why areas like NYC got hit so hard initially and have remained stable since. Seroprevalence surveys back in the early summer indicated that between 20-30% of NYC residents had contracted Covid already. The lockdowns obviously blunted the surge, but unlike other areas of the country, as NYC has opened back up, there hasn't been much of a second wave at all. With more than 2/3rds of the population still without any kind of exposure to the virus, you would expect a dense city like NYC to see a large increase. The paper concluded that this is evidence that might suggest that the herd immunity barrier is far lower than initially estimated. I've seen some papers suggest something closer to 20-50%, but nothing so low as 10%. I'll see if I can dig up some of the preprints to post here.

[lbeltrame]

That's because 70/80% estimates assume that the population is entirely vulnerable, while instead it looks like it's partially vulnerable. Hence the estimates would need adjustment.

[Izkata]

80% or so is accurate if there was no cross-reactivity and if asymptomatic is included in the case count. It's what was being reported in March or so when we didn't yet have evidence of cross-reactivity.

[jandrewrogers]

In most models, we currently assume herd immunity is 50%. We know it isn’t higher than that but we also have circumstantial evidence that it likely isn’t below 40%. A complicating factor is that we know the number of infections is much higher than the number of cases but we don’t know by how much and this is not something we can effectively measure retroactively, which makes it challenging to model precisely.