Without a Vaccine, Researchers Say, Herd Immunity May Never Be Achieved | Hacker News Reader

Without a Vaccine, Researchers Say, Herd Immunity May Never Be Achieved

npr.org

11 pointsvonmoltke8 comments

How do you explain deaths in Sweden, UK, New York and other hotspots hitting essentially zero?

Sweden had 10 deaths yesterday, the UK had 123. While that may sound like "essentially zero" when compared to the US, it's not.

The decline in deaths is due to the decline in cases which in turn are caused by improved preventative measures such as social distancing and masks.

That's answered in the article that people are taking proactive measures because they don't want to expose themselves for the sake of herd immunity.

New York City has an estimated 13% of people have had Covid-19. That's nowhere near the 50-80% needed mentioned in this article.

Just the back-of-the-envelope time and scale needed for herd immunity shows how far away we are. The US would need 200 days of 1 million new people each day catching it to reach herd immunity. That's with the most generous assumptions about reinfection. Any health system (especially the US') would crumble under that load.

Hard to get herd immunity from something you can get multiple times and which seem to be more deadly subsequent times.

> Hard to get herd immunity from something you can get multiple times and which seem to be more deadly subsequent times.

what's the evidence of this?

I heard anecdotes of reinfection with worse symptoms on subsequent infections a few weeks ago; this looks to be the article [1]. I haven't heard widespread confirmation or studies showing this yet.

[1] https://www.vox.com/2020/7/12/21321653/getting-covid-19-twic...

There are false negatives and positives in the tests. In Macaques they could not reinfect them, so this doesn't seem that likely.

None AFAIK.

Post infection, people seem to have robust neutralizing antibody responses and T cell immunity. Even if antibody responses are not measurably durable, latent B cell memory is _highly_ likely (e.g. antibody production restarts when the antigen is detected)

Antibody dependent enhancement seems to be unlikely given that the SARS-COV-2 spike protein seems relatively stable.

So once infected you are highly likely protected in the future.

That doesn't mean you can't be reinfected and be contagious... just that rather than go into full blown ARDS/sepsis, you would have a mild cold.

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