Comment by dalore | Hacker News Reader

Comment by dalore | Hacker News Reader

It's not new, it's more evidence:

At the end of May, however, an immunological study by the University of Zurich was published, which for the first time showed that the usual antibody tests that measure antibodies in the blood (IgG and IgM) can detect at most about one fifth of all coronavirus infections.

https://www.biorxiv.org/content/10.1101/2020.05.21.108308v1

At the same time, the Swiss study may explain why children usually develop no symptoms (due to frequent contact with previous corona cold viruses), and why even hotspots such as New York City found an antibody prevalence (IgG/IgM) of at most 20% – as this already corresponds to herd immunity.

The Swiss study has in the meantime been confirmed by several more studies:

A Swedish study showed that people with mild or asymptomatic disease often neutralized the virus with T-cells without the need to produce antibodies. Overall, T-cell immunity was about twice as common as antibody immunity.

https://news.ki.se/immunity-to-covid-19-is-probably-higher-t...

A large Spanish antibody study published in Lancet showed that less than 20% of symptomatic people and about 2% of asymptomatic people had IgG antibodies.

https://www.thelancet.com/journals/lancet/article/PIIS0140-6...

A German study (preprint) showed that 81% of the people who had not yet had contact with the new corona virus already had cross-reactive T-cells and thus a certain background immunity (due to contact with previous corona cold viruses).

https://www.researchsquare.com/article/rs-35331/v1

A Chinese study in the journal Nature showed that in 40% of asymptomatic persons and in 12.9% of symptomatic persons no IgG antibodies are detectable after the recovery phase.

https://www.nature.com/articles/s41591-020-0965-6

Another Chinese study with almost 25,000 clinic employees in Wuhan showed that at most one fifth of the presumably infected employees had IgG antibodies (press article).

https://www.medrxiv.org/content/10.1101/2020.06.13.20130252v...

A small French study (preprint) showed that six of eight infected family members of Covid patients developed a temporary T-cell immunity without antibodies.

https://www.medrxiv.org/content/10.1101/2020.06.21.20132449v...

1. Dozens of localities have controlled the virus via lockdowns, social distancing and masking, they all show similar curves to NY but with lower peaks. NY therefore offers no evidence that herd immunity has been reached.

2. Your Spanish study shows 90% of those with a positive PCR test also had antibodies. The low symptomatic positive rate could be easily explained by other seasonal illnesses with identical symptoms.

3. There is no evidence beyond supposition that I can see for the Wuhan clinical workers having the virus. An alternative explanation is that protective equipment and protocols were effective.

4. The idea of 80% of the population being T-cell immune seems inconsistent with the outcomes on the Diamond Princess.

I think you are cherry-picking data to support a far-fetched theory. The outcomes in confined places where the virus infects everyone, like the Diamond Princess or nursing homes, seem especially hard to square with the idea of widespread t-cell immunity.

Edit: I was misremembering the Diamond Princess, not everyone on the cruise ship got the virus. However, Marion Correctional Institute in Ohio had 80% test positive for covid; the Life Care Center in Kirkland, Washington had 2/3 test positive. These don't seem consistent with widespread T-cell immunity.

Interesting you mention the Diamond Princess, it actually supports the "far-fetched" theory. And it's not as far fetched as you think, it's gaining more ground and does explain places like New York, London, Sweden, India etc.

https://www.spectator.co.uk/article/immunity-to-coronavirus-...

"In the accidental experiment of the Diamond Princess – a close community where the infection was allowed to spread unchecked for a fortnight in January, and everyone was eventually tested – only 17 per cent of passengers and crew became infected."

New York (and similar UK and Sweden) has a higher death rate since they moved sick patients into care homes and decimated them. As you said everywhere saw similar curves no matter how strict or lax a lock down they had. Implying something else is going on and not the lock down.

Studies looking at the impacts of lock down on the curve are showing very little correlational https://www.thelancet.com/journals/eclinm/article/PIIS2589-5...

“full lockdowns and wide-spread COVID19 testing were not associated with reductions in the number of critical cases or overall mortality.”

So, to me at least, it does seem far more plausible that t-cells are more a mitigating factor then lock downs.

If I am cherry picking, seems to be lots of cherry trees to pick from.

I see no reason why t-cell should not offer some protection, like it does with other coronaviruses. And why we would assume that everyone is just as susceptible when we know the risk profile varies wildly.

EDIT: for your explaining your edit of "Life Care Center in Kirkland", the reason they have more antibodies is that we all know the older you get the less t-cell protection you have. A "life care" center one assumes is full of old people, hence lower t-cell protection. And it explains why children have more protection as their t-cell protection is stronger.

Everywhere saw a similar shape of curve, i.e. exponential increase until the lockdown, then slow exponential decrease. The peak of the curve differed widely, and countries that were slow to lock down like the UK, Sweden and USA have seen some of the worst outcomes.

Correlating lockdown policy to outcome does not make sense because lockdowns are instituted in response to case levels in the first place. It is like correlating fire trucks and fires, and finding that fire trucks cause fires because there are more of them in dry, fire-prone areas.

Sweden provides something close to a natural experiment, it has similar culture and climate to its neighbors but a far worse outcome after it did not lock down.

Prisons are not especially weighted toward older people and they have seen outbreaks with as many as 80% being infected.

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