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Nationwide population-based study in Spain shows only 5% seroprevalence. thelancet.com/journals/lance… @TheLancet

I don’t think this represents the true proportion of population that is 𝙣𝙤𝙩 susceptible. Spain could not have controlled COVID if true herd immunity now is only 5%.
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Another interesting aspect of the study is the extent to which the seroprevalence varies based on the population characteristic:

90% in history of PCR positive COVID persons

~20% in persons with history of symptoms suggestive of COVID.
thelancet.com/journals/lance…
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I think a much higher proportion of the population in Spain is likely immune due to prior cross reactive immunity (humoral or cell mediated). This coupled with lower exposure dose (masks, social distancing) may be helping them not get COVID, at least not enough to seroconvert.
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Masks, social distancing, and border control measures are still important and needed because until proven otherwise we have to consider 95% of Spain is still susceptible. Cross reactive immunity is also probably not robust enough to overcome a high dose exposure.
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Besides cross reactive immunity, the 2 other probabilities that explain the cratering of new cases in Spain despite only 5% seroprevalence are 1) some predisposition-susceptibility is based on genetic factors; and 2) this is all due to test/trace/lockdown/quarantine/masks.
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Here is a thread I did earlier on susceptibility. Would be curious to see what @Rfonsi1 thinks of this data. Also @mvmateos — what do you think is going on?
Watching Switzerland too. Their relaxation timeline and cases. Their seroprevalence can’t be higher than Spain. @Rfonsi1
Italy was one of the worst affected in Europe. Their lockdown restrictions have been relaxing since early May (see timeline). Things are interesting to watch there too. One more month and I can be more confident. google.com/amp/s/www.afar…
The two countries that are puzzling are Israel and Iran. Not sure whether there is a geographic effect playing out. Or whether the first peak was ameliorated by control measures (lesser than NY or Spain). @Rfonsi1
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More from @VincentRK see all

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Vincent Rajkumar
@VincentRK
Many new studies suggest that one of the fundamental assumptions about COVID that 𝙚𝙫𝙚𝙧𝙮𝙤𝙣𝙚 is susceptible, may be wrong.

CAUTION: However, this doesn’t mean that we relax any precautions, coz the % of population susceptible is very high, & COVID is deadly.

Thread
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Study in @CellPressNews found 70-100% of people recovering from COVID have good T cell immune responses targeting the spike protein & other viral proteins. But they also found 40–60% of people who never had COVID also had T cells reactive to SARS-CoV2. cell.com/cell/fulltext/…
2/
For the group they considered unexposed to COVID they used cells collected in 2015-2018. So no chance of exposure to COVID.

These findings suggest that immune responses we generate to common corona viruses (~20% of common cold) may be cross reactive & protect against COVID.
3/
Read 11 tweets
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Vincent Rajkumar
@VincentRK
COVID vaccine approved for military use in China. My guess is that China will have hundreds of millions of doses by August.

China has crushed COVID. They don’t have enough cases to do a Phase III RCT. For their citizens this is the right call. google.com/amp/s/mobile.r….

Thread 1/
Their epidemiology leaders unlike ours have consistently got it right. They did masive testing. Elaborate contact tracing. They controlled COVID. We didn’t. Honesty they don’t need our advice. We have no credibility to advise them

Below is what our CDC acknowledged yesterday
2/
China has almost no COVID. So they either have to risk unknown efficacy & possible side effects of a vaccine that induces strong immune responses, or be at the mercy of other countries to complete their trials & sell them vaccines for a fortune. They correctly chose the former
3/
Read 6 tweets
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Vincent Rajkumar
@VincentRK
Thread on how COVID plays out in hotspots.

Look at Italy, UK, Belgium, USA. The USA looks very different.

However, when we examine the US as composed of many different “countries”, a different pattern emerges.

@ASlavitt @choo_ek @Rfonsi1
91-divoc.com/pages/covid-vi…

Thread 1/
Now look at the US as if it is composed of a few individual countries.

Northeast which was worst hit in March/April starts to look like Italy, Belgium, UK.

The West and South are behaving like countries where COVID is just now taking off; they are yet to peak.

2/
When we look at individual big Northeast States as individual “countries” they start to resemble European hotspots, Italy, Belgium, UK.

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