Covid-19 Partial existing immunity in unexposed populations

  • #1
jim mcnamara
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Summary:

A hypothesis to help explain the wildly varying responses to Covid-19
Selective and cross-reactive SARS-CoV-2 T cell epitopes in unexposed humans
Science 04 Aug 2020:
eabd3871
DOI: 10.1126/science.abd3871
URL: https://science.sciencemag.org/content/early/2020/08/04/science.abd3871

[Background]
The Coronavirus family of viruses is a cause of multiple human illnesses: diarrhea & vomiting (enteric), colds, SARS, MERS, Covid-19

Example from 2009, case reports on nasal mucosa damage from Coronavirus cold infections:
https://www.tandfonline.com/doi/abs/10.3109/00016488909127507

To reduce confusion, enteric Coronavirus infections - the ones that caused violent vomiting and diarrhea on cruise vessels a few years back - have been known since the 1970's example:
https://link.springer.com/content/pdf/10.1007/BF01314383.pdf
The enteric ones are NOT what the current paper is discussing.

Bottom line:
This means the previous exposure window to one of the coronavirus cold agents in the paper under discussion is long. Whether or not partial immunity persists from way back then -- I did not find a reference that quantifies any of this.

It would be very interesting to see if immunity to Covid-19 could arise from some of the nasties cousins, and the possibility of a universal vaccine:
https://www.sciencedirect.com/science/article/pii/S0092867420308126

[/Background]


Paper discussion:
Populations of humans that have not been exposed to Covid-19 show some immune memory cells that can respond to the Covid-19 virus. This is due to previous cold causing Coronavirus infections. The authors estimate 20% - 50% of the human population has this partial immunity.


Coronavirus colds have been known since at least the early 1980's - from 1986:
https://academic.oup.com/jid/article/154/3/443/819151

It does not appear to mention the enteric Coronavirus group, which should be of interest.

This would explain, in part, why so many people in modern populations exposed to the virus do not show severe symptoms - so-called asymptomatic infections. Because. The colds someone had a few years ago imparted partial immunity to the new virus. Not all colds are caused by this group of pathogens. Rhinovirus (another group of virus) also cause colds, for example.

Also remember that the cruise ship epidemics are caused by another enteric group of the virus family. It may be of value to explore this as another source of "stealth" Covid-19 immunity.
 
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Answers and Replies

  • #2
Drakkith
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Interesting. Reminds me smallpox and cow pox. I'd gladly take the 'cow pox' coronavirus infection to avoid Covid-19.
 

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