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Sadly the only answer to the question posed in the title is "yes".
If we are to start quoting studies, might I suggest that the authors might have better used a quotation from the conclusion section of their reference number 6 [1] as follows, "Understanding the distribution, frequency and protective capacity of pre-existing structural or non-structural protein-associated SARS-CoV-2 cross-reactive T cells could be important for the explanation of some of the differences in infection rates or pathology observed during this pandemic". In other words, the only demonstration of "immunity" demonstrated by Le Bert et al is that cross-reactive T-cells exist, not that they actually provide *any degree* of functional, protective immunity. While demonstrating that cross-reactive T-cells exist is evidence of "immunity" in the strict, technical sense, in that someone can find at least one individual T-cell or B-cell clone involved in adaptive immunity which recognises at least one cross-reactive antigen epitope, to make the leap from this to concluding that this is absolute, incontrovertible evidence of population level protective immunity is somewhat difficult to justify.
Would the authors be as happy to work without PPE treating Ebola patients in Central Africa, convinced of their own absolute pre-existing protective immunity thanks to a similar study telling them that he had "some T-cells" which responded to "some epitopes" from the Ebola virus?
I would humbly suggest that we actually have evidence suggesting the exact opposite, that in fact we have *no* significant, population level, pre-existing immunity in the form of a study performed on the crew of 122 people aboard a fishing trawler which set out from Seattle in May, but had to return to port after only 18 days due to one of the crew suffering from Covid which required hospitalisation [2]. They found that, out of 120 crew-members for whom testing results were available, 85.2% of those crew-members who did not have pre-existing neutralising antibodies were infected with SARS-CoV-2 while at sea. Given the rapid spread of SARS-CoV-2 aboard ship, I would expect that the crew would have been similarly vulnerable to frequent infections from the 4 species of cold-causing coronavirus, although antibody levels to other human coronaviruses were not formally assessed.
Taking into account the additional fact that the crew of a fishing trawler are far more likely to be amongst the fittest members of society rather than the frail, elderly or significantly co-morbid, I would consider this study to be the best evidence we currently have as to the likely levels of true protective immunity prevalent amongst the general population, and this study suggests this immunity is at a very low or even non-existent level.
Dr T P Fagan
MBChB PhD BA
[1] SARS-CoV-2-specific T cell immunity in cases of COVID-19 and SARS, and uninfected controls (https://www.nature.com/articles/s41586-020-2550-z)
[2] Neutralizing Antibodies Correlate with Protection from SARS-CoV-2 in Humans during a Fishery Vessel Outbreak with a High Attack Rate
Amin Addetia, Katharine H. D. Crawford, Adam Dingens, Haiying Zhu, Pavitra Roychoudhury, Meei-Li Huang, Keith R. Jerome, Jesse D. Bloom, Alexander L. Greninger (https://jcm.asm.org/content/58/11/e02107-20)
Re: Should we continue covid-19 suppression measures based on a transmission model that ignored pre-existing human immunity?
Dear Editor,
Sadly the only answer to the question posed in the title is "yes".
If we are to start quoting studies, might I suggest that the authors might have better used a quotation from the conclusion section of their reference number 6 [1] as follows, "Understanding the distribution, frequency and protective capacity of pre-existing structural or non-structural protein-associated SARS-CoV-2 cross-reactive T cells could be important for the explanation of some of the differences in infection rates or pathology observed during this pandemic". In other words, the only demonstration of "immunity" demonstrated by Le Bert et al is that cross-reactive T-cells exist, not that they actually provide *any degree* of functional, protective immunity. While demonstrating that cross-reactive T-cells exist is evidence of "immunity" in the strict, technical sense, in that someone can find at least one individual T-cell or B-cell clone involved in adaptive immunity which recognises at least one cross-reactive antigen epitope, to make the leap from this to concluding that this is absolute, incontrovertible evidence of population level protective immunity is somewhat difficult to justify.
Would the authors be as happy to work without PPE treating Ebola patients in Central Africa, convinced of their own absolute pre-existing protective immunity thanks to a similar study telling them that he had "some T-cells" which responded to "some epitopes" from the Ebola virus?
I would humbly suggest that we actually have evidence suggesting the exact opposite, that in fact we have *no* significant, population level, pre-existing immunity in the form of a study performed on the crew of 122 people aboard a fishing trawler which set out from Seattle in May, but had to return to port after only 18 days due to one of the crew suffering from Covid which required hospitalisation [2]. They found that, out of 120 crew-members for whom testing results were available, 85.2% of those crew-members who did not have pre-existing neutralising antibodies were infected with SARS-CoV-2 while at sea. Given the rapid spread of SARS-CoV-2 aboard ship, I would expect that the crew would have been similarly vulnerable to frequent infections from the 4 species of cold-causing coronavirus, although antibody levels to other human coronaviruses were not formally assessed.
Taking into account the additional fact that the crew of a fishing trawler are far more likely to be amongst the fittest members of society rather than the frail, elderly or significantly co-morbid, I would consider this study to be the best evidence we currently have as to the likely levels of true protective immunity prevalent amongst the general population, and this study suggests this immunity is at a very low or even non-existent level.
Dr T P Fagan
MBChB PhD BA
[1] SARS-CoV-2-specific T cell immunity in cases of COVID-19 and SARS, and uninfected controls (https://www.nature.com/articles/s41586-020-2550-z)
[2] Neutralizing Antibodies Correlate with Protection from SARS-CoV-2 in Humans during a Fishery Vessel Outbreak with a High Attack Rate
Amin Addetia, Katharine H. D. Crawford, Adam Dingens, Haiying Zhu, Pavitra Roychoudhury, Meei-Li Huang, Keith R. Jerome, Jesse D. Bloom, Alexander L. Greninger (https://jcm.asm.org/content/58/11/e02107-20)
Competing interests: No competing interests