4 ms·

Yes good point, this is early work but definitely a necessary step toward answering an important question. It's important to note the tremendous amount of evid

Yes good point, this is early work but definitely a necessary step toward answering an important question. It's important to note the tremendous amount of evidence from a wide body of peer-reviewed literature which supports the fact that immunity acquired through natural infection provides protection against reinfection that is at least equally effective as vaccination. This fact has been repeatedly demonstrated in multiple large scale and long term serological studies [1][2][3][4][5]. - A previous history of SARS-CoV-2 infection was associated with an 84% lower risk of infection, with median protective effect observed 7 months following primary infection. This time period is the minimum probable effect because seroconversions were not included. This study shows that previous infection with SARS-CoV-2 induces effective immunity to future infections in most individuals. [1] (N=25,661) - The study results suggest that reinfections are rare events and patients who have recovered from COVID-19 have a lower risk of reinfection. Natural immunity to SARS-CoV-2 appears to confer a protective effect for at least a year, which is similar to the protection reported in recent vaccine studies. [3] (N=15,075) - Reinfection is rare in the young and international population of Qatar. Natural infection appears to elicit strong protection against reinfection with an efficacy ~95% for at least seven months. [4] (N=192,967) - The degree of protection (10-fold) associated with seropositivity appears to be comparable to that observed in the initial reports of the efficacy of mRNA vaccines in large clinical trials. [5] (N=3,257,478) The OP is one of the first and largest scale studies to evaluate the risk of reinfection - in the context of the delta variant which is currently dominant in many countries around the world - by directly comparing naturally acquired immunity to vaccine-induced immunity. > those vaccinated are still at a 5.96-fold increased risk for breakthrough infection and at a 7.13-fold increased risk for symptomatic disease compared to those previously infected. > SARS-CoV-2-naïve vaccinees were also at a greater risk for COVID-19-related-hospitalization compared to those who were previously infected. If the OP study holds up to peer-review (which it likely will), then we can expect further studies attempting to replicate this finding, and even more studies attempting to explain why naturally acquired immunity induces a more robust immune response. The findings from those studies will be leveraged in the design of future vaccines - so these results will be a win just about any way you look at them. [1] SARS-CoV-2 infection rates of antibody-positive compared with antibody-negative health-care workers in England: a large, multicentre, prospective cohort study (SIREN) https://pubmed.ncbi.nlm.nih.gov/33844963/ https://pubmed.ncbi.nlm.nih.gov/33844963/ [2] Risk of Reinfection After Seroconversion to Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2): A Population-based Propensity-score Matched Cohort Study https://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciab495/6287116 https://academic.oup.com/cid/advance-article/doi/10.1093/cid... [3] Assessment of SARS-CoV-2 Reinfection 1 Year After Primary Infection in a Population in Lombardy, Italy https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2780557 https://jamanetwork.com/journals/jamainternalmedicine/fullar... [4] SARS-CoV-2 antibody-positivity protects against reinfection for at least seven months with 95% efficacy https://www.sciencedirect.com/science/article/pii/S2589537021001413 https://www.sciencedirect.com/science/article/pii/S258953702... [5] Association of SARS-CoV-2 Seropositive Antibody Test With Risk of Future Infection https://jamanetwork.com/journals/jamainternalmedicine/fullarticle/2776810 https://jamanetwork.com/journals/jamainternalmedicine/fullar...

tynpeddler 5y ago
I saw some replies to the OP where people were implying that the study results have been known for some time and there's some kind of fanatical, pro-vaxx conspiracy which was suppressing this information. This is what motivated my original post. Other than that, I agree with pretty much everything you just said. One thing to keep in mind when it comes to policy however, is data quality. The vaccine trials were double blind, controlled studies, which are the highest quality of medical study. This is why the short term, vaccine efficacy results were quickly acted on. By necessity, the OP and the studies you linked are retrospective, observational studies which are considerably more difficult to analyze correctly, and usually provide lower confidence results. Which is why the Israel study is so important (they seem to have high data quality) and why we're waiting for so many of these studies to come in before changing public health recommendation. One concern I do have about the Israeli data is that the paper on waning vaccine efficacy is using de-anonymized data, which means that for privacy and national security reasons, it's more difficult for the scientific community to double check their results.
- criticaltinker 5y ago
  Yeah good points all around. Just wanted to mention that even in the high quality phase 3 vaccine trials they found evidence that immunity acquired from previous infection was effective at preventing subsequent symptomatic illness. Obviously that wasn't the primary goal so it was hardly even mentioned in the published papers, but you can see it in the raw data. For example, from the Moderna phase 3 RCT [1] see table S17 on page 42 [2]. Out of the people with natural immunity from previous infection: only 1 out of 337 unvaccinated people were reinfected, and 0 out of 343 vaccinated people were reinfected. Admittedly they didn't have a large number of participants in this cohort, so their statistical power was limited in this respect, perhaps contributing to their rational for not mentioning it as a primary finding. [1] Efficacy and Safety of the mRNA-1273 SARS-CoV-2 Vaccine (Moderna) https://www.nejm.org/doi/full/10.1056/nejmoa2035389 https://www.nejm.org/doi/full/10.1056/nejmoa2035389 [2] Table S17. Vaccine Efficacy by SARS-COV-2 Status, Modified Intent-to-Treat https://www.nejm.org/doi/suppl/10.1056/NEJMoa2035389/suppl_file/nejmoa2035389_appendix.pdf https://www.nejm.org/doi/suppl/10.1056/NEJMoa2035389/suppl_f...

tynpeddler 5y ago

I saw some replies to the OP where people were implying that the study results have been known for some time and there's some kind of fanatical, pro-vaxx conspiracy which was suppressing this information. This is what motivated my original post. Other than that, I agree with pretty much everything you just said. One thing to keep in mind when it comes to policy however, is data quality. The vaccine trials were double blind, controlled studies, which are the highest quality of medical study. This is why the short term, vaccine efficacy results were quickly acted on. By necessity, the OP and the studies you linked are retrospective, observational studies which are considerably more difficult to analyze correctly, and usually provide lower confidence results. Which is why the Israel study is so important (they seem to have high data quality) and why we're waiting for so many of these studies to come in before changing public health recommendation. One concern I do have about the Israeli data is that the paper on waning vaccine efficacy is using de-anonymized data, which means that for privacy and national security reasons, it's more difficult for the scientific community to double check their results.

criticaltinker 5y ago
Yeah good points all around. Just wanted to mention that even in the high quality phase 3 vaccine trials they found evidence that immunity acquired from previous infection was effective at preventing subsequent symptomatic illness. Obviously that wasn't the primary goal so it was hardly even mentioned in the published papers, but you can see it in the raw data. For example, from the Moderna phase 3 RCT [1] see table S17 on page 42 [2]. Out of the people with natural immunity from previous infection: only 1 out of 337 unvaccinated people were reinfected, and 0 out of 343 vaccinated people were reinfected. Admittedly they didn't have a large number of participants in this cohort, so their statistical power was limited in this respect, perhaps contributing to their rational for not mentioning it as a primary finding. [1] Efficacy and Safety of the mRNA-1273 SARS-CoV-2 Vaccine (Moderna) https://www.nejm.org/doi/full/10.1056/nejmoa2035389 https://www.nejm.org/doi/full/10.1056/nejmoa2035389 [2] Table S17. Vaccine Efficacy by SARS-COV-2 Status, Modified Intent-to-Treat https://www.nejm.org/doi/suppl/10.1056/NEJMoa2035389/suppl_file/nejmoa2035389_appendix.pdf https://www.nejm.org/doi/suppl/10.1056/NEJMoa2035389/suppl_f...