3 ms·

>a study of 52,238 patients showing zero incremental benefit from the jab to the previously infected This study ended May 15, 2021, and it notes that: >Lastly

by nokcha 5y ago

>a study of 52,238 patients showing zero incremental benefit from the jab to the previously infected This study ended May 15, 2021, and it notes that: >Lastly, it is necessary to emphasize that these findings are based on the prevailing assortment of virus variants in the community during the study. It is not known how well these results will hold if or when some of the newer variants of concern become prominent. Another study found that, for people already seropositive for SARS-CoV-2 antibodies from a previous infection, getting the first dose of an mRNA vaccine increased antibody titers by two orders of magnitude on average [1] but that the 2nd dose had no effect on antibody titers. [1] Florian Krammer, et al. "Antibody responses in seropositive persons after a single dose of SARS-CoV-2 mRNA vaccine." New England Journal of Medicine (2021). https://www.nejm.org/doi/full/10.1056/NEJMc2101667 https://www.nejm.org/doi/full/10.1056/NEJMc2101667

timr 5y ago
"for people already seropositive for SARS-CoV-2 antibodies from a previous infection, getting the first dose of an mRNA vaccine increased antibody titers by two orders of magnitude on average" That's not what this says -- you're extrapolating that the vaccine somehow changed the immune response, when this letter is only providing data that people who already had Covid had a clear, ~immediate antibody response to vaccination. That's exactly what you expect to happen when immune people see an antigen for a second time. In other words, the previously infected recipients already had a well-primed immune response. The vaccination isn't necessarily doing anything to increase the response -- it's just the expected reaction of an already-primed immune system, when it a bolus of antigens it already knows about is injected into the body: > The antibody titers of vaccinees with preexisting immunity were 10 to 45 times as high as those of vaccinees without preexisting immunity at the same time points after the first vaccine dose (e.g., 25 times as high at 13 to 16 days) and also exceeded the median antibody titers measured in participants without preexisting immunity after the second vaccine dose by more than a factor of 6. If anything, this letter (not a paper) provides further evidence that vaccination for the previously infected is not necessary.
- nokcha 5y ago
  >That's not what this says I admit I'm not medically trained, but the graph [1] seems pretty clear to me, and the authors said: > In contrast, participants with SARS-CoV-2 antibodies at baseline before the first vaccine injection rapidly developed uniform, high antibody titers within days after vaccination (median AUC before vaccination, 90 [43 participants]; >at 0 to 4 days, 133 [7 participants]; >at 5 to 8 days, 14,208 [15 participants]; >at 9 to 12 days, 20,783 [8 participants]; >at 13 to 16 days, 25,927 [20 participants]; >at 17 to 20 days, 11,755 [4 participants]; >at 21 to 27 days, 19,534 [14 participants]; and >after the second dose, 22,509 [19 participants]) [1] https://www.nejm.org/na101/home/literatum/publisher/mms/journals/content/nejm/2021/nejm_2021.384.issue-14/nejmc2101667/20210405/images/img_xlarge/nejmc2101667_f1.jpeg https://www.nejm.org/na101/home/literatum/publisher/mms/jour...
  - timr 5y ago
    The graph is quite clear. It shows that seropositive (previously infected) people had a higher pre-existing antibody level before vaccination, and it rapidly increased at days 5-8 post-vaccination -- faster and stronger than in unexposed people. It takes 28+ days and a second dose for the unexposed group to approach the titers seen in the group who already had Covid, and they still don't quite get there. Most notably, even those previously infected people with ~0 titers at baseline rapidly developed high levels of antibodies at 5-8 days after vaccination. It's a small group, but the rapid nature of the response is telling. This data is clear that the infected people had a rapid, robust immune response to vaccination. It cannot tell you what you're trying to infer -- that the vaccination itself increased the immune response. To determine that, you'd need to do some other experiment.
    - Pyramus 5y ago
      I don't follow your argumentation - why would extremely high antibody titres not almost certainly result in a better immune response? On the contrary, from all that we know today, wouldn't we expect people with high IgA titres to even develop neutralizing immunity, at least in the weeks after titres peak?
nradov 5y ago
Higher antibody levels don't necessarily mean a lower risk of disease. While that's possible it remains unproven. There's more to the immune system than just circulating antibodies.

by nokcha 5y ago

timr 5y ago

"for people already seropositive for SARS-CoV-2 antibodies from a previous infection, getting the first dose of an mRNA vaccine increased antibody titers by two orders of magnitude on average" That's not what this says -- you're extrapolating that the vaccine somehow changed the immune response, when this letter is only providing data that people who already had Covid had a clear, ~immediate antibody response to vaccination. That's exactly what you expect to happen when immune people see an antigen for a second time. In other words, the previously infected recipients already had a well-primed immune response. The vaccination isn't necessarily doing anything to increase the response -- it's just the expected reaction of an already-primed immune system, when it a bolus of antigens it already knows about is injected into the body: > The antibody titers of vaccinees with preexisting immunity were 10 to 45 times as high as those of vaccinees without preexisting immunity at the same time points after the first vaccine dose (e.g., 25 times as high at 13 to 16 days) and also exceeded the median antibody titers measured in participants without preexisting immunity after the second vaccine dose by more than a factor of 6. If anything, this letter (not a paper) provides further evidence that vaccination for the previously infected is not necessary.

nokcha 5y ago
>That's not what this says I admit I'm not medically trained, but the graph [1] seems pretty clear to me, and the authors said: > In contrast, participants with SARS-CoV-2 antibodies at baseline before the first vaccine injection rapidly developed uniform, high antibody titers within days after vaccination (median AUC before vaccination, 90 [43 participants]; >at 0 to 4 days, 133 [7 participants]; >at 5 to 8 days, 14,208 [15 participants]; >at 9 to 12 days, 20,783 [8 participants]; >at 13 to 16 days, 25,927 [20 participants]; >at 17 to 20 days, 11,755 [4 participants]; >at 21 to 27 days, 19,534 [14 participants]; and >after the second dose, 22,509 [19 participants]) [1] https://www.nejm.org/na101/home/literatum/publisher/mms/journals/content/nejm/2021/nejm_2021.384.issue-14/nejmc2101667/20210405/images/img_xlarge/nejmc2101667_f1.jpeg https://www.nejm.org/na101/home/literatum/publisher/mms/jour...
- timr 5y ago
  The graph is quite clear. It shows that seropositive (previously infected) people had a higher pre-existing antibody level before vaccination, and it rapidly increased at days 5-8 post-vaccination -- faster and stronger than in unexposed people. It takes 28+ days and a second dose for the unexposed group to approach the titers seen in the group who already had Covid, and they still don't quite get there. Most notably, even those previously infected people with ~0 titers at baseline rapidly developed high levels of antibodies at 5-8 days after vaccination. It's a small group, but the rapid nature of the response is telling. This data is clear that the infected people had a rapid, robust immune response to vaccination. It cannot tell you what you're trying to infer -- that the vaccination itself increased the immune response. To determine that, you'd need to do some other experiment.
  - Pyramus 5y ago
    I don't follow your argumentation - why would extremely high antibody titres not almost certainly result in a better immune response? On the contrary, from all that we know today, wouldn't we expect people with high IgA titres to even develop neutralizing immunity, at least in the weeks after titres peak?

nradov 5y ago

Higher antibody levels don't necessarily mean a lower risk of disease. While that's possible it remains unproven. There's more to the immune system than just circulating antibodies.