Just for fun, I’ve extracted two figures from a paper reporting on levels of anti-SARS-CoV-2 antibodies to the Spike protein, to give you something to compare your own values to. I am making no attempt to explain the paper from which these figures were extracted, which is basically testing reagents. Nor is any data provided about the level of protection afforded by any particular antibody level. The purpose is simply to provide some reference for where 250 U/mL lies on the scale of antibody levels.
Figure 2 (top) is a plot of anti-spike antibody as measured in units/mL (U/mL) on the Y axis, and the time post-vaccination measured in weeks on the X axis, for 34 individuals who have never tested positive for COVID-19, and who have been vaccinated with the Pfizer vaccine.
The Y axis is plotted on a log scale and you can see that there is a very large range of anti-spike antibody concentrations evident two weeks after the first vaccination, and that following the second vaccination the titers rise significantly in all tested individuals.
The LabCorp semiquantitative assay that is being used in the LLS study (NCT04794387) does not determine antibody levels greater than a 250 U/mL cutoff point which I have marked on the Y axis of the plot. This study which uses a quantitative assay also reports the antibody levels as U/mL which are units based on how much a sample needs to be diluted before antibody binding is no longer detected. A quantitative assay takes longer, uses more reagent, and is thus more expensive.
Figure 1(bottom) is a scatter plot of 3033 serum samples collected from non-vaccinated individuals, some of whom have had COVID-19 in the past and some of whom haven't, comparing the levels of anti-nucleocapsid antibodies to anti-spike antibodies. In this plot anti-spike antibody is again measured as U/mL, this time on the X axis, and anti-nucleocapsid antibodies are plotted on the Y axis, measured by a cut-off index (COI; signal of sample divided by cutoff). The assay for the anti-nucleocapsid antibodies was different, and hence the difference in units. I’ve circled the samples that had ~250 U/mL of anti-spike antibody so that you can compare the value to the vaccinated individuals in Figure 2. Take note that the X and Y axes are both on a log scale and that the red dotted lines show the cut-off levels, ie anything below those lines is considered negative.
GG, this is such an interesting topic. Can you dumb it down for me? 😛 You have a fundamental understanding of these things that’s over my head. I need a “for kids “ version of this.
Jeff, because folks are starting to get results from their LabCorp blood draws as part of their participation in the LLS Clinical Trial NCT04794387, there have been questions raised, particularly about the >250 U/mL value that has shown up on some people’s reports. I posted Figure 2 (the top figure) so that folks could see the range of antibody levels over time when a Quanatitative test is run. Particularly so that they could get a glimpse of what values above the Semi-Quantitative cut-off of 250 U/mL look like in healthy subjects over time. In Figure 2, each dot on the plot represents the antibody titer from a single blood draw. Only antibody to the spike protein was measured.
In Figure 1 (bottom) antibody from the Spike protein and antibody to the nucleocapsid protein were measured. Again, each dot represents data from a single blood draw, but in this case two antibody tests were run and all participants had been diagnosed with, and recovered from, COVID-19. The plot shows that in COVID-19 recovered individuals there are many who’s antibody titer is below the 250 U/mL value.
My antibody level from the LabCorp semi-quantitative anti-spike antibody test was 5.6 U/mL, which I’ve marked on Figure 1. That’s a pretty low amount, but from this plot it is clear that my response to the Moderna vaccine has the potential to give me as much or more protection as many who have have recovered from COVID-19.
Let me know if this makes any sense to you and if not, please don’t hesitate to ask more specific questions.
This is fascinating. I'm just not sure of what we CLL patients.The post vaccination plot tells me that healthy volunteers of working age got a variable response to the first dose, but their Ab values converged at a much higher level (values above 250 can be measured but for the average punter are not recorded?) after the second dose. If the test can be trusted this must reflect the relatively homogeneous healthy immune status of these participants - in contrast to CLL patients.
The post infection group is much larger and more heterogeneous, judging from the wide scatter of the plot. The relationship between spike and nucleocapsid Ab values seems nebulous. Spike 5.6 or 250, in both cases the corresponding NC is a range covering two orders of magnitude.
The test kit that was used to create the above plots was the
Elecsys Anti-SARS-CoV-2 S assay (Ref. # 09289275190) by Roche, which is the same test kit used by LabCorp for semi-quantitative determination of anti-Spike antibodies.(fda.gov/media/144037/download)
Values above the measuring range for the kit are reported as > 250 U/mL. However, if the serum sample is further diluted (the standard kit dilution is 1 to 10) so that the concentration of antibodies is now within the testing range, accurate higher values can be determined. To obtain the higher values in the above plots the serum was further diluted 1 to 10 making the cutoff for an accurate test result 2500 U/mL. If you look carefully at the values reported for antibody levels at 4 & 5 weeks post-vaccination you will see that many values reach the 2500 U/mL cutoff, meaning that if the researchers had made an additional 1 to 10 dilution there would probably have been a greater spread in the vaccine responses. Likely the antibody values are not as homogeneous as they appear in the plots.
And no doubt the results from antibody testing of CLLers will result in a much broader spread. Already we've gotten CLLers reporting no antibody detected to those reporting >250 U/mL. What will be interesting is to see how these values relate to 1. the case histories and 2. the amount of protection, and 3. the changes in antibody titer over time.
You can probably guess that the weather over the past couple of days has been rainy here in Tennessee. Otherwise I'd be out working in the garden. 😉
Well, I hope the Tennessee weather clears up soon. If I was able to travel I might be on my way up Ben Nevis!
I know there are some ongoing studies of responses of immunocompromised patients to vaccination, which should give a consistent basis for analysis and maybe resolve the key variables for CLL patients. e.g. birmingham.ac.uk/news/lates... Similar studies in the USA I guess.
Dear gardening-girl, This is really fantastic extraction of data. i get my free LabCorp blood draw tomorrow morning. My fingers are crossed that I'll have detectable Abs.
Well I’ll be damned, 20 days after my 1st shot (&1day prior to second shot), my blood had a covid spike-specific Antibody level of 142 units! I feel like I won the lottery! The tests was therefore quite positive for response to Prizer’s vaccine, and negative for nucleocapsid antibody indicating I’ve never had a covid infection. Thank you very much to the American Lymphoma and Leukemia Society for your free testing at LabCorp!
Absolutely fantastic! From the plot above it looks like you scored above the median for healthy individuals in the study! So, you were able to join the LLS trial from the Netherlands?
Looking for these graphs, I ran across your profile and noticed a mention of Raynaud's. I'm curious if your MDs linked hyperlymphocytosis to Raynaud's syndrome. My hematologist didn't blink an eye when I told him about I had Raynaud's symptoms at the same time my newly diagnosed CLL progressed slightly (lymphocyte count doubled from 15 to 30). I hadn't had hardly any Raynaud's symptoms in decades, but had them regularly in my youth.
Greetings Tortola2019! Actually it was a rheumatologist who diagnosed my CLL. I'd been suffering from Raynaud's for several months and finally made an appointment with a rheumatologist who found that the cryoglobulin that was causing my symptoms was monoclonal (it formed a single band upon gel electrophoresis) and was therefore Type 1 cryoglobulinemia, suspicious of a lymphoproliferative condition. He ran a Flow Cytometry test and discovered my CD20/CD5 cells, and hence the CLL diagnosis.
Upon treatment, my Raynaud's symptoms, as well as other symptoms, disappear and with each relapse, symptoms reappear. I don't need to get a CBC to know I've relapsed.
If you manage to get your MD to order a cryoglobulin test make certain that your blood is collected in a prewarmed 37 degree tube and is kept at that temperature throughout processing. At one point I had a cryoglobulin test done at MDAnderson. The lab did not follow the proper protocol and the test came back negative. My specialist there was furious that the lab did not know how to run the test.
I just got my test results back today (May 8). My score was over a thousand. I only say that because I wonder if LLS has changed their protocol and now able to detect above 250?
Your the second HU member that recently posted a result over the >250 marker! So it appears LabCorp (or LLS) has changed their scoring. The other member had a score of 2500 per her post a day ago!
Maybe LLS got a bucketful of emails on why the >250 marker as top range shown and decided to change the high end scoring ? I wrote them a couple times on this very issue.
It at least starts to show the true “length” of the scores as yours and the other HU member are around the healthy non-CLLers (2000 or so I hear) for antibodies score. That to me is telling me more about the test data then the lame >250 high end range was.
Good to hear.... and huge congrats you are truly in the “good” in the more than thousand mark! Awesome.
I have contacted LabCorp asking about the change in values being reported for their semi-quantitative spike antibody assay but haven't gotten a response yet.
I’ve contacted LLS 3 times on the scoring issue n got 2 replies so far but they don’t directly answer the >250 scoring question yet. So hoping my 3rd email gets an answer. Interesting it appears they changed scoring G-G though tiny sample finding just 2 HU members recently getting two big actual scores (over a thousand and 2500). Wow! Nice.
Hey there I am one of the other people here on HU who’s results were more (my results stated “ >2500.0” ) I’m wondering if you think something is wrong with our tests or would it more likely be a change in value. You seemed very well versed in this — thank you so much for your explanations!!
I doubt if anything is wrong with the LabCorp assay, but I don't know yet what kind of pressure led LabCorp to make the further 1 to 10 serum dilution required to get readings between 250 and 2500 U/ml. In your case another 1 to 10 serum dilution would allow for quantitation between 2500 and 25000!
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