RadVac Commercial Antibody Test Results

post by johnswentworth · 2021-02-26T18:04:09.171Z · LW · GW · 30 comments

Contents

  How I'm Updating
  Next Steps
None
30 comments

Background: Making Vaccine [LW · GW]

Results are in from the commercial antibody tests. Both my girlfriend and I came back negative - the test did not detect any Spike antibody response in the blood. This post will talk about how I'm updating based on these results, and the next steps.

Here's our timeline so far; more info on the vaccine is in the original post [LW · GW] and the radvac whitepaper:

• We've taken five doses, spaced apart weekly (on Tuesdays).
• The first three doses only included six of the nine peptides, due to delays from the manufacturer. (Spike 660, Spike 1145, and Orf1 5471T were the three missing.)

The blood draw for this test took place the day after the fifth dose. I expect this is too soon to notice significant impact from the last two doses; vaccines in general seem to typically take 2-3 weeks to kick in, and that is my expectation for this one as well. (Also, it was an "IgG antibody test", and WebMD says these antibodies typically take about 2 weeks to show up after covid symptoms show from an actual infection.) This is intended to mainly be a test of the first three doses.

The test apparently used the "DiaSorin Liaison(R) SARS-CoV-2 S1/S2 IgG assay" (I didn't know this until the results came in). According to the FDA, it has about 92% sensitivity and 99% specificity. The "S1/S2" part indicates that it's testing for response to the S1 and S2 subunits of the spike protein - together, these are essentially the whole spike protein.

Important thing to notice: the test was looking for Spike antibodies, and two of our three missing peptides were Spike peptides. Indeed, there were only 3 Spike peptides among the full 9, so with two missing, we only had one Spike peptide in our first three doses. (The rest target other parts of the virus.) So that makes the test significantly less useful than it would otherwise be, and makes me more inclined to get another test in 2-3 weeks when the doses with the other three peptides have had time to kick in. 

How I'm Updating

In the original post, I called this test "searching under the streetlamp". It wasn't super likely to come back positive even assuming the vaccine worked as intended, but it was relatively cheap and easy to run the test, so it was our first check. Given the missing Spike peptides and the test only checking against Spike, it was even more likely to come back negative than I originally estimated.

In Jacob's prediction questions [LW(p) · GW(p)], I gave roughly a 25% chance that a commercial antibody test would pass for most people, given three doses and all 9 peptides. I gave the vaccine about 75% chance of working overall, distributed over several different possible worlds. In this specific scenario, it's clear that the prior on test passing should be even lower.

(Reminder on the possible worlds: the vaccine could induce antibody response in the blood and mucus, only mucus, or not at all. It could induce T-cell response separate from antibody response. It could work sometimes, much like how the first dose of commercial mRNA vaccines tend to work in 75% or 85% of people, and in that case I expect more doses/more time to make it work more often.)

After updating on the results, I'm down to about 60-70% chance of working overall. Unfortunately this test just didn't give us very much information - at least about the vaccine working.

Aside from the test result, we do have one more small piece of information to update on: I was quite congested for 1-2 days after the most recent three doses (and I was generally not congested the rest of the week). That's exactly what we'd expect to see if the vaccine is working as intended, and it's pretty strong evidence that it's doing something. Updating on both that and the test results, I'm at ~70% that it works overall.

Next Steps

There's a few directions to go from here.

First, we can take one more dose with all the peptides included, wait a couple more weeks, and get another test to see if there's a blood antibody response against the Spike protein. That would still be searching under streetlight - it's still cheap and very useful if it passes, but most likely to not pass even if the vaccine works.

We could also specifically look for a commercial test which checks for both Spike and Nucleocapsid antibodies, rather than just Spike, but I expect that to be difficult - those sorts of details are not particularly visible to consumers. Also, it would still most likely be a blood test.

The most interesting direction to go from here is to order an ELISA assay kit and run a test ourselves. Official Best Person Anna Czarnotta suggested a protocol [LW(p) · GW(p)] and gave a bunch of helpful tips on this in the comments on the previous post. This would not require waiting another 2-3 weeks, and would allow us to test mucus directly. It would be a pretty direct test of whether the vaccine works, not a searching-under-the-streetlight test. So that's probably what we'll try next; I need to do some reading to figure out the details. Further results will be posted when they come in.

30 comments

Comments sorted by top scores.