Thread by @erlichya

@sigallab did a fantastic job in framing the Abs response to Omicron. But his manuscript actually makes make me a bit concerned and I don't find the results encouraging. Let's dive in a short thread 🧵👇

https://twitter.com/erlichya/status/1475697014818099200

Just a reminder, the Omicron and the Delta are highly diverged from each other compared to the ancestral strain, which serves as the basis for the vaccine.

@sigallab enrolled 15 individuals who were infected by Omicron. Four people were vaccinated with J&J, 3 people with Pfizer, 6 were not vaxxed, 2 had no Ab response and were excluded from the study. These 13people were followed for ~2weeks.

Clearly, all 13 people who did develop antibodies showed improved response against Omicron 2 weeks later. Makes sense.

But can antibodies against Omicron neutralize Delta?
Well that depends. Vaxxed (green) showed also better response against Delta, which also makes sense. They probably mounted mostly their vaccine-based Ab repertoire that works well against Delta. But...

Look only at the unvaxxed individuals with a detectable Ct value at admission (yellow) at the same graph (sorry for my poor photoshop skills). They have a relatively weak response against Delta following Omicron infection. (warning: small dataset)

Now, I see antivaxxer and lay media echoing this simplistic message 🤦‍♂️. At best, O is like another booster for vaxxed and WILL tax the health of some of them. For unvaxxed, it is not a vaccine substitute, since Delta response is likely to be inadequate.

https://twitter.com/sigallab/status/1475584495214546947

Quite the opposite, I am actually more worried. Now we have two strains that *preliminary data* suggest that can elicit Abs repertoire that DON'T cross-neutralize well (without a vaccine). These are not good news.
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