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Shane Crotty Profile picture
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22 Mar, 4 tweets, 1 min read
It is good to see this AstraZeneca Oxford ChAdOx COVID vaccine efficacy clinical trial report in America. It will be more valuable to see the FDA filing documents when they are ready. Another COVID vaccine success! 🧵

hosted.ap.org/article/a73e71…
79% effective at preventing COVID cases. These results are quite similar to AZ COVID vaccine trial results in the UK (which took a long time to deconvolute).
While the AstraZeneca vaccine works, I don't see myself recommending it to anyone who has access to the Pfizer, Moderna, or J&J (1-dose) COVID vaccines. Almost all of the indications are the Pfizer and Moderna 2-dose RNA vaccines protect better (at least over several months).
And 1-dose J&J protected reasonably against the South Africa variant (B1351) (~64% efficacy) while the AstraZeneca vaccine failed against that variant of greatest concern. Also notable is that 2-dose J&J is still a possibility in the coming months, with stronger immune responses.

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More from @profshanecrotty

Shane Crotty Profile picture
4 Mar
How much immunity do you need to stop COVID? And what about the variants?
Here's the way I am currently thinking about it. Please imagine these models written in crayon. They are not formal, just where my head is at. 🧵
Immunology is complicated, and scientifically proving all mechanisms of protection in humans is somewhere between hard and impossible. But not to say we know nothing. I summarized the scientific knowledge on immunity to SARS2 in this review last month.
doi.org/10.1016/j.cell…
What I have said for the past 20 years (in almost every scientific seminar I give) is: 

The best vaccine is one that elicits high concentrations of neutralizing antibodies and maintains those high amounts forever.
For any antibody neutralization sensitive pathogen.
Read 31 tweets
Shane Crotty Profile picture
3 Mar
The speed of progress to update COVID vaccines is just incredible. Moderna shipped an updated B1351 (South Africa variant) RNA booster vaccine candidate to the American NIH Vaccine Research Center last week for immediate human Phase 1 clinical trial. 🧵

businesswire.com/news/home/2021…
The booster vaccination plan is reasonable, and such a variant booster vaccine could be available quite quickly with an immunogenicity and safety trial.
(/2)
The approach seems likely to elicit high amounts of crossprotective antibodies, based on recent reports of very high antibody responses after 1-dose COVID RNA vaccine immunization of people with previous COVID disease. And the T cell responses will be conserved and boosted.
(/3)
Read 16 tweets
Shane Crotty Profile picture
26 Feb
(iv) Durability of immunological protection against COVID-19 is still unknown for each of these vaccines.
(v) The J&J 1-dose does quite well against the SA variant. That's a big deal! In contrast, the AstraZeneca vaccine appears to have almost no efficacy against that variant (~10% efficacy in confirmed cases).

(vi) Lastly, the J&J vaccine had substantial increases in neutralizing antibodies after two doses (T cells were not reported post-boost).
nejm.org/doi/full/10.10…
Read 6 tweets
Shane Crotty Profile picture
26 Feb
The J&J COVID-19 1-dose vaccine data have been filed with the FDA and are under review there (probably final decision tomorrow).
Here are my thoughts on the J&J 1-dose COVID-19 vaccine, now that the data are public.🧵

(Janssen=J&J = Johnson & Johnson) Vaccine name: Ad26.COV2.S
Executive summary:
🔵 1-dose. Very convenient! And easy to store.
🔵 Essentially 100% protective against death or hospitalization. Very good!
🔵 69% protection against symptomatic COVID-19. Just ok.
🔵 Similar protection against the South Africa variant (72%-->64%). Very good!
The FDA EUA package data are consistent with the statements in the J&J vaccine press release several weeks ago.

Here's my tweet thread from then:
Read 22 tweets
Shane Crotty Profile picture
26 Feb
An important and fascinating long COVID topic, @DanielGriffinMD
🧵
Obviously I can only speculate for now. Actually, let's be really clear:

SPECULATION

IF there is an effect of COVID vaccines on long COVID (I don't want anyone to have unrealistic hopes without there being data from a well-designed clinical study!), the simplest options are:
1. The strength of the vaccine immunization serves to reset a homeostatic baseline to the immune system.

2. Exactly as Akiko said so well:

Read 7 tweets
Shane Crotty Profile picture
26 Feb
Excellent paper on the human B cell response to COVID-19, by the fantastic Laura Walker. 🧵

immunology.sciencemag.org/content/6/56/e…
1,213 human monoclonal antibodies (!), showing substantial affinity maturation of the B cells over time.
A substantial fraction of the Spike-specific response is to RBD. Consistent with other work.
Read 7 tweets

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