Thread by @profshanecrotty

The AstraZeneca/Oxford (AZ) COVID vaccine (ChAdOx) results in South Africa are concerning. 🧵

* The AZ vaccine had 75% efficacy against mild COVID through October 2020.

* But only 22% efficacy more recently, with the SA variant  (aka B1351 or 501Y.V2)

facebook.com/HealthZA/video…

Penny Moore and Alex Sigal and colleagues now report on antibodies from AZ ChAdOx vaccinated people, and there was a dramatic loss of function against the B1351 variant. It appears to be more than a 20x reduction. A complete loss of neutralization in most individuals (~80%).

First, what to think of the antibody neutralization loss?

It is much steeper than reported by multiple groups elsewhere for COVID19 cases or other COVID vaccines. Multiple labs reported ~2x drop in neutralization of B1351 or related virus, with antibodies from vaccinated people

New data from Oxford suggests that the AZ vaccine is uncommonly poor at neutralizing the UK variant (B117), seemingly in contrast to some other COVID vaccines.

https://twitter.com/profshanecrotty/status/1358800667180113920?s=20

However, Penny Moore lab data for B1351 neutralization was also ~8-fold down for COVID19 cases (range = no change to 64x) .
biorxiv.org/content/10.110…

Ho and colleagues were another group to report relatively large drops in neutralizing antibody potency against B1351. Nevertheless, neutralization was detectable, and  Moderna and Pfizer vaccinees did at least as well as COVID19 cases.
biorxiv.org/content/10.110…

Circling back to this:
New data from Oxford suggests that the AZ vaccine is uncommonly poor at neutralizing the UK variant (B117), seemingly in contrast to some other COVID vaccines.

https://twitter.com/profshanecrotty/status/1358800667180113920?s=20

Verbally, SA scientists seem to be confirming this:

https://twitter.com/kakape/status/1358822602333171722?s=20

So, we don't have enough data to say anything for certain about differential changes in neutralization of variants by different COVID vaccines, but clearly scientists in South Africa are working intensively on this.

What does this mean for COVID immunity more broadly?

We don't have enough information to say.

Clinical efficacy against mild COVID is substantially reduced against B1351 for the AZ and Novavax vaccines, clinical efficacy against moderate COVID is reduced for the J&J vaccine (comparing between results in different countries).

All of those are based on press releases / press conferences. Beyond that, we really need more information still. It is important is see if the AZ vaccine will still protect against more severe disease (including hospitalizations and deaths) with B1351.

@ProfAbdoolKarim has a very good summary of the status that I fully agree with. [starting at about minute 1:21:00]
facebook.com/HealthZA/video…

And, I must say, there was very impressive science and thoughtful conclusions reported in this South African COVID-19 vaccine press conference. Outstanding job by leaders in South African science and heath ministry.
@DrZweliMkhize @ProfAbdoolKarim

which is not a surprise to those of us who have worked in the HIV vaccine field!

also on YouTube: