Thread by @profshanecrotty

1/ J&J COVID-19 vaccine. Single dose Ad26 (adenoviral).

Another important COVID-19 vaccine success!

Topline J&J vaccine efficacy reported to be 100% against serious cases of COVID-19 more than 28 days after immunization. Those are big!
1/n

bit.ly/3tb7K5d

2/ That includes USA, Latin Amer, and South Africa study sites. It will be important to see more data, because the initial press release was definitely thin on data. But, initial report 72% efficacy against "moderate to severe" disease. That is good for a single dose immunization

3/ The J&J COVID-19 vaccine generated good immune responses in people after one immunization, but there was a substantial boost to the antibody response after a 2nd immunization. A 4x gain. (T cell responses after the 2nd dose were not reported)
nejm.org/doi/10.1056/NE…

4/ So, it is reasonable to expect that a two dose regimen of the J&J COVID vaccine would have significantly higher protection than the one dose. Again, good news.

5/ Probably most notably, they reported "72% in the United States and 57% in South Africa [SA]." In SA, almost all cases now are the "SA variant" (aka 501Y.V2), which has significant evidence of partial immune escape.

6/ (Other people have covered this variant topic extensively, and I will try to make some comments and re-tweet others later today.) One key concern has been whether vaccines would still protect against this SA variant.

7/ A 15% drop in efficacy between "regular" SARS2 and the SA variant (i.e., US clinical trial and SA trial), is actually good news. That is a rather moderate change in efficacy. And, again, this was a single dose of J&J.

8/ That vaccine efficacy of J&J 1-dose against "regular" vs. SA variant is consistent with either:

(i) A decrease in potency of antibodies against the SA variant is modest for J&J vaccine.

(ii) The T cell responses by the J&J vaccine play a big role in protection.
or

9/
(iii) the 'cross protection' against the SA variant is restricted to protection against more serious COVID.

There is no specific data for each of those 3 options. It will be important to get more information on each.

10/ Option 1 would be consistent with recent pre-prints on neutralizing antibody titers in Moderna or Pfizer vaccinees being moderately lower against the SA variant or similar mutants.

11/ Option 2 would be consistent with a range of correlative data indicating CD4 and CD8 T cells have protective roles in COVID-19 (summarized in the review below).
doi.org/10.1016/j.cell…

12/ Also note that the J&J vaccine clinical trials were done during periods of extremely high SARS2 transmission in American and South Africa, with lots of virus around. So (as noted for the Novavax UK result), that is a tough environment for vaccine efficacy.

13/ (i.e., most likely a higher bar for protection than summer transmission in the USA, or anywhere with low level SARS2 transmission).

14/ I am also in full agreement with @EricTopol and others that it will be important to see more of the data to make further conclusions about this vaccine.

https://twitter.com/EricTopol/status/1355240610496565249?s=20

15/ Bottom line, the J&J COVID-19 vaccine is another big win for humanity in the battle against COVID-19.