Just listened to a fascinating webinar by @ShabirMadh presenting the results from Novavax trial in South Africa and UK.
So will turn this into a brief thread to give some context on what we know so far and what the trial results (probably) mean: https://twitter.com/kakape/status/1354900984993083392

First of all, this vaccine uses a more traditional approach than the mRNA vaccines we have been talking about a lot: It essentially consists of particles studded with the crucial spike protein plus an adjuvant to induce a potent immune response.

The study: This was a phase 2 study with just over 4400 participants and initially designed to look at HIV- people only.
@ShabirMadh says they had “ to really work hard to get Novavax and everyone else to agree to do a sample of HIV-infected individuals”, which is crucial in SA.

The results:
Here is a slide with the main results on preventing #covid19.


Only HIV- participants: 60,1% (19,9% - 80,1%)

Incl. HIV+ participants: 49,4% (6,1% - 72,8%)

Note that samples from 27 patients were sequenced, 25 of those were the variant 501Y.V2

Two important caveats here:
1. @ShabirMadh warned against reading too much into HIV+ results, after all these were only about 150 people, so a single case can change the results. “I would ignore any mention of efficacy or lack of efficacy in the HIV positive group”, he says.

2. There were very few cases of severe #covid19 in the trial and the ones that occurred were in the placebo group.
That’s good.
BUT: As @ShabirMadh said: “We don't have a readout for efficacy against severe disease. The study is not powered to address that."

Upshot:
Glenda Gray and @ShabirMadh agreed that if vaccine efficacy is 60% that is still important.
Gray: “Even a 50% reduction in mild, moderate or severe disease is an important both public health and an individual health benefit.”
(50% is also cutoff defined by WHO, FDA, etc.)

So why did I say this was news I did not want to see?
It suggests that the variant 501Y.V2 is having more of an impact on immunity than many researchers I have talked to were thinking/hoping.
Notably this goes for natural and vaccine-induced immunity.

Natural immunity:
This was maybe the worst bit of news buried here.
In the placebo group there were previously infected people and people that had not been infected.
In the trial both groups ended up getting #covid19 with the same likelihood: 2%.

"What this basically tells us, unfortunately, is that past infection with the earlier variants of the virus in South Africa does not protect against #COVID19”, says @ShabirMadh.
It may protect against severe disease though. Important to figure that out now.

Vaccine-induced immunity:
These data further increase worries that the virus has the capacity to evolve in a way that will make vaccines less efficient.
The writing has been on the wall. Won’t go into that now, but I wrote about this two weeks ago here: https://www.sciencemag.org/news/2021/01/new-coronavirus-variants-could-cause-more-reinfections-require-updated-vaccines

One big question now is: What does this mean for other vaccines? Will AstraZeneca vaccine for instance still have enough of an efficacy against 501Y.V2?
(Results from an ongoing AZ trial in South Africa are likely to be shared within a week, @ShabirMadh says.)

The good news: Vaccinemakers are adapting.
Moderna is producing a booster shot.
Novavax is working on a bivalent vaccine (see slide).
And that, to end on a positive note, is exactly what I want to see.

(Which is why I wrote about it earlier this week: https://www.sciencemag.org/news/2021/01/vaccine-20-moderna-and-other-companies-plan-tweaks-would-protect-against-new)

One last thing (and you must be sick of hearing this from me by now):
We need to reduce transmission.
We need to stop behaving as if vaccines alone will solve things.
Vaccines can be incredibly powerful, but come on people, even the Hulk needs the other Avengers sometimes.