The return of vaccine Monday, but maybe one of the last placebo-controlled trial results. In their large US/Mexico trial, Novavax confirms the excellent result seen in an earlier UK trial. This includes efficacy against the circulating alpha (UK) variant.
The two dose protein subunit vaccine can be stored at refrigerated temperatures and is cheaper to produce. The company will apply for an EUA in the third quarter of 2021, as they need more time to validate the manufacturing process.
It’s unclear what the market in the US will look like in late 2020, but there is enormous global need. Efficacy against variants not widely circulating during the trial is also unclear. A Phase 2b trial in South Africa showed some drop, but with a wide confidence interval.
*Market in late 2021. What is time?
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A text from a colleague: "Ok how on earth has Twitter decided that we know VE against variants?" 🤔
Twitter does love certainty! But better to think about VE against variants in terms of likely ranges rather than precise estimates. So how do make these assessments? A thread.
Sometimes we have randomized clinical trial data, like J&J Ensemble trial in South Africa and South America. But often we are assembling data from disparate (and imperfect) sources... nejm.org/doi/full/10.10…
Source 1: Data from immunoassays. We can look at neutralizing antibodies against different vaccines and assume this roughly correlates with VE. But we are still characterizing these relationships, and these assays do not capture cell-mediated immunity. nature.com/articles/s4159…
I hope people are aware of the enormous added value of HIV clinical trial networks. Groups who have been working on vaccine & treatment trials for decades leapt into action to work on COVID. OWS vaccine trials directly benefitted from the expertise of these groups. A big success!
There's a lot we can learn from this experience about:
- Leveraging existing networks
- Coordination between companies and researchers to standardize protocols across trials
- Using a centralized DSMB for oversight
- Pooling data, as planned for immune correlates analysis
A recent pub with more info:
"A single 11-member DSMB monitors all government-funded trials to ensure coordinated oversight, promote harmonized designs, and allow shared insights related to safety across trials." @SteveJoffe et al. academic.oup.com/jid/advance-ar…
How will we know if we need COVID vaccine boosters?
If we observe that: (1) Vaccine protection wanes over time. (2) New immune escape variants emerge, resulting in a vaccine-strain mismatch.
These are distinct reasons. We can imagine how we would distinguish these in the data.
(1) Immunity wanes over time.
We would see that:
- Breakthrough cases occur most frequently in people who were vaccinated longest ago.
- These breakthrough cases include all types of strains.
(2) New immune escape variants emerge.
We would see that:
- Breakthrough cases are similarly common in people vaccinated recently and vaccinated longest ago.
- Breakthrough cases are disproportionately of the new variant type.
In the US, we're rapidly building immunity thanks to highly effective vaccines. Cases have been quickly dropping. What might we expect in the coming months?
A few tweets on how I think about our patchwork of outbreaks... 1/6
Immunity will not be spread evenly throughout the population. While we track vaccination coverage at the national or state level, infectious disease dynamics are inherently local. Pockets of unvaccinated people who have not previously been infected will exist. 2/6
These pockets with lower immunity will remain at risk for outbreaks. While populations with high immunity may no longer be at risk for large outbreaks, movement between areas (and from across the globe) will lead to regular re-introductions and onward cases. 3/6
Yes. A vaccinated person is less likely to transmit because they are less likely to ever be infected. At a population-level, this translates to reduced transmission. cdc.gov/mmwr/volumes/7…
2) But if a vaccinated person gets infected, are they less infectious?
This is hazier. Maybe they have lower viral load, shorter duration of infection. Maybe virus is contained to the nose only. But less infectious does not equal non-infectious.
A few replies mentioning the UK household study estimating 50% reduction in infectiousness. Studies of close contacts can provide valuable real-world evidence, and estimates from these studies will accrue over time. khub.net/documents/1359…
“Everyone believes in coordination, but no one wants to be coordinated.”
In today’s @WHO forum, Sir Michael Jacobs (@RoyalFreeNHS) with a call to action to improve collaboration for therapeutics research. 1/4
He provides a successful example of three large-scale platform trials collaborating to harmonize protocols for antithrombotics. Data are more valuable when they can be combined and compared. 2/4
He provides another example of countries having committees to prioritize new drugs for trials. Within the last few months, the committees have realized the advantage of sharing briefing documents and resources. Reduces duplication of effort and minimizes risk of omission. 3/4