This is an excellent overview of the complexity of mRNA vaccine manufacturing.

An mRNA batch currently takes 110 days from start-finish.

“Traditional” vaccines (recombinant, vectored, inactivated) can take months longer. 1/

@eweise @kweintraub…
More about the complexity of "traditional" vaccine approaches below.

These timelines assume the process has been "scaled up" and everything is in place & ready to go: facility, equipment, raw materials, etc. Unexpected issues can add weeks or months. 2/

Here’s a good reference on #vaccine #manufacturing from several colleagues for those interested in learning more. 3/…
Many thanks to @eweise @kweintraub @USATODAY for writing this story. Much-needed insight when the spotlight is on global supply. 4/

h/t @Merz @jonemo…

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More from @rvenkayya

8 Feb
THREAD: Vaccine Escape

As variants spread and #vaccines are deployed, we’re not sequencing enough to keep up w/the virus.

As a stopgap, we should sequence viruses from every vaccinated person who develops #COVID to identify vaccine escape mutations. 1/…
We call these “vaccine breakthroughs,” and we’ll see more of them as the B.1.351 and P.1 variants spread. Sequencing all breakthrough viruses will help us to track those variants and identify new mutations that might contribute to vaccine escape. 2/
The European CDC (@ECDC_EU) advised Member States do this in their risk assessment in January. 3/
Read 11 tweets
1 Feb
THREAD: Vaccine Manufacturing

Back in October, I said the Warp Speed timelines were extraordinarily optimistic given the inherent risks of vaccine development, manufacturing and distribution. All of those risks and others have materialized. 1/
Much of the risk is in "scaling up" production to produce large volumes of vaccine in a facility, and “scaling out” to manufacturing partners to expand capacity. This thread is about vaccine manufacturing and the challenges we’ll continue to face. 2/
This article from @lizszabo & colleagues is one of the few I've seen that attempts to capture the complexity and risk of manufacturing and explain why supply bottlenecks can't be resolved overnight. 3/ @SJTribble @ArthurAllen202 @JayHancock1 @KHNews…
Read 16 tweets
29 Jan
In light of the exciting & sobering news from @Novavax and @JNJNews, some thoughts on implications for future vaccine development.

As I've said, the Ph3 trials will provide the highest-quality data on vaccine efficacy against the new variants. 1/
Multiple lines of evidence strongly suggest mutations in B.1.351 confer some escape from natural and vaccine immunity.

Unless shown otherwise in efficacy/effectiveness studies, we should assume this is a class effect for all spike-targeting vaccines. 2/
The good news is we're likely to see higher levels of vaccine efficacy against variant-associated severe disease and death. J&J has provided the first evidence of this in their press release (insufficient severe dz in the Novavax interim analysis). 3/
Read 8 tweets
6 Jan
@BhadeliaMD @kavitapmd @ashishkjha @ASlavitt @RanuDhillon @RebeccaKatz5 Manufacturing partnerships are necessary for any company to ramp up manufacturing of #COVID vaccines, since no company has enough capacity to meet the world’s needs. Nearly all vaccines in late-stage trials have partnerships in place for this purpose. 1/ 🧵
@BhadeliaMD @kavitapmd @ashishkjha @ASlavitt @RanuDhillon @RebeccaKatz5 .@Novavax is a good example (@AstraZeneca is another). They listed their network of partners when they announced the partnership with @SerumInstIndia, with a goal of manufacturing >2B doses/yr. (@TakedaPharma is one of those partners.) 2/…
@BhadeliaMD @kavitapmd @ashishkjha @ASlavitt @RanuDhillon @RebeccaKatz5 @Novavax @AstraZeneca @SerumInstIndia @TakedaPharma But it would be hard to quickly expand supply through new partnerships for several reasons:

TIMELINES: Depending on maturity and complexity of the process and partner capabilities, it takes a *minimum* of several months to transfer manufacturing to a new partner & facility. 3/
Read 8 tweets
3 Jan
I created a simple table to illustrate the individual impact of the "flexible second dose timing" now recommended in the UK.

Coincidentally, @bob_wachter & @ashishkjha just tackled the US policy question in this important piece. 1/
I based this on recent statements from the UK chief medical officers, JCVI, and what we know from prior vaccine development. 2/


UK Chief Medical Officer (CMO) statement:…

CMO letter to the profession:…
This table and thread focuses on the AZ vaccine, where more data on a delayed second dose is available than with the Pfizer vaccine. It is not intended to address questions about single-dose regimens or mix & match approaches. 3/
Read 18 tweets
1 Jan
There’s much debate around the UK's recommended use of the AZ vaccine with a two-dose schedule and flexible timing of second dose. Some thoughts on the AZ recommendation (not Pfizer) based on available data with refs to some excellent threads. 1/
UK’s MHRA and JCVI are highly-experienced in vaccine assessments and recommendations, and they've surely weighed the benefits & risks of this recommendation carefully. That said, it would be good to see all the data underpinning their recommendation. 2/
In general, vaccines should be taken on a schedule tested in an efficacy trial. But it wasn’t possible to conduct the typical dose and schedule optimization prior to these Ph3 trials, and those trials provided valuable data to inform these recommendations. 3/
Read 14 tweets

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