Roger Seheult's outstanding visual analysis — of Pfizer, Moderna and AstraZeneca COVID vaccines

© 2020 Peter Free

 

26 November 2020

 

 

Making biomedicine simple to understand is a rare talent

 

Medicine professor Roger Seheult is consistently brilliant at it.

 

 

I mention him today . . .

 

. . . for his recent video-pictorial analysis of the press-released differences among the (still being tested) Pfizer, Moderna and AstraZeneca COVID vaccines.

 

See:

 

 

MedCram - Medical Lectures Explained Clearly, Coronavirus Update 118: AstraZeneca DNA COVID 19 Vaccine Explained (vs. Pfizer / BioNTech, Moderna), YouTube (24 November 2020)

 

 

After watching Seheult's MedCram video . . .

 

. . . those of you who are scientifically inclined may notice the (undiscussed) potential risk differences between the mRNA versus DNA (itself packaged inside a chimpanzee adenovirus) approaches.

 

Would you favor a direct mRNA process that generates immune reaction-provoking SARS-CoV-2 spike protein products (for our bodies to make themselves immune to) inside the cell's cytoplasm, via routine ribosomal translation?

 

Or would you prefer delivering modified DNA (contained inside an altered chimpanzee adenovirus) into the cell's nucleus — so as to (only then) secondarily generate roughly the same mRNA product spike proteins in the cytoplasm?

 

The risks for the DNA approach appear to be higher:

 

 

What happens if the modified adenovirus itself does not act as anticipated — even with its clipped-out chimpanzee virus replication coding — and generates an unexpectedly widespread illness or reaction of its own?

 

Or, similarly, if low — but nevertheless noticeable — numbers of test subjects' bodies have atypical reactions just to the modified adenovirus?

 

Or if something subtle, and initially undetected, goes wrong with manufacturing the altered adenovirus and its contents?

 

Or if the adenovirus itself is fine, but its inserted DNA does not work inside some recipients' cell nuclei exactly as one had expected it to?

 

And so on.

 

The more steps in vaccine production that are required, the seemingly more chances to badly screw something up.

 

 

Why would AstraZeneca adopt this potentially more problematic, though longer proven, vaccine-delivery avenue?

 

Recall that the reputational and financial risks of falling on one's face during vaccine trials are significant.

 

One answer — aside from the adenovirus DNA delivery being a reasonably long-demonstrated interventional technique — may be AstraZeneca's very much superior vaccine logistics.

 

Dr. Seheult points out that AstraZeneca claims that its vaccine can be stored at ordinary refrigerator temperatures. If true, that's a potentially game-winning attribute in my view.

 

Transport and storage logistics are a huge concern with any vaccine.

 

So far, I have not been impressed with Moderna and especially Pfizer's extreme cold storage requirements. Those represent infrastructural problems just waiting to happen across most of the world, including the United States.

 

 

Statistically astute viewers may also have wondered about . . .

 

. . . AstraZeneca's half-dose mistake (during its first United Kingdom vaccine test administration) resulting in a purported rise from 62 percent to 90 percent effectiveness.

 

This favorable result, I would tentatively — for caution's sake — attribute to the UK's only 3,000 subject testing, as compared to the 9,000 in the Brazilian arm.

 

As The BMJ wrote in a late-October editorial, none of the COVID vaccines' testing is numerically stout enough to detect differences of the comparatively low magnitude (in outcomes) that SARS-CoV-2 has displayed.

 

Big test numbers are necessary to detect statistically rarer (presumably genetically caused and demographic) differences.

 

AstraZeneca's reported rise in efficacy from the two full doses' 62 percent result — to the inadvertent initial half-dose UK variant's 90 percent — may be an illusion generated by a test pool consisting of statistically too few UK subjects.

 

AstraZeneca is reportedly sorting this conundrum now, by expanding vaccine subject numbers, so as to investigate both the half and full-dose methods.

 

 

The moral? — Knowing how bio-manipulated vaccines are designed . . .

 

. .  and roughly what potential risks varying approaches involve, should make a difference to reasonably knowledgeable recipients.

 

Kudos to Professor Seheult.

 

Condensing molecular biology in the pictorial, understandable fashion that he regularly does, is challenging and helpful.