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Vaccine

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madires:

--- Quote from: Circlotron on March 17, 2021, 11:40:43 pm ---I wonder what would happen if you got the first dose of one brand of vaccine and the second does of a different brand? Would it still work? Would it cause any harm?

--- End quote ---

AFAIK, someone is performing a study about combining two different viral vector vaccines. BTW, one vaccine is single-shot (Johnson & Johnson).

jpanhalt:
That question has been asked often.  First, the J&J vaccine is a viral vector vaccine that uses a replication defective adenovirus. Moderna and Pfizer vaccines do not use a viral vector.  They use synthetic liposomes.  The latter two vaccines are quite similar and seem to differ mostly in the liposome. 

Some experts have opined that little harm would be expected by crossing between those two vaccines; however, since such studies have not been completed, no agency of which I am aware has approved doing that.   Even under emergency release approval, one must still comply with the conditions of approval, unless you have an approved research study.

Zero999:
I doubt there would be any harm caused by mixing vaccines, so long as there's sufficient gap between doeses. If there was, then previously infected people would be at greater risk of harm by the vaccine and so far that doesn't seem to be the case, other than an increased incidence of side effects.

It's equally likely mixing vaccines could improve immunity to a greater range of strains, as the immune system will be exposed to different antigens, in each vaccine. On the other hand there isn't the reinforcement effect of being exposed to the same antigen again, which coulld make it less effective. Studies need to be done for each vaccine, before considering such an approach.

JohnnyMalaria:

--- Quote from: jpanhalt on March 18, 2021, 10:55:13 am ---That question has been asked often.  First, the J&J vaccine is a viral vector vaccine that uses a replication defective adenovirus. Moderna and Pfizer vaccines do not use a viral vector.  They use synthetic liposomes.  The latter two vaccines are quite similar and seem to differ mostly in the liposome. 

--- End quote ---

The liposomal part is just a vehicle for the mRNA that protects the mRNA and enables it to survive the journey to into our cells. Once there, our cells use the genetic information encoded in the mRNA to synthesize proteins identical to those made by the virus. By choosing the correct protein to be made, it can trigger our immune response as if it were the virus itself that was present. The Moderna and Pfizer vaccines are not the same when it come to the mRNA but the concept is the same.

The stability of the liposome is important and a challenge. I worked on similar products about 10 years ago. I suspect Pfizer's difficulties with storage temperature lie with the structure of the liposome and the fact that Pfizer hadn't generated any data to support storage at less extreme temperatures. This has changed.

Stray Electron:

--- Quote from: gnuarm on March 18, 2021, 12:28:05 am ---

I'm wondering how long it will be before there is a mass shooting at a vaccination site.  Just when you thought you were safe...

--- End quote ---

   I sort of doubt that that would happen, at least on it's own. All of the vaccine sights that I've seen are well manned by the police in order to keep order and prevent people from jumping in line preventing traffic jams, etc.  There are also usually dozens of paramedics and off duty police there to watch for possible allergic reactions as well.  Hell, some of the vaccine sites in the US are even being operated by active duty US Army personnel.

    But now that you're brought up the idea, it would be too surprising if someone read it and decided to do as you suggested, just for the sheer notoriety of it. Just like the copy-cat school shootings, people see one on the news and then decide that they want to be infamous too and ......

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