Aren't there currently 3 different vaccines near release? I'd heard 2 (Pzicer and Moderna) vaccines only prevent the immunized from being ill - they don't break the transmission chain, in fact relieving a carrier of any symptoms and leaving them as an active source of spread.
Is this just misinformation, in an age of questionable sources or is there something to the claims that the AstraZeneca provides a better layer of protection for society around those that do get immunized with that particular vaccine?
I know that if the claims that the Pzifer and Moderna vaccines only immunize a person against the symptoms (and illness) but leave them as a viable carrier, we're about to face massive challenges keeping people respecting anything remotely COVID-19 protocols alive.
I know enough people first-hand that seem to believe being flu-vaccined means they don't need to show caution, I'd anticipate many Covid vaccined people stop respecting the protocols entirely - BeCaUsE Im ImMuNe.
I think the different manufacturers have different markets they will be targeting. I’m not sure we are going to be shopping for our choice of vaccine in the USA, at least not initially.
I’ll tell you the main differences that I understand.
- AstraZeneca uses an adenovirus based vaccine, an older technology. The results of their effectiveness is not totally clear. Apparently there was a dosing error and they have two different sets of results. So the efficacy for preventing symptomatic Covid was between 62% and 9o%. But it’s more stable to transport and requires less refrigeration. This vaccine may be a good option for some developing countries, although it appears to be less effective than the other two you mentioned. There is a little criticism about how they’ve presented their data, so maybe the efficacy will be more clear later.
- I’m going to lump the Pfizer and Moderna vaccines together for a moment. They showed similar efficacy, about 95% for preventing symptomatic Covid. The issue with the mRNA as far as I can tell is that it’s got more narrow requirements for stability for transport and storing the vaccine. It has nothing to do with concerns about how it works in the body. More careful refrigeration is necessary, and the concern is that vaccine distributed in large numbers might create challenges if that is not observed carefully.
- I’m trying to understand your question about the mRNA vaccine leading to carrier status, but I can’t figure out where that is coming from. The difference between the adenovirus technique and the mRNA technique is in how the proteins are presented to the body. The vaccine delivers proteins that look like parts of the Covid virus, and the person’s immune system recognizes it as foreign, and creates antibodies to patrol for and recognize Covid. The immune system is then primed for fighting a later exposure to Covid.
With the adenovirus technique, proteins from Covid are inserted into a different virus (adenovirus), one that is intentionally easy for your immune system to defeat. The body learns to recognize the Covid proteins (antigens) and produces antibodies ready to fight it.
With the mRNA vaccines, the messenger RNA is presented to the person via the vaccine. mRNA is a template/code the body can read to translate (build) a corresponding protein. So the mRNA is telling the recipient’s body how to make the protein....protein that is the same found in Covid and that can be recognized later. The body goes through the same process of producing antibodies against the protein. Same end process, but two different ways to get the protein/antigen where it needs to be to induce an immune reaction.
There’s nothing about this process that would result in a different kind of immune response or a different immunity status (carrier? status?). The biggest risk with the mRNA vaccine is careless handling and inoculating people with a product that has “spoiled” and isn’t effective because it wasn’t refrigerated correctly.
I suspect AstraZeneca’s vaccine is going to be delayed a bit because of concerns over inadequate effectiveness. They accidentally gave 1/2 strength doses followed by full dose 2nd injection. That had 90% efficacy. When they did the correct full dose both injections, they got 62% efficacy. They did some statistical sleight of hand and combined the results to get 70% or something in between. But there is no explanation for why the accidental dose was more effective. Competing with other vaccines that are performing better and ready now, there is a lot of pressure.
I don’t know where these ‘concerns’ are originating, but I can recognize that this is a huge stakes financial endeavor. There will be winners and losers among the vaccine developers. It’s easy to see motivation to cast doubt on a competitor’s vaccine. Maybe that’s cynical, but it’s an explanation.