Because vaccines are in short supply. The choice isn't AZ+Moderna+JJ+PB vs Moderna+JJ+PB. the real choice today is AZ+Moderna+JJ+PB+NOTHING vs Moderna+JJ+PB+NOTHING, with the size of nothing being larger in the second case.
So really it is c: you vaccinate everyone with whatever you can get your hands on. Once everyone has had some vaccine you look at data of what is working and give everyone with a less effective vaccine an additional dose of whatever works - which will probably be a new vaccine that doesn't exist yet!
Don't forget that mutations are continuous. We might be looking at another mutation in 3 months as supply catches up that evades vaccines in a completely new way.
> give everyone with a less effective vaccine an additional dose of whatever works - which will probably be a new vaccine that doesn't exist yet!
I would be careful about assuming that's an option. The vaccines have been tested individually, but have not been tested together. It's not out of the realm of possibility that getting some combination triggers some kind of immune reaction or something else.
> Don't forget that mutations are continuous. We might be looking at another mutation in 3 months as supply catches up that evades vaccines in a completely new way.
This is, sadly, a reason for poorer countries to delay vaccination. If there's going to be a mutation that evades this vaccine, and you can only afford one round of vaccines for everyone, you'd be better off waiting for the vaccine that prevents both.
Based on the last article about this, SA doesn't have the money to do 2 rounds of vaccines. A lot of the money was spent suspiciously, but now funding is limited. It seems that anyone who gets a subpar vaccine is just going to be stuck with subpar coverage.
That works both ways: the sooner the alternatives are available in adequate quantities, the less the harm (if there is anything to be concerned about) of continuing to use the AZ vaccine at least until then.
Fair point, but the others won't be available in adequate quantities anytime soon. I'm not sure where SA stacks up, but nobody is getting adequate quantities before this summer at best.
So really it is c: you vaccinate everyone with whatever you can get your hands on. Once everyone has had some vaccine you look at data of what is working and give everyone with a less effective vaccine an additional dose of whatever works - which will probably be a new vaccine that doesn't exist yet!
Don't forget that mutations are continuous. We might be looking at another mutation in 3 months as supply catches up that evades vaccines in a completely new way.