They have different ways of creating protection for the body: Oxford and Sputnik use the more traditional (proven) method of adapting a virus shell - viral vector.Maybe I’m a bit dim but surely since this is a global crisis if there is a better vaccine out there why isn’t the “recipe” shared with all pharm companies to make it? I’m guessing profit is involved.
These vaccines are cheaper and easier to store, but their effectiveness is still up for analysis. Pfizer and Moderna use a newer and less tested RNA approach.
With this, there are issues with storage limitations (-20C to -70C for example) and the additional cost of each. It's more of a broad approach to try a spectrum,
