It is interesting that they are reporting a variable response from two different starting doses. Will bet there are some cellular immunologists scratching their heads over this one. It seems likely that they knew this was possible from animal studies conducted before the human trials started - why else would they alter the initial dosage form? None of the other vaccines have done so, but it appears two shots will be required for most of them.
Still, obtaining yet another vaccine which can be produced in large quantities with at least 90% effectiveness should, with other vaccines, help shut down the global spread and replication of the virus sooner, rather than later. This is particularly true of the Oxford vaccine, which can be used just about everywhere in the world due to its very high stability compared with others reported.
Some people still do not seem to understand that stopping the virus with a vaccine means that you prevent it from replicating, and thereby prevent it from further mutating. Since other strains of this virus have been shown to result in more lethal infections, it is only logical to stop the spread and mutations of this virus as soon as possible. Now this is even more important since its has also been shown to infect other species, like mink and raccoon dogs. They too will permit the virus to mutate, possibly resulting in more virulent strains.
Vaccines will shut down the virus faster than any other attempts to minimize its spread, which clearly isn't working anyway.