No oops involved. It was entirely predictable to anyone scientifically or medically educated that we would need more vaccinations in the first years to protect against and entirely new virus that our immune systems had never seen before, using newly developed vaccines. In coming years the vaccines will be tweaked according to the dominant strains, exactly like the flu vaccines are, and I fully expect that in a year or so we will be offered an annual covid shot, just like the annual flu vaccine. It will also settle down to be advised mainly for older people or people with compromised immune systems. Exactly like flu. For most people, it will be a mild annual few days in bed, just like flu, as this new coronaviris settles down to be, basically, another cold virus, just like all the other colds that we get now that originally wiped out loads of cavepeople or whatever.
Entirely predictable that more doses would be required in the first year or two, especially as we are reacting to new variants that aren't year predictable, as it's only been around for a couple of years. Eventually, the clever scientists will be able to predict the dominant strains and prepare the annual covid shot in advance, with varying annual accuracy, just like flu.
The latest antivax thing of going on about oh we need 3 shots a year now and they never said that from the beginning is laughable, it really is. Any intelligent person can see that were still (in year 2) in the reactive stage of a response to this completely new virus and that, eventually, it will settle down into a nasty winter respiratory virus that can overload the NHS and will kill some older or weaker people every year. Entirely predictable and understandable. No oops involved.