I was under the same impression, that the vaccine doses were being made and would be thrown away if the clinical trials showed less than 50% effectiveness.

I can only guess that the vaccine factories have had delays.

There is an earlier post in this long thread about Bill Gates funding the construction of factories, only some of which by chance would have the equipment to produce the effective vaccines.

The other factories would be written off as “acceptable wasted money” to ensure speed.

This is kinda like the three different hugely expensive factories built to produce an atomic bomb during WW-II, two at Oak Ridge and one at Hanford Washington.