As a note, I tried that strategy (with a limited resources 'game') and it wasn't competitive. We played with a full player count.
Issues: * It takes several turns to buy all the vaccines. * In the first turn, you will probably split the 'buys' * In the second turn, others will note what you did - you will split again - and they will buy some. * In the tird turn, you might buy out the market but now you are 3 turns behind. Also, others will sell their non-vaccinated pigs... loosing some in the fourth and being annoyed.
The other players' loss of a few piglets didn't overcome the early acceleration of their farm. I did get a few bad pairings when I matched choices with several others. In a group of equivalent players, three were ahead of me - the mental adjustment was interesting and if there were 'fewer' resources in the pool this strategy might be valid.