There seems to be a number of problems with this system, not least that they need your money in order to achieve the results in the first place.

One could even imagine an entirely for-profit firm that gives free vaccines to poor third-world kids. Initial funding could come from the firm's investors or loans (i.e. the same ways all for-profit firms get funding). A charitable person inks a contract for "delivery" of 10,000 vaccinated kids for a given amount of money. The firm has an incentive to deliver this efficiently and quickly, so they can pocket the difference. Competition between firms then keeps the profit margins reasonable.

The main disadvantage is that non-profit groups would have huge tax advantages over for-profit firms.