Your question implies that there is a time for this to happen, well all the other parts of society that would bring about the proper conditions for this type of situation need to be present first, and we are a long way from that kind of world.
A lot of cost goes into pharmaceuticals, first you have to pay for research and development for new drugs, and there are time limits on exclusive rights, so many drugs can be made by anyone now without having ownership of the patent rights. Next they have their manufacturing costs and distribution. Then they spend a lot of money in the CYA department to pay corporate lawyers and publicists to handle accusations against their drugs, plus the inevitable court costs, fines, or out of court settlements. Then they have to make sure they still have a product by keeping certain things illegal, such as if you were allowed to grow your own opium then painkillers would be worthless, or if certain hallucinogens were available under the supervision of a certified professionals (psychologists, clergy, etc. who have training) then anti-depressants and anxiety medication would be virtually worthless, so they have to pay a lot to lobby against those types of things.
Then when it comes to immunizing the third world, which countries get immunized and who goes first? No matter what they do they will end up with bad blood from potential investors native to X country that is upset. Then there is the possibility that the native population refuses the drugs as they have cultural beliefs against advanced medicine. Lastly and really the more prevalent problem is the elite few of the leading dictatorship or tribal warlord will steal the drugs and hoard them.
So the answer is no, it is not time for that to happen as the human race is no where near ready to start acting civilized.