I didn't mean to imply that drug companies have an obligation to produce products that aren't commercially viable. I understand that's just not the way the world works at the moment. I was just curious whether anyone knew whether lack of commercial viability was the reason we haven't seen a malaria vaccine yet.

Thirty years to reach this point isn't necessarily representative of the actual effort expended on finding a malaria vaccine. I wouldn't be surprised to discover that the same number of working hours goes towards treatments for male pattern baldness each year as has gone into a malaria vaccine over thirty years.