Although it's pretty evident that vaccinations serve numerous benefits to societies' collective health, I think that there are several notable limitations to address. First of all, financing for immunization practices remains a significant challenge. According to the 2007 study done by the World Health Organization, a severe funding gap of approximately 13 billion USD is expected to remain if around 10 million more lives are to be saved through this practice. Second of all, concerns regarding the financial sustainability of future vaccination efforts in developing countries remain, as financial responsibility between national organizations will be necessary. Finally, a study titled "The complexity and cost of vaccine manufacturing—An overview" shows that for lower and middle income countries to acquire adequate immunization practices, a significant amount of medical equipment, personnel, and consumables will need to be imported for numerous years. All of this goes to show the economic challenges that persist within the spread of vaccination programs and initiatives.