RESUMO
Vaccines are considered the most economical and effective preventive measure against most deadly infectious diseases. Vaccines help protect around three million lives every year, but hundreds of thousands of lives are lost due to the instability of vaccines. This review discusses the various types of instability observed, while manufacturing, storing, and distributing vaccines. It describes the specific stability problems associated with each type of vaccine. This review also discusses the various measures adopted to overcome these instability problems. Vaccines are classified based on their components, and this review discusses how these preventive measures relate to each type of vaccine. This review also includes certain case studies that illustrate various approaches to improve vaccine stability. Last, this review provides insight on prospective methods for developing more stable vaccines.