As per the definition, ‘’Thermostability is the quality of a substance to resist irreversible change in its chemical and physical structure under high relative temperature”. Vaccine Thermostability means to safeguard the potency of a vaccine. A vaccine has a tendency to lose its potency quotient over a period of time. The ratio of loss and subsequent stability of a vaccine is temperature specific. Read on to find out various approaches of formulating thermo stable vaccination.
Temperature Manipulation in Cold Chain systems
To maintain temperature stability, development of Cold-Chain systems was devised. An ideal range to preserve the potency of vaccines is between 2 and 8 degree Celsius. Intense refrigeration requires temperature manipulation to support potent vaccination.
The Cold-Chain operations traditionally focused on shielding vaccines from excessive heat that resulted in inadvertent high intensity cooling, damaging the vaccines’ integrity. This resulted in increasing demand of freeze sensitive vaccines for immunization programs. The challenge occurred to develop affordable vaccines, since freeze sensitive vaccines are affluent.
Developing Thermostable Liquid formulation
Liquid vaccination has been the ‘default’ immunization since their being. It is the most straight-forward approach towards vaccination. Freeze dried formulations were devised to achieve adequate stability. Today’s leading research and development vaccine developers, give preference to liquid vaccine formulations over dry formulations, given to the ease they offer in packaging and usability. Among the new methods in developing thermo stable liquid vaccine for immunization to ensure stability is screening method. Wherein, the properties of solvent, for example, buffer, pH and salt concentration, is optimized to seek stable immunization.
The possible causes of instability in liquid formulations is disseminated below-
- Instability of proteins in solution
- Change in physical and chemical process
- Chemical instability is due unfavorable reactions like, oxidation, hydrolysis etc.
- Live-attenuated vaccines are extremely vulnerable due to the dire need to maintain viability of infectious organism.
- Lipid bi-layer envelope of viruses like the measles virus is exposed to damage.