Why is maintaining cold chain important for polio vaccines?

• A. It is unnecessary with modern vaccines
• B. It only matters for storage in laboratories
• C. It ensures vaccine potency; OPV is heat-labile and IPV requires refrigeration
• D. It ensures only packaging integrity

Answer: (C)

Keeping vaccines cold from manufacture to administration is essential because polio vaccines are temperature-sensitive and must stay potent to work. The oral polio vaccine is a live attenuated vaccine that loses activity if exposed to heat, which can reduce its ability to replicate in the gut and elicit a protective immune response. The inactivated polio vaccine is made of killed viral proteins that can be denatured by heat, also diminishing the immune response if they aren’t kept cold. If the cold chain is broken, potency drops and immunity may be incomplete, wasting resources and risking under-protected populations. Proper refrigeration (and protection from freezing and overheating) throughout storage and transport keeps both vaccines effective at the time of use.