Under the Universal Immunisation Programme (UIP) in India, several vaccines are stored at +2°C to +8°C in the cold chain. Which of the following vaccines is freeze-sensitive and must NEVER be frozen?

• A Tetanus toxoid (TT) ✓
• B BCG vaccine
• C Oral polio vaccine (OPV)
• D Measles vaccine (lyophilized)

Explanation

Tetanus toxoid and other aluminium-adjuvanted vaccines (DPT, Td, hepatitis B, Hib) are freeze-sensitive. Freezing causes the aluminium adjuvant to flocculate and precipitate, destroying the depot effect and reducing immunogenicity. OPV is stored frozen at -20°A. BCG and lyophilized measles vaccine are freeze-dried and are heat-sensitive rather than freeze-sensitive; once reconstituted, they must be kept at +2 to +8°A and used within a few hours.

Reference: WHO Immunization in Practice Module 2: The Immunization Cold Chain, Updated 2015 ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.