During a supervision visit, a medical officer finds that a cold box containing vaccines was accidentally stored against the freezer wall overnight. According to cold chain rules, which of these vaccines is MOST vulnerable to damage by freezing?

• A Hepatitis B vaccine ✓
• B Measles-containing vaccine
• C Oral poliovirus vaccine
• D BCG vaccine

Explanation

Freezing destroys adjuvanted (aluminium-salt adsorbed) vaccines such as hepatitis B, pentavalent (HepB and Hib components), DTP and Td, causing irreversible potency loss and increased reactogenicity; the shake test detects such damage. OPV, BCG and measles vaccines, by contrast, are chiefly heat sensitive and tolerate freezing far better. Hence hepatitis B must never touch frozen ice packs directly.

Reference: Park's Textbook of Preventive and Social Medicine, 27th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.