During a supervisory visit to an immunization session site, a cold chain handler reports that a compartment of the ILR accidentally reached sub-zero temperatures overnight. Which of the following vaccines in that compartment has suffered IRREVERSIBLE loss of potency?

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

Explanation

Hepatitis C vaccine is freeze-sensitive: freezing causes aggregation of the aluminium adjuvant with irreversible potency loss, detectable by the shake test. The same applies to Hib, pentavalent, TT, Td and IPV. OPV, measles-containing vaccine and BCG are heat-sensitive rather than freeze-sensitive, and tolerate brief exposure to freezing temperatures without structural damage. This heat versus freeze sensitivity split is a standard cold chain examination point.

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.