Which vaccine in the Indian NIS schedule requires the STRICTEST cold chain maintenance, as it cannot be used if it has been frozen even once?

• A DPT ✓
• B OPV
• C BCG
• D IPV

Explanation

DPT and other adsorbed (adjuvanted) vaccines like Hepatitis B, TT, and DT are highly freeze-sensitive — freezing causes irreversible aggregation of the aluminium adjuvant, rendering the vaccine ineffective and potentially increasing local reactogenicity. The Shake Test is used to detect freezing in these vaccines. OPV, BCG, and MR can withstand freezing and in fact benefit from storage at freezing temperatures for extended periods. IPV, though temperature-sensitive, is also freeze-sensitive but DPT remains the classic example tested in examinations.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

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