Social & Preventive Medicine Reverse cold chain is used for A Carrying stool samples of polio patients from a PHC to the lab B Transpoing outdated vaccines from PHC to district hospital C Transpoing vaccine to lab, to check its potency D Transpoing vaccine from camps to sub - centre 💡 Explanation Reverse cold chain is used for ✓ Correct Answer: A. Carrying stool samples of polio patients from a PHC to the lab