Which statement is true about polio vaccines in terms of shedding and cold chain?

• A. OPV can shed in stool; IPV is inactivated and requires cold chain
• B. OPV requires refrigeration, IPV does not
• C. Both vaccines shed equally in stool
• D. Vaccines do not require cold chain

Answer: (A)

The key idea is how the two polio vaccines behave differently because of whether they contain live virus and how temperature affects them. The oral polio vaccine uses a live attenuated virus that can replicate in the gut, so it can be shed in stool after vaccination. The inactivated polio vaccine contains killed virus, so it cannot replicate or shed.

Cold chain matters for both: vaccines must be kept cold to preserve potency. Saying that IPV does not require cold chain is incorrect, and OPV also needs refrigeration to stay effective.

So the statement that best fits is: the oral vaccine can shed in stool, and the inactivated vaccine is inactivated and requires cold chain.