Which outcome directly reflects interruption of transmission?

• A. Non-polio AFP rates
• B. Vaccination coverage
• C. Interruption of wild-type poliovirus transmission
• D. Adequacy of stool specimens

Answer: (C)

The main idea here is that the direct sign of success in polio eradication is that the wild poliovirus is no longer circulating in the population. When surveillance shows no wild-type poliovirus detected over a defined period and no linked paralysis cases, transmission has been interrupted. That is the actual end-state we aim for—the virus isn’t spreading anymore.

Non-polio AFP rates, while important for checking the sensitivity of surveillance (how good we are at spotting paralysis cases), do not confirm whether the virus is still transmitting. They reflect surveillance performance, not the current transmission status. Vaccination coverage tells us how many people are protected and how much herd immunity exists, which influences the risk of spread but doesn’t by itself prove that transmission has stopped. Adequacy of stool specimens measures the quality of specimen collection and testing—again a process-quality indicator, not a direct measure of whether the virus is circulating.