Vaccine Development, Successes and Failures

In the 200 years since vaccination was introduced, smallpox remains the only disease that we have successfully eradicated with vaccines. We have in our hands, vaccines for pneumonia, polio and measles, but why have we not eradicated these diseases? And do vaccines always provide complete and lifelong immunity? We discuss how vaccines are developed and their successes and failures with Dr Peter Paradiso, vaccine consultant.