EDIT - definitly worth a read and the aspect worth a quote "However, there still exists a version of the illness known as vaccine-derived polio, which occurs in rare incidents when the weakened virus in the vaccine mutates." Which is the instance at play here in the London sewage monitoring.
EDIT - definitly worth a read and the aspect worth a quote "However, there still exists a version of the illness known as vaccine-derived polio, which occurs in rare incidents when the weakened virus in the vaccine mutates." Which is the instance at play here in the London sewage monitoring.