Dear Colleagues:
I'm a bacteriologist, not a virologist, so please excuse my ignorance. I
thought that polio vaccination hasn't eliminated polio. There is still
virulent polio about but that it has largely been "crowded out" by the vaccine
strain. The vaccine strain is being shed and is in our water and sewage. There
may also be a "herd effect" in that vaccinates may indirectly immunize
non-vaccinates by contamination and by breaking the cycle of the virulent
strains. Comments?....John