Poliovirus - Types vs. Strains
Dr. Bruno’s Original Post:
You often hear doctors on television news make a simple mistake: confusing the “types” of virus with “strains” of virus.
It's really simple. Each TYPE of virus requires its own specific antibody to subdue it. But within each TYPE of virus there can be many STRAINS that are genetically different (because of mutations) but still succumb to an attack by its TYPE’s antibody.
Dr. David Bodian discovered that there were 3 TYPES of poliovirus. A committee of scientists was formed and collected samples of poliovirus from North America and around the world to be certain that there were only 3 TYPES and therefore only 3 individual formulations of polio vaccines would be needed.
The findings confirming that there were just 3 TYPES of poliovirus were presented in 1952 at the Second International Poliomyelitis Conference. But also presented was the finding that there were:
255 STRAINS of TYPE 1 poliovirus,
36 STRAINS of TYPE 2 and
9 STRAINS of TYPE 3.
TYPE 1 STRAINS were by far the most numerous and virulent; so it's not surprising that they were responsible for the majority of polio epidemics.