Karen Torgaly

Sabin had decided that he wanted to make a live virus vaccine.

The difference between the two was that the live virus vaccine was weak, but it was still alive.

And the way he did that was the strains that were infectious to humans, he would take samples of those and inject monkeys and let the monkeys get sick.

They would take samples from that monkey and inject it into another monkey.

They would get sick.

And he kept doing it until the vaccine didn't cause disease anymore.

But it was still the same strain.

It had just mutated enough that it didn't cause disease.

But what can happen with a live virus vaccine is that it can revert to virulence.

If it's put into a body that doesn't have a strong immune system, for instance, that body can develop their disease.

And that was the big concern.

But it was so rare that they didn't even realize that it could happen until years later.

So they had this fundamental difference in the kind of vaccine that they wanted to make, and they had lots of arguments about why one was better than the other.

Sabin very firmly believed that a live virus vaccine would produce a longer kind of immunity and a lifelong immunity, whereas the Salk vaccine, the killed virus vaccine, would have to be repeated every few years.

People in the initial dose would have to get one shot for each of the three strains of virus that caused disease and then a booster.

So there's starting to be this division in the polio vaccine community.

And that was kind of when Sabin and Salk started to part their ways, too.

He would say no.

He just said, you know, a lot of that was blown up by the press because it sold newspapers.

He said, no, he said we had a fine relationship, but other people who were witnesses to some of their interactions would not have agreed with them.