World Two Strains of Polio Are Gone, but the End of the Disease Is Still Far Off October 23, 2019October 23, 2019DONALD G. McNEIL Jr.Comments Off on Two Strains of Polio Are Gone, but the End of the Disease Is Still Far Off Only polio virus Type 1 persists, and only in Pakistan and Afghanistan. But now mutant vaccine viruses are paralyzing some unvaccinated children.
