Polio nearly gone; should vaccine end too?

As the virus is confined to fewer countries, public health officials consider when and if to cease vaccinations.

By Victoria Stagg Elliott, AMNews staff. Jan. 14, 2002.

Polio is now endemic to only 11 countries and fewer than 500 cases were reported globally in 2001, according to data released by the Centers for Disease Control and Prevention.

But, despite the fact that the last U.S. case of transmission of wild-type polio was in 1979, experts say vaccinations against the disease will still be necessary for years to come.

This caution is due in part to incidents of importation of the disease to the United States from other areas, but also because of transmission connected to live vaccine. Experts also worry about unvaccinated pockets that could become disease reservoirs.

"The big question now is when will we be able to stop using the vaccine," said Arnold Monto, MD, an infectious diseases epidemiologist at the University of Michigan, Ann Arbor. "I think we're going to be conservative about this. Ten years may not be enough."

Of the 152 cases recorded domestically by the CDC from 1980 to 1999, 95% were vaccine-related. There have also been significant outbreaks in the Dominican Republic and Haiti because the virus used in the vaccine mutated and spread -- causing infection among those not vaccinated.

"This adds a complexity to eradicating the polio virus," said Stephen Cochi, MD, MPH, head of the CDC's Global Immunization Division. Dr. Cochi presented the latest data about the status of global polio eradication efforts at the Interscience Conference on Antimicrobial Agents and Chemotherapy in Chicago last month.

"The vaccine virus acted like an actual polio virus and caused an outbreak. This was a warning, and over the long-term, we need to stop using the oral vaccine," he said. [...]