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This one-two punch could help eradicate polio

Shots, drops – which to use has been controversial
Polio has been wiped out of many countries because of massive use of oral vaccine. But new research suggests trying a one-two punch, where the disease is still a threat: Giving a single vaccine shot to children who’ve already gotten the drops boosted their immunity.

WASHINGTON – New research suggests a one-two punch could help battle polio in some of the world’s most remote and strife-torn regions: Giving a single vaccine shot to children who’ve already swallowed drops of an oral polio vaccine greatly boosted their immunity.

The World Health Organization officials said the combination strategy already is starting to be used in mass vaccination campaigns in some hard-hit areas and is being introduced for routine immunizations in developing countries, too.

“It could play a major role in completing the job of polio eradication once and for all,” said Dr. Hamid Jafari, WHO’s director of polio operations, who led the study published in the journal Science.

Oral polio vaccine has played a critical role in the nearly three-decade effort to eradicate the paralyzing disease, as health workers have gone house-to-house, to refugee camps and to roadside checkpoints delivering the drops. The number of countries where polio regularly circulates dropped from 125 in 1988 to just three as of last year – Pakistan, Nigeria and Afghanistan.

But with travel, the threat is re-emerging in countries previously free of the highly contagious virus. The WHO in May declared an international public-health emergency, citing outbreaks in at least 10 countries. Particularly of concern were Syria, Somalia and Iraq, where violence has complicated efforts to contain new cases.

Which vaccine to use in the eradication push has long been controversial. They each have different strengths. The United States and other wealthy countries have switched back to using only injected polio vaccine, which is made of “inactivated” or killed virus, for routine childhood immunizations after eradicating the disease within their borders. That’s because the oral vaccine contains weakened live virus that children can shed in their stools, which on very rare occasions can trigger a vaccine-caused case of polio.

The injected vaccine is more expensive, Aylward said – about $1 to $1.90 a shot under specially negotiated prices for low-income countries, compared with about 15 cents a dose for oral vaccine. But he said it was worth the investment if adding the shots wound up eliminating polio in the last infected areas faster.

Using this strategy in these tough-to-reach areas makes sense, said CDC vaccine expert Dr. Steve Cochi.

“We want to take maximum advantage of each contact with a child,” he said. “It’s the start of the last stand for wild polio virus, and we’re trying to hit it with both vaccines.”

At the same time, the WHO has called on low- and middle-income countries that now use only oral polio vaccine to add one dose of the injected version to routine childhood immunizations next year.



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