News / Health

Study Reveals Chink in Polio Vaccine’s Armor

A boy suffering from polio crawls beside his braces in Kinshasa, capital of the Democratic Republic of the Congo, November 29, 2011.
A boy suffering from polio crawls beside his braces in Kinshasa, capital of the Democratic Republic of the Congo, November 29, 2011.

A mutated polio virus that slipped through vaccine defenses caused an unusually lethal outbreak in the Republic of Congo in 2010, according to a new study. 

An intensive vaccination campaign was able to stop the virus. 

But the authors say their research shows new and dangerous strains may emerge as polio eradication nears, and high rates of vaccination are the best available protection.

Weaker vaccine

Polio usually paralyzes its victims. It is not typically fatal. But in the Republic of Congo outbreak, nearly half of the 445 people who got sick with the virus died. 

Health workers were especially concerned because about half of the patients remembered having been vaccinated. 

“That made it even more bizarre, because if they had been vaccinated, they shouldn’t be sick,” said virologist Felix Drexler at the University of Bonn.

When Drexler and colleagues in Europe and Africa studied the virus, they found it had some never-before-seen mutations in a critical part of its outer coat. Those mutations were in the place where antibodies that fight the virus would normally attach.

“We thought, ‘Wow, maybe that could affect the ability of the antibodies in human blood to neutralize the virus,’” Drexler said. 

It did. When they tested the virus in Germany against blood samples from people with better-than-average vaccination coverage, they found that 15 to 29 percent of them would not be protected from the mutant strain.

The research is published in the Proceedings of the National Academy of Sciences.

Virus stopped

The Republic of Congo had been polio free before the outbreak. It took four nationwide immunization drives targeting every man, woman and child to stop the mutated virus. 

Drexler said the effort worked because just about everyone got vaccinated with the most potent form of the vaccine. 

The virus has not been seen since, though Drexler said it’s possible it’s still lurking out there somewhere. And, he added, there may be others that also can evade the vaccine's protection. 

Experts say polio eradication is in its final stages. There have been fewer than 150 cases anywhere in the world this year, and the virus is found regularly in just three countries. 

Good enough?

But, Drexler noted, “The question that the experts are asking is, 'Is the vaccine good enough to enable us to eradicate poliovirus?'”

Virologist Olen Kew with the U.S. Centers for Disease Control and Prevention says it is. He was not involved with this study. He noted that the vaccine has eliminated the virus everywhere it has been used.

“What happened in Congo was, it hadn’t been used for quite a long period of time and a susceptible group opened up,” he said. Civil unrest disrupted vaccination campaigns in the 1990s and early 2000s. “And when the virus was introduced, it had devastating effects.”

Kew said the reason the virus was so deadly was because the susceptible group was young adults, not the children who are usually affected. 

“It’s been known for a long time that older age groups, once they get infected, can have more severe disease than younger children,” he said.

Associate Director Walt Orenstein at the Emory Vaccine Center, who was also not involved in the study, said more potent vaccines would be helpful to protect against mutated viruses.

However, he added, “I think the most important message, to me, is, we need to push hard and push fast and terminate transmission as quickly as possible, in which case this becomes irrelevant.”

You May Like

Ukraine Purges Interior Ministry Leadership With Pro-Russian Ties

Interior Minister Avakov says 91 people 'in positions of leadership' have been fired, including 8 generals found to have links to past pro-Moscow governments More

US Airlines Point to Additional Problems of any Ebola Travel Ban

Airline officials note that even under travel ban, they may not be able to determine where passenger set out from, as there are no direct flights from Liberia, Guinea or Sierra Leone More

Nigerian President to Seek Another Term

Goodluck Jonathan has faced intense criticism for failing to stop Boko Haram militants More

This forum has been closed.
Comment Sorting
Comments
     
by: eusebio from: Portugal
August 20, 2014 12:42 PM
Stop Pólio in DRCongo sustainable solutions in the areas of the fight against Pólio

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
Talks to Resume on Winter Gas for Ukrainei
X
Al Pessin
October 25, 2014 4:21 PM
Ukrainian and Russian officials will meet again next week in an effort to settle their dispute over natural gas supplies that threatens to leave Ukraine short of heating fuel for the coming winter. VOA’s Al Pessin reports from London the dispute is complex, and has both economic and geopolitical dimensions.
Video

Video Talks to Resume on Winter Gas for Ukraine

Ukrainian and Russian officials will meet again next week in an effort to settle their dispute over natural gas supplies that threatens to leave Ukraine short of heating fuel for the coming winter. VOA’s Al Pessin reports from London the dispute is complex, and has both economic and geopolitical dimensions.
Video

Video Smugglers Offer Cheap Passage From Turkey to Syria

Smugglers in Turkey offer a relatively cheap passage across the border into Syria. Ankara has stepped up efforts to stem the flow of foreign fighters who want to join Islamic State militants fighting for control of the Syrian border city of Kobani. But porous borders and border guards who can be bribed make illegal border crossings quite easy. Zlatica Hoke has more.
Video

Video China Political Meeting Seeks to Improve Rule of Law

China’s communist leaders will host a top level political meeting this week, called the Fourth Plenum, and for the first time in the party’s history, rule of law will be a key item on the agenda. Analysts and Chinese media reports say the meetings could see the approval of long-awaited measures aimed at giving courts more independence and include steps to enhance an already aggressive and high-reaching anti-corruption drive. VOA’s Bill Ide has more from Beijing.
Video

Video After Decades of Pressure, Luxembourg Drops Bank Secrecy Rules

European Union finance ministers have reached a breakthrough agreement that will make it more difficult for tax cheats to hide their money. The new legislation, which had been blocked for years by countries with a reputation as tax havens, was approved last week after Luxembourg and Austria agreed to lift their vetoes. But as Mil Arcega reports, it doesn’t mean tax cheats have run out of places to keep their money hidden.
Video

Video Kobani Refugees Welcome, Turkey Criticizes, US Airdrop

Residents of Kobani in northern Syria have welcomed the airdrop of weapons, ammunition and medicine to Kurdish militia who are resisting the seizure of their city by Islamic State militants. The Turkish government, however, has criticized the operation. VOA’s Scott Bobb reports from southeastern Turkey, across the border from Kobani.
Video

Video US ‘Death Cafes’ Put Focus on the Finale

In contemporary America, death usually is a topic to be avoided. But the growing “death café” movement encourages people to discuss their fears and desires about their final moments. VOA’s Jerome Socolovsky reports.
Video

Video Ebola Orphanage Opens in Sierra Leone

Sierra Leone's first Ebola orphanage has opened in the Kailahun district. Hundreds of children orphaned since the beginning of the Ebola outbreak face stigma and rejection with nobody to care for them. Adam Bailes reports for VOA about a new interim care center that's aimed at helping the growing number of children affected by Ebola.

All About America

AppleAndroid