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

On Everest, Helicopters Rescue Stranded Climbers

Choppers transport some of more than 100 mountaineers trapped after deadly quake, avalanches More

Video Ten Years After Riots, France Searches for Answers to Neglected Suburbs

In 2005, a Paris suburb exploded into violence after two teenagers were electrocuted as they hid from police; since then, somethings have changed, others not More

US, Japan Announce Historic Revision of Defense Cooperation Guidelines

Nations say new guidelines will be 'cornerstone for peace and security' in Asia-Pacific region while also serving as 'platform for a more stable international security environment' 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.
‘Angel of the Migrants’ Helps Desperate Syrians Arriving in Europei
X
Henry Ridgwell
April 26, 2015 10:36 PM
Waves of migrants are continuing to arrive on the shores of southern Italy from North Africa. After their dangerous journey across the Mediterranean, they face an unknown future in Europe. In the Sicilian city of Catania there is an activist dedicated to helping the refugees on their journey.
Video

Video ‘Angel of the Migrants’ Helps Desperate Syrians Arriving in Europe

Waves of migrants are continuing to arrive on the shores of southern Italy from North Africa. After their dangerous journey across the Mediterranean, they face an unknown future in Europe. In the Sicilian city of Catania there is an activist dedicated to helping the refugees on their journey.
Video

Video Ten Years After Riots, France Searches for Answers to Neglected Suburbs

January’s terrorist attacks and fears of more to come are casting a spotlight on France’s neglected suburbs. Home to many immigrants, and sometimes hubs of crime, they were rocked by rioting a decade ago. Lisa Bryant visited the Paris suburb of Clichy-sous-Bois, where the 2005 violence first broke out, and has this report about what has changed and what has not.
Video

Video Gay Marriage Goes Before US Supreme Court

This week, the U.S. Supreme Court will hear arguments on whether gay people have a constitutional right to marriage. VOA’s Michael Bowman reports, the case could lead to the nationwide legalization of same-sex marriage, or a continuation of the status quo in which individual states decide whether to recognize gay unions.
Video

Video Study: Insecticide Damaging Wild Bee Populations

A popular but controversial type of insecticide is damaging important wild bee populations, according to a new study. VOA’s Steve Baragona has more.
Video

Video Data Servers Could Heat Private Homes

As every computer owner knows, when their machines run a complex program they get pretty hot. In fact, cooling the processors can be expensive, especially when you're dealing with huge banks of computer servers. But what if that energy could heat private homes? VOA’s George Putic reports that a Dutch energy firm aims to do just that.
Video

Video Cinema That Crosses Borders Showcased at Tribeca Film Festival

Among the nearly 100 feature length films being shown at this year’s Tribeca Film Festival in New York City are more than 20 documentaries and features with international appeal, from a film about a Congolese businessman in China, to documentaries shot in Pakistan and diaspora communities in the U.S., to a poetic look at disaffected South African youth. VOA’s Carolyn Weaver has more.
Video

Video UN Confronts Threat of Young Radicals

The radicalization and recruitment of young people into Islamist extremist groups has become a growing challenge for governments worldwide. On Thursday, the U.N. Security Council heard from experts on the issue, which has become a potent threat to international peace and security. VOA’s Margaret Besheer reports.
Video

Video Growing Numbers of Turks Discover Armenian Ancestry

In a climate of improved tolerance, growing numbers of people in Turkey are discovering their grandmothers were Armenian. Hundreds of thousands of Armenians escaped the mass deportations and slaughter of the early 1900's by forced conversion to Islam. Or, Armenian children were taken in by Turkish families and assimilated. Now their stories are increasingly being heard. Dorian Jones reports from Istanbul that the revelations are viewed as an important step.
Video

Video Migrants Trek Through Western Balkans to Reach EU

Migrants from Africa and other places are finding different routes into the European Union in search of a better life. The Associated Press followed one clandestine group to document their trek through the western Balkans to Hungary. Zlatica Hoke reports that the migrants started using that route about four years ago. Since then, it has become the second-most popular path into Western Europe, after the option of sailing from North Africa to Italy.
Video

Video US Businesses See Cuba as New Frontier

The Obama administration's opening toward Cuba is giving U.S. companies hope they'll be able to do business in Cuba despite the continuation of the U.S. economic embargo against the communist nation. Some American companies have been able to export some products to Cuba, but the recent lifting of Cuba's terrorism designation could relax other restrictions. As VOA's Daniela Schrier reports, corporate heavy hitters are lining up to head across the Florida Straits - though experts urge caution.
Video

Video Kenya Launches Police Recruitment Drive After Terror Attacks

Kenya launched a major police recruitment drive this week as part of a large-scale effort to boost security following a recent spate of terror attacks. VOA’s Gabe Joselow reports that allegations of corruption in the process are raising old concerns about the integrity of Kenya’s security forces.
Video

Video Japan, China in Race for Asia High-Speed Rail Projects

A lucrative competition is underway in Asia for billions of dollars in high-speed rail projects. Cambodia, India, Indonesia, Malaysia Thailand and Vietnam are among the countries planning to move onto the fast track. They are negotiating with Japan and the upstart Chinese who are locked in a duel to revolutionize transportation across Asia. VOA Correspondent Steve Herman in Bangkok has details.
Video

Video Scientists: Mosquitoes Attracted By Our Genes

Some people always seem to get bitten by mosquitoes more than others. Now, scientists have proved that is really the case - and they say it’s all because of genes. It’s hoped the research might lead to new preventative treatments for diseases like malaria, as Henry Ridgwell reports from London.
Video

Video Bible Museum Coming to Washington DC

Washington is the center of American political power and also home to some of the nation’s most visited museums. A new one that will showcase the Bible has skeptics questioning the motives of its conservative Christian funders. VOA religion correspondent Jerome Socolovsky reports.
Video

Video Afghan First Lady Pledges No Roll Back on Women's Rights

Afghan First Lady Rula Ghani, named one of Time's 100 Most Influential, says women should take part in talks with Taliban. VOA's Rokhsar Azamee has more from Kabul.

VOA Blogs