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

Tunnel Bombs Highlight Savagery of Aleppo Fight

Rebels have used tunneling tactic near government buildings, command posts or supply routes to set off explosives; they detonated their largest bomb this week under Syria's intelligence headquarters More

Sierra Leone Launches New Initiative to Stop Ebola Spread

Government hopes Infection and Prevention Control Units, IPC, will help protect patients and healthcare workers More

UN Official: Fight Against Terrorism Must Not Violate Human Rights

UN High Commissioner for Human Rights says efforts by states to combat terrorism are resulting in large scale rights violations against the very citizens they claim to defend 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.
Video Claims to Show Shia Forces in Iraq Executing Sunni Boyi
X
Jeff Seldin
March 05, 2015 2:36 AM
A graphic mobile phone video is spreading on the Internet, claiming to show Iraqi forces or Shia militia executing a handcuffed Sunni boy. Experts have yet to verify the video, but already Islamic State followers are publicizing it across social media, playing on deep-rooted sectarian fears. VOA’s Jeff Seldin reports.
Video

Video Video Claims to Show Shia Forces in Iraq Executing Sunni Boy

A graphic mobile phone video is spreading on the Internet, claiming to show Iraqi forces or Shia militia executing a handcuffed Sunni boy. Experts have yet to verify the video, but already Islamic State followers are publicizing it across social media, playing on deep-rooted sectarian fears. VOA’s Jeff Seldin reports.
Video

Video Ukrainian Authorities Struggle to Secure a Divided Mariupol

Since last month's cease-fire went into effect, shelling around the port city of Mariupol has decreased, but it is thought pro-Russian separatists remain poised to attack. For the city’s authorities, a major challenge is gaining the trust of residents, while at the same time rooting out informants who are passing sensitive information to the rebels. Patrick Wells reports for VOA.
Video

Video Volunteer Gauge-Watchers Help Fine-Tune Weather Science

An observation system called CoCoRaHS is working to improve weather science, thanks to thousands of volunteers across the country who measure precipitation in their own backyards, then share their data through the Internet. VOA's Shelley Schlender reports.
Video

Video NASA Spacecraft Approaches a Dwarf Planet

NASA’s Dawn spacecraft will make history on Friday, March 6, when it becomes the first man-made object to orbit a dwarf planet named Ceres. It is located in the asteroid belt between Mars and Jupiter, almost 500 million kilometers from Earth. Among other objectives, Dawn will try to examine two mysterious bright white spots detected on the planet’s surface. VOA’s George Putic has more.
Video

Video Young Muslims Radicalized Online

Young Muslims are being radicalized ‘in their bedrooms’ through direct contact with Islamic State or ISIL fighters via the Internet, according to terror experts. There are growing concerns that authorities and Internet providers are not doing enough to counter online extremism - which analysts say is spread by a prolific network of online supporters around the world. Henry Ridgwell reports from London.
Video

Video African Americans Recall 1960s Fight For Voting Rights

U.S. President Barack Obama and thousands of people will gather in the small southern U.S. city of Selma, Alabama, Saturday, March 7 to commemorate the 50th anniversary of a historic voting rights march that became known as “Bloody Sunday." VOA’s Chris Simkins traveled to Alabama and introduces us to some of the foot soldiers of the voting rights struggles of the 1960s.
Video

Video Positive Messaging Transforms Ethiopia's Image

Ethiopia was once known for famine and droughts. Now, headlines more often point to its fast-growing economy and its emergence as a regional peacemaker. How has Addis Ababa changed the narrative? VOA's Marthe van der Wolf reports.
Video

Video Cyber War Rages Between Iran, US

A newly published report indicates Iran and the United States have increased their cyber attacks on each other, even as their top diplomats are working toward an agreement to guarantee Iran does not develop a nuclear weapon and to free Iran from international sanctions. The development is part of a growing global trend. VOA’s Al Pessin reports from London.
Video

Video Answers Elude Families of MH370 Passengers

For the families on board Malaysia Airlines flight MH370, an airline official’s statement nearly one year ago that the plane had lost contact with air traffic control at 2:40 AM is the only thing that remains confirmed. William Ide reports.

All About America

Circumventing Censorship

An Internet Primer for Healthy Web Habits

As surveillance and censoring technologies advance, so, too, do new tools for your computer or mobile device that help protect your privacy and break through Internet censorship.
More