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

Karzai's Legacy: Missed Opportunities?

Afghanistan's president leaves behind a much different nation than the one he inherited, yet his legacy from 13 years in power is getting mixed reviews More

Video Secret Service Chief Under Fire for White House Security Breach

Julia Pierson faces tough questions from lawmakers after recent intrusion at White House, says: 'It is clear that our security plan was not executed properly' More

Frustrated, Liberian Students Want Ebola Fight Role

Thousands have volunteered to go to counties, rural villages to talk to people in their language about deadly virus 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.
Malaysia Struggles to Stop People Joining Jihadi
X
Mahi Ramakrishnan
September 30, 2014 2:16 PM
Malaysian authorities say militant groups like the so-called "Islamic State" have used social media to entice at least three dozen Malaysian Muslims to fight in what they call "jihad" in Syria and Iraq. As Mahi Ramkrishnan reports from Kuala Lumpur, counterterrorism police are deeply worried about what could happen when these militants return home.
Video

Video Malaysia Struggles to Stop People Joining Jihad

Malaysian authorities say militant groups like the so-called "Islamic State" have used social media to entice at least three dozen Malaysian Muslims to fight in what they call "jihad" in Syria and Iraq. As Mahi Ramkrishnan reports from Kuala Lumpur, counterterrorism police are deeply worried about what could happen when these militants return home.
Video

Video Could US Have Done More to Stop Rise of Islamic State?

President Obama says airstrikes against Islamic State militants in Syria will likely continue for some time because, in his words, "there is a cancer that has grown for too long." So what if President Obama had acted sooner in Syria to arm more-moderate opponents of both the Islamic State and the Syrian government? VOA State Department Correspondent Scott Stearns reports from the United Nations.
Video

Video Treasure Hunters Seek 'Hidden Treasure' in Central Kenya

Could a cave in a small village in central Kenya be the site of buried treasure? A rumor of riches, left behind by colonialists, has some residents dreaming of wealth, while others see it as a dangerous hoax. VOA's Gabe Joselow has the story.
Video

Video Iran's Rouhani Skeptical on Syria Strikes

Iranian President Hassan Rouhani expressed skepticism Friday that U.S.-led airstrikes in Iraq and Syria could crush Islamic State militants. From New York, VOA’s Margaret Besheer reports the president was also hopeful that questions about Iran’s nuclear program could be resolved soon.
Video

Video US House Speaker: Congress Should Debate Authorization Against IS

As wave after wave of U.S. airstrikes target Islamic State militants, the speaker of the Republican-controlled House of Representatives says he would be willing to call Congress back into session to debate a formal, broad authorization for the use of military force. VOA’s Michael Bowman reports from Washington, where legislators left town 10 days ago for a seven-week recess.
Video

Video Ebola Patients Find No Treatment at Sierra Leone Holding Center

At a holding facility in Makeni, central Sierra Leone, dozens of sick people sit on the floor in an empty university building. They wait in filthy conditions. It's a 16-hour drive by ambulance to Kailahun Ebola treatment center. Adam Bailes was there and reports on what he says are some of the worst situations he has seen since the beginning of this Ebola outbreak. And he says it appears case numbers may already be far worse than authorities acknowledge.
Video

Video Identifying Bodies Found in Texas Border Region

Thousands of immigrants have died after crossing the border from Mexico into remote areas of the southwestern United States in recent years. Local officials in south Texas alone have found hundreds of unidentified bodies and buried them in mass graves in local cemeteries. Now an anthropologist and her students at Baylor University have been exhuming bodies and looking for clues to identify them. VOA’s Greg Flakus has more from Waco, Texas.
Video

Video Ebola Robs Liberians of Chance to Say Good-Bye to Loved Ones

In Liberia, where Ebola has killed more than 1,500 people, authorities have worked hard to convince people to allow specialized burial teams to take away dead bodies. But these safety measures, while necessary, make it hard for people to say good bye to their loved ones. VOA's Anne Look reports on the tragedy from Liberia.
Colonel Steve ‘Spiros’ Pisanos left Greece and came to the U.S. to learn to fly. He flew fighters for the Allies in World War II, narrowly escaping death multiple times.Colonel Steve ‘Spiros’ Pisanos left Greece and came to the U.S. to learn to fly. He flew fighters for the Allies in World War II, narrowly escaping death multiple times.

AppleAndroid