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

Video Russia Accused of Abusing Interpol to Pursue Opponents

Report from member of British think tank says Russian extradition requests keep targets from traveling More

US Lawmakers Weigh Turkish Anti-terror Moves

Turkey’s two-pronged campaign against Islamic State militants, Kurdish PKK forces provokes mixed reactions on Capitol Hill More

What Happens When Americans Eat What They Tweet

You are what you tweet, according to new maps that show a correlation between obesity and tweeting about high-fat foods 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.
Russia Accused of Abusing Interpol to Pursue Opponentsi
X
Henry Ridgwell
July 28, 2015 9:53 PM
A British pro-democracy group has accused Russia of abusing the global law enforcement agency Interpol by requesting the arrest and extradition of political opponents. A new report by the group notes such requests can mean the accused are unable to travel and are often unable to open bank accounts. VOA's Henry Ridgwell reports.
Video

Video Russia Accused of Abusing Interpol to Pursue Opponents

A British pro-democracy group has accused Russia of abusing the global law enforcement agency Interpol by requesting the arrest and extradition of political opponents. A new report by the group notes such requests can mean the accused are unable to travel and are often unable to open bank accounts. VOA's Henry Ridgwell reports.
Video

Video Genome Initiative Urgently Moves to Freeze DNA Before Species Go Extinct

Earth is in the midst of its sixth mass extinction. The last such event was caused by an asteroid 66 million years ago. It killed off the dinosaurs and practically everything else. So scientists are in a race against time to classify the estimated 11 million species alive today. So far only 2 million are described by science, and researchers are worried many will disappear before they even have a name. VOA’s Rosanne Skirble reports.
Video

Video Scientists: One-Dose Malaria Cure is Possible

Scientists have long been trying to develop an effective protection and cure for malaria - one of the deadliest diseases that affects people in tropical areas, especially children. As the World Health Organization announces plans to begin clinical trials of a promising new vaccine, scientists in South Africa report that they too are at an important threshold. George Putic reports, they are testing a compound that could be a single-dose cure for malaria.
Video

Video Special Olympics Athletes Meet International Friends

The Special Olympics are underway in Los Angeles, California, with athletes from 165 countries participating in an event that gives people with intellectual disabilities the chance to take part in an international competition. VOA's Mike O'Sullivan reports that for athletes and their families, it's also an opportunity to make new friends in an international setting.
Video

Video 'New York' Magazine Features 35 Cosby Accusers

The latest issue of 'New York' magazine features 35 women who say they were drugged and raped by film and television celebrity Bill Cosby. The women are aged from 44 to 80 and come from different walks of life and races. The magazine interviewed each of them separately, but Zlatica Hoke reports their stories are similar.
Video

Video US Calls Fight Against Human Trafficking a Must Win

The United States is promising not to give up its fight against what Secretary of State John Kerry calls the “scourge” of modern slavery. Officials released the country’s annual human trafficking report Monday – a report that’s being met with some criticism. VOA’s National Security correspondent Jeff Seldin has more from the State Department.
Video

Video Iran Nuclear Pact Wins Few New US Congressional Backers

Later this week, President Barack Obama returns from a trip to Africa to confront a U.S. Congress roiled by the nuclear accord with Iran, an agreement that has received the blessing of the U.N. Security Council. Days of intensive lobbying and testimony by top administration officials have won few new congressional supporters of the pact. VOA’s Michael Bowman reports.
Video

Video Washington DC Underground Streetcar Station to Become Arts Venue

Abandoned more than 50 years ago, the underground streetcar station in Washington D.C.’s historic DuPont Circle district is about to be reborn. The plan calls for turning the spacious underground platforms - once meant to be a transportation hub, - into a unique space for art exhibitions, presentations, concerts and even a film set. Roman Mamonov has more from beneath the streets of the U.S. capital. Joy Wagner narrates his report.
Video

Video Europe’s Twin Crises Collide in Greece as Migrant Numbers Soar

Greece has replaced Italy as the main gateway for migrants into Europe, with more than 100,000 arrivals in the first six months of 2015. Many want to move further into Europe and escape Greece’s economic crisis, but they face widespread dangers on the journey overland through the Balkans. VOA's Henry Ridgwell reports.
Video

Video Stink Intensifies as Lebanon’s Trash Crisis Continues

After the closure of a major rubbish dump a week ago, the streets of Beirut are filling up with trash. Having failed to draw up a plan B, politicians are struggling to deal with the problem. John Owens has more for VOA from Beirut.
Video

Video Paris Rolls Out Blueprint to Fight Climate Change

A U.N. climate conference in December aims to produce an ambitious agreement to fight heat-trapping greenhouse gases. But many local governments are not waiting, and have drafted their own climate action plans. That’s the case with Paris — which is getting special attention, since it’s hosting the climate summit. Lisa Bryant takes a look for VOA at the transformation of the French capital into an eco-city.
Video

Video Racially Diverse Spider-Man Takes Center Stage

Whether it’s in a comic book or on the big screen, fans have always known the man behind the Spider-Man mask as Peter Parker. But that is changing, at least in the comic book world. Marvel Comics announced that a character called Miles Morales will replace Peter Parker as Spider-Man in a new comic book series. He is half Latino, half African American, and he is quite popular among comic book fans. Correspondent Elizabeth Lee reports from Los Angeles.
Video

Video Critics of Japan Defense Policy Focus on Okinawa

In Okinawa, many locals have long complained that Tokyo places an unfair burden on the tiny island by locating most of Japan's U.S. military bases there. As Japan's government moves toward strengthening and expanding the country's defense policies, opponents of those plans are joining local protesters in Okinawa, voicing concern about where the country is headed. VOA’s Brian Padden reports from Okinawa.
Video

Video IS Uses Chemical Weapons in Syrian Attack

Islamic State militants have added a new weapon in their arsenal of fear: chemical weapons. VOA Kurdish service reporter Zana Omer was on the scene within hours of a recent attack in Hasakah, Syria, and has details of the subsequent investigation, in this report narrated by Miguel Amaya.
Video

Video Historic Symbol Is Theme of Vibrant New Show

A new exhibit in Washington is paying tribute to the American flag with a wide and eclectic selection of artwork that uses the historic symbol as its central theme. VOA’s Julie Taboh was at the DC Chamber of Commerce for the show’s opening.

VOA Blogs