News / Health

New Malaria Vaccine Passes Safety Test

Researchers focus on improving effectiveness

Adult mosquitoes feeding on human blood containing malaria parasite.
Adult mosquitoes feeding on human blood containing malaria parasite.

Multimedia

Audio
Art Chimes

The fight against malaria may have taken a promising step forward with the latest tests of a new kind of vaccine, which aims to keep people healthy and prevent the infection from spreading.

Most malaria vaccines under development work by including genetically engineered versions of just a handful of the thousands of proteins of the Plasmodium parasite. Those modified proteins are designed to trigger an immune response to Plasmodium, after it’s passed into the host’s bloodstream by the bite of an infected mosquito.

In contrast, says researcher Robert A. Seder of the U.S. National Institute of Allergy and Infectious Diseases, this new vaccine includes a deactivated version of the entire parasite.

"So instead of picking out one or two or three genes," he says, "you have the potential for what we call breadth - generating an immune response that would be broad rather than narrower. And so that would be a good thing."

Sanaria staff produces the PfSPZ vaccine in the company's clinical manufacturing facility.
Sanaria staff produces the PfSPZ vaccine in the company's clinical manufacturing facility.

Plasmodium goes through many stages in its life cycle. To make this vaccine, scientists use the parasite at the stage - called the sporozoite - when it's ready to infect new hosts. They remove the sporozoite from the mosquito's salivary glands and then subject it to radiation.

That weakens it, so it can't cause malaria symptoms, and can't be transmitted via mosquito to another person, either.

This concept has been known since the 1960s, but Seder says there were practical obstacles that prevented the development of a malaria vaccine.

"The major breakthrough here was that my collaborator, Stephen Hoffman at [vaccine company] Sanaria, developed a method where he could isolate the sporozoites and purify them so that they could administer it as a vaccine to humans. And no one thought that that was possible," he explained.

Adult mosquitoes ready for vaccine production.
Adult mosquitoes ready for vaccine production.

And no one knew if the weakened sporozoites would jump-start the immune system to protect against malaria.

To find out, researchers used human volunteers. The vaccine was injected into their skin with a needle, to simulate the bite of a mosquito. From a safety standpoint, the results were good - there were only relatively minor side effects. But a vaccine must be safe and effective, and this one just wasn't very effective. Only two out of 44 volunteers who got the vaccine were protected when bitten by malaria-infected mosquitoes.

To find out why, the researchers then switched to laboratory animals, and Seder says they concluded that the problem was the way the vaccine was administered.

"Had [Hoffman] given [the vaccinations] in the vein, intravenously, directly in the blood, rather than through the skin, he would have gotten much higher immune responses."

That would be unusual for a vaccine, which is typically given by mouth or as a skin or muscle injection. It also might complicate mass vaccination programs, if the vaccine goes into general use.

Cost is also an issue, but researcher Seder says it's too soon to know how the vaccine will be priced - assuming it is effective.

The next stage of human testing - using intravenous administration - is due to start in October.

You May Like

WHO: Anti-Ebola Efforts Should Focus on West Africa

Official says WHO is 'reasonably confident' countries bordering those hardest hit by the Ebola outbreak are not seeing the virus crossing their borders More

South Sudan Crisis Threatens Development

Economic costs and lost development opportunities in South Sudan have erased what little progress the country has made since independence in 2011 More

Ukrainian PM Warns: Russia May Try to Disrupt Sunday Poll

Arseniy Yatsenyuk orders full security mobilization for parliamentary election to prevent ‘terrorist acts’ from being carried out More

This forum has been closed.
Comments
     
There are no comments in this forum. Be first and add one

Featured Videos

Your JavaScript is turned off or you have an old version of Adobe's Flash Player. Get the latest Flash player.
After Decades of Pressure, Luxembourg Drops Bank Secrecy Rulesi
X
October 21, 2014 12:20 AM
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 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 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 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.
Video

Video Young Nairobi Tech Innovator on 'Track' in Security Business

A 24-year-old technology innovator in Nairobi has invented a tracking device that monitors and secures cars. He has also come up with what he claims is the most robust audio-visual surveillance system yet. As Lenny Ruvaga reports from the Kenyan capital, his innovations are offering alternative security solutions.
Video

Video Latinas Converting to Islam for Identity, Structure

Latinos are one of the fastest growing groups in the Muslim religion. According to the Pew Research Center, about 6 percent of American Muslims are Latino. And a little more than half of new converts are female. VOA’s Carolyn Presutti travelled to Miami, Florida -- where two out of every three residents is Hispanic -- to learn more.
Video

Video Exclusive: American Joins Kurds' Anti-IS Fight

The United States and other Western nations have expressed alarm about their citizens joining Islamic State forces in Syria and Iraq. In a rare counterpoint to the phenomenon, an American has taken up arms with the militants' Syrian Kurdish opponents. Elizabeth Arrott has more in this exclusive profile by VOA Kurdish reporter Zana Omer in Ras al Ayn, Syria.
Video

Video South Korea Confronts Violence Within Military Ranks

Every able-bodied South Korean male between 18 and 35 must serve for 21 to 36 months in the country’s armed forces, depending upon the specific branch. For many, service is a rite of passage to manhood. But there are growing concerns that bullying and violence come along with the tradition. Reporter Jason Strother has more from Seoul.
Video

Video North Carolina Emerges as Key Election Battleground

U.S. congressional midterm elections will be held on November 4th and most political analysts give Republicans an excellent chance to win a majority in the U.S. Senate, which Democrats now control. So what are the issues driving voters in this congressional election year? VOA National Correspondent Jim Malone traveled to North Carolina, one of the most politically competitive states in the country, to find out.
Video

Video Comanche People Maintain Pride in Their Heritage

The Comanche (Indian nation) once were called the “Lords of the Plains,” with an empire that included half the land area of current day Texas, large parts of Oklahoma, New Mexico, Kansas and Colorado.The fierceness and battle prowess of these warriors on horseback delayed the settlement of most of West Texas for four decades. VOA’s Greg Flakus reports from Lawton, Oklahoma, that while their warrior days are over, the 15,000 members of the Comanche Nation remain a proud people.
Video

Video Turkey Campus Attacks Raise Islamic Radicalization Fears

Concerns are growing in Turkey of Islamic radicalization at some universities, after clashes between supporters of the jihadist group Islamic State (IS) or ISIS, and those opposed to the extremists. Pro-jihadist literature is on sale openly on the streets of Istanbul. Critics accuse the government of turning a blind eye to radicalism at home, while Kurds accuse the president of supporting IS - a charge strongly denied. Henry Ridgwell reports from London.

All About America

AppleAndroid