Stories
Slash Boxes
Comments

SoylentNews is people

posted by martyb on Tuesday September 18 2018, @04:25AM   Printer-friendly
from the what-could-possibly-go-wrong? dept.

In 2016, as the mosquito-borne Zika virus spread through the Americas and cases of infected women having brain-damaged babies mounted, investigators raced to develop a vaccine. Now, a $110 million vaccine trial is underway at 17 sites in nine countries, but it faces an unexpected, and ironic, challenge. Cases of Zika have plummeted to levels so low that most people vaccinated in the trial likely will never be exposed to the virus, which could make it impossible to tell whether the vaccine works.

"Right now, there are no infections, and certainly not enough to even think about an efficacy signal at this point," says Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases (NIAID) in Bethesda, Maryland, which launched the trial. Human trials of other Zika vaccine candidates at earlier stages are also in limbo, and last year one large vaccinemaker pulled the plug on development of its candidate. But NIAID and others are pressing ahead, saying a vaccine might someday be needed. To make up for the lack of new cases, other investigators are turning to an unusual, and ethically complex, strategy. Starting next year, Science has learned, they plan to test a vaccine by deliberately infecting people with Zika.

Launched in March 2017, NIAID's placebo-controlled vaccine trial includes two sites in Brazil, where Zika hit hardest and where the brain damage known as microcephaly first surfaced. From the beginning of the outbreak in 2015 until the start of this year, Brazil had about half of all 800,000 suspected and confirmed Zika cases in the Americas, according to the Pan American Health Organization in Washington, D.C. But from January through June, Brazil's Ministry of Health reported fewer than 7000 probable cases, in a nation of 200 million people. "It's a good dilemma because we don't have Zika anymore," says Esper Kallás of the University of São Paulo in São Paulo, Brazil, principal investigator for the local NIAID site. "But it's a dilemma. Everybody is concerned about it. It's a lot of investment."

[...] Given the drop in cases, a surer way to test any vaccine against Zika is to deliberately expose inoculated subjects to the virus. Researchers have used this strategy, known as a human challenge trial, for decades to test vaccines against diseases that either can be effectively treated or, like Zika, typically cause mild symptoms.

But in 2017, an ethics committee convened by NIAID and the Walter Reed Army Institute of Research in Silver Spring, Maryland, called it "premature" for Zika. They worried that people intentionally infected with the virus might transmit it to their sexual partners, primarily through infected semen. And they were confident that traditional field trials could test the efficacy of the leading vaccine candidates.

[...] Now, the study is being considered again, as Zika disappears from the region and industry loses interest in bringing a vaccine to market. In a major blow, Sanofi Pasteur halted work on its vaccine, licensed from Walter Reed, in September 2017. "There's a compelling reason to conduct a human challenge trial now," says bioethicist Seema Shah of Northwestern University's Feinberg School of Medicine in Chicago, Illinois, who chaired the 2017 ethics committee. But, she adds, "The details are complicated and it's important to have a rigorous review."

"If they're careful, we have no problems supporting it," Fauci says. Durbin plans to submit her new protocol for review in about a month, and in early 2019 hopes to start injecting Zika virus into people immunized with a vaccine containing live, but weakened Zika virus made by NIAID's Stephen Whitehead. As a precaution, she plans to enroll only women at first, to avoid semen transmission from infected males. The volunteers will receive a low dose of Zika virus, and they will remain in clinics for the 2 weeks it typically takes to clear the infection. Any vaccine that works in the challenge study theoretically could then be evaluated in a real-world outbreak—just as is occurring now with an unlicensed but promising Ebola vaccine.

doi:10.1126/science.aav3996

-- submitted from IRC


Original Submission

 
This discussion has been archived. No new comments can be posted.
Display Options Threshold/Breakthrough Mark All as Read Mark All as Unread
The Fine Print: The following comments are owned by whoever posted them. We are not responsible for them in any way.
  • (Score: 2) by c0lo on Tuesday September 18 2018, @07:50AM

    by c0lo (156) Subscriber Badge on Tuesday September 18 2018, @07:50AM (#736422) Journal

    Which sex produces semen, again?

    Runaway1956... by his very nature of being a self-confessed seaman... I reckon it's seaman stains all around him

    (large grin)

    --
    https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
    Starting Score:    1  point
    Karma-Bonus Modifier   +1  

    Total Score:   2