The physician, given the vaccine 43 hours after the needle stick
injury, went on to show a clinical syndrome "consistent with vaccination response, and no evidence of Ebola virus infection was detected."
Known as VSVΔG-ZEBOV, the treatment was injected into the doctor-patient's muscle as he was boarded onto a flight back
to the US.
During transit 12 hours after the injection, malaise, nausea and fever set in. Care following at the special clinical studies unit of the National Institutes of Health in Bethesda, MD, observed this sequence:
On arrival, "mild to moderate distress" because of fever,
nausea, malaise, muscle pain and chills
On day 2, reduced fever but continuing severe symptoms
accompanied by mild nausea and joint pain (arthralgia)
Days 3 to 5, symptoms and laboratory abnormalities subsiding
By day 7, all symptoms completely gone.
Throughout, lab tests also took regular measures of the patient's immune cell, antibody and protein levels - "strong innate and Ebola-specific adaptive immune responses were detected after vaccination," the researchers found.
The 44-year-old American doctor had received his injury when
placing a needle into a sharps bin - it "inadvertently punctured two layers of gloves and caused bleeding of the left thumb."
The needle "had just been in direct contact with severely ill
Ebola patients" and the exposure was estimated to pose a
significant risk of infection for the doctor.
"The patient experienced a transient febrile syndrome after
vaccination," says Thomas Geisbert, PhD, in his editorial
article about the case. He reiterates the researchers' findings: "Importantly, no evidence of Ebola virus infection was detected, and the vaccine elicited strong innate and Ebola virus-specific adaptive immune responses."
"Most significantly," Dr. Geisbert adds, the vaccine gave
an immune response in the patient at a level that had been
shown in tests on primates to confer protection against the
virus.
Laboratory tests on the doctor showed the vaccine expressed the surface glycoprotein of the Ebola virus, which was able to
induce a "sufficient level" of a certain type of antibody response to the glycoprotein.
Success in animals should be advanced to humans 'urgently'
"Although it is not possible to know with absolute certainty"
whether the vaccine used to treat this single case of "potential high-risk exposure" had any influence on the patient's survival, Dr. Geisbert says, "this incident serves as an example of how important it is to have safe and effective countermeasures available in sufficient quantities that can be rapidly deployed for
emergency use for both medical workers and affected populations."
A number of vaccines and postexposure treatments have made "substantial progress" in animal studies, but advancement of these for human use "is a matter of utmost urgency," Dr.
Geisbert adds - none is yet licensed for use in people.
This is just the second time a person has been given VSVΔG- ZEBOV for postexposure treatment; its first use in a human was in 2009 for an Ebola lab worker.
The authors of the present case study - Dr. Mark Mulligan of
Emory University in Atlanta, GA, and colleagues - note, however, that four early-phase clinical trials were started in 2014 - although the results are as-yet secret.
The authors also cite a trial that has just begun in Liberia, with enough promise from this confidential information to
investigate the vaccine for use in pre-exposure prevention of
Ebola - aiming, that is, to protect people who have not been
infected with the virus but are at risk.
The authors say there are unknowns in the physician's case that will need to be considered for future experimental treatment.
"In the current patient, a self-limited, moderate to severe clinical syndrome began at 12 hours postvaccination."
At the end of January, the World Health Organization said the
Ebola fight 'had shifted to ending the epidemic' in the West
African countries affected.
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