Ebola doctor who received vaccine after needle accident is virus-free

By Fiona BARRY

- Last updated on GMT

Ebola survivors welcome the UN Secretary-General at an Ebola treatment unit in Hastings, Sierra Leone last December. (Image: Martine Perret/UN)
Ebola survivors welcome the UN Secretary-General at an Ebola treatment unit in Hastings, Sierra Leone last December. (Image: Martine Perret/UN)

Related tags Ebola vaccine Immune system Ebola Vaccine

A doctor whose thumb was punctured by a needle while working with Ebola patients in Sierra Leone received Merck & Co.’s vaccine candidate and did not develop the virus.

The 44 year-old American physician was injured and possibly exposed to the virus on September 24, 2014 at an Ebola treatment centre. He was evacuated to the US and received Merck-NewLink’s Ebola vaccine VSVΔG-ZEBOV within 43 hours.

The doctor developed fever and other moderate-to-severe symptoms within 12 hours of receiving the vaccine – effects which lessened over the next three to four days.

Tests showed he had an immune response to the vaccine but remained negative for the Ebola virus nucleoprotein gene, which is not in the vaccine.

The doctor was injured while placing a hollow-bore needle that had vented a plastic intravenous bottle into a sharps bin when he accidentally punctured two layers of gloves and pierced his left thumb, which began bleeding.

His outer gloves were not visibly dirty but had just been in direct contact with severely ill Ebola patients, including one with a very high Ebola virus RNA level.

Standard procedures for taking off protective equipment delayed the doctor for ten minutes before he could wash the wound with bleach and soap.

Does the vaccine work?

VSVΔG-ZEBOV is a replicating attenuated recombinant vesicular stomatitis virus (serotype Indiana) which uses the Zaire Ebola virus glycoprotein gene. The candidate, developed by Merck & Co. and NewLink with the support of the Public Health Agency of Canada, entered Phase III trials on March 7.

An emergency Investigational New Drug application freed up the vaccine for the injured doctor. Results from the compassionate use of VSVΔG-ZEBOV in the Sierra Leone case can be used to complement the larger trial, said Sanjeev Krishna, Professor of Molecular Parasitology and Medicine, St George’s, University of London.

While results were positive for the American doctor, a paper published in the Journal of the American Medical Association​ concluded it is still “unknown if VSVΔG-ZEBOV is safe or effective for post-exposure vaccination in humans who have experienced a high-risk occupational exposure to the Ebola virus, such as a needle stick.

In this patient, post-exposure vaccination with VSVΔG-ZEBOV induced a self-limited febrile syndrome that was associated with transient detection of the recombinant vesicular stomatitis vaccine virus in blood.

Strong innate and Ebola-specific adaptive immune responses were detected after vaccination. The clinical syndrome and laboratory evidence were consistent with vaccination response, and no evidence of Ebola virus infection was detected.​”

Other workers exposed

The September incident is the second time an experimental Ebola vaccine has been used to try to prevent infection after accidental exposure, according to Jonathan Ball, Professor of Molecular Virology, University of Nottingham. Ball added the sample size was too small to know whether the vaccine was responsible for the doctor’s positive results.

Even though the person didn’t get infected, we can’t be sure if it was the effect of the vaccine or that the exposure wasn’t sufficient to cause an infection in the first place.

“You could only work out if the vaccine is useful if you had comparative data for a larger number of people who had similar exposure, and some did and others did not receive a vaccine.  Comparing the proportion that eventually develops infection would give you an idea if the vaccine worked.

Whether or not such ‘post-exposure prophylaxis’ should be offered routinely is difficult to say, especially when we don’t yet know if the vaccine works. Sure, the vaccine elicited a strong immune response, but we have no idea if this can protect against infection. This is the key issue that we need to find out.​”

Source: Emergency postexposure vaccination with vesicular stomatitis virus–vectored Ebola vaccine after needlestick​ by Lilin Lai et al​, JAMA​, March 5, 2015.


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