Blog | Friday, April 17, 2015

Post-exposure vaccination for Ebola

The ongoing Ebola virus outbreak in West Africa continues to underscore the importance of a strong international public health infrastructure and continued investment in both basic and clinical research targeting infectious pathogens. The first line of defense for infectious diseases, if available, is a safe and effective vaccine. However, approved vaccines do not exist for many pathogens like Ebola, so well-designed personal protective equipment becomes critical. But even the best available personal protective equipment can't protect us from sharps injuries. Which brings us to a fascinating case report of post-exposure vaccination of a physician with a needle stick injury obtained while working in an Ebola treatment center in Sierra Leone.

The report by Lilin Lai and colleagues was published online in JAMA along with a very well-written editorial. The 44-year-old physician from the U.S. was stuck by an 18-guage hollow-bore needle through 2 layers of gloves after caring for Ebola patients with very high viral loads. Because doffing procedures had to be followed, there was a 10-minute delay in cleaning the wound with bleach, soap/water and chlorhexidine gluconate. The patient was evacuated and while boarding the jet received an experimental vaccine, a first-generation recombinant vesicular stomatitis virus-based Ebola vaccine (VSVΔG-ZEBOV) 43 hours post-exposure.

Post-vaccination, he developed fever and malaise but made it safely to the National Institutes of Health Clinical Center for further care and evaluation. His course was a bit rocky the first few days with fever, lymphopenia and diminished oxygen saturations, but symptoms and signs slowly improved over 3 to 5 days and he was asymptomatic by day 7. He was discharged to complete the 21-day mandatory isolation-period at home. Ebola virus was never detected.

You can read the full report (free online) if you're interested in the many tables and figures outlining his immune responses. Briefly, the vaccine did elicit a strong innate and virus-specific immune responses. Most importantly (per the editorial) it was “able to induce an IgG antibody response against the Ebola virus glycoprotein at a level that has been associated with protection of nonhuman primates.” However, the editorial correctly notes that no definitive conclusions can be drawn since it is unclear if the patient was ever infected with the virus and the adverse events the patient experienced could have been secondary to his concurrent travelers' diarrhea.

What is important is that while numerous candidate Ebola vaccines have been shown to effectively prevent transmission in nonhuman-primate models, post-exposure treatments and vaccines have been harder to develop. I wonder if a trial seeking to reduce sharps injuries in Ebola-treatment settings is in the works or if NIH would fund such a trial? Last time I checked, sharps injuries were on the rise, so investment in prevention research remains critical.

Eli N. Perencevich, MD, ACP Member, is an infectious disease physician and epidemiologist in Iowa City, Iowa, who studies methods to halt the spread of resistant bacteria in our hospitals (including novel ways to get everyone to wash their hands). This post originally appeared at the blog Controversies in Hospital Infection Prevention.