Ring of Fire: Can New Vaccine Stop Ebola?

June 11th, 2018

By Gary Evans, Medical Writer

As healthcare workers and case contacts are vaccinated against the Ebola virus in the Democratic Republic of Congo, U.S. healthcare facilities are being warned to watch vigilantly for travel cases linked to the ongoing outbreak.

“U.S. healthcare facilities should continue to seek travel histories as a routine part of initial patient triage and assessment,” says Kate Fowlie, a spokeswoman for the Centers for Disease Control and Prevention. “In the context of the current outbreak, travel to the Ebola-affected health zones in the DRC or contact with an individual with confirmed Ebola within the previous 21 days should trigger further symptom evaluation.”

Now is a good time for facilities to review their status as front-line, assessment, or treatment centers, and confirm that current health department contact information is readily available, she adds. The CDC recommends a strategy of “Identify, Isolate, and Inform,” which calls for immediately isolating suspected Ebola cases and alerting the facility’s infection preventionist and the health department.

For PPE, CDC recommends following the CDC guidance for U.S. healthcare settings that was developed during the 2014-2015 outbreak. Some 11,000 people — including one in the U.S. — died during that outbreak, which also involved the Zaire strain of the Ebola virus. The index case for the current outbreak in the Congo was reported on April 4, 2018. As of June 9, 2018, there have been a total of 66 Ebola cases and 28 deaths, leading to a mortality rate of 42%. Of the 66 cases, 38 have been laboratory confirmed, 14 are probable (deaths for which it was not possible to collect laboratory specimens for testing), and 14 are suspected, the World Health Organization reports.

An experimental vaccine called rVSV-ZEBOV was found to be highly protective against the virus in a trial conducted by the WHO in Guinea in 2015. The vaccine has not been licensed by the FDA yet.

“Ebola vaccines remain investigational products, and there is currently no recommendation about pre-exposure vaccination of U.S. healthcare personnel,” Fowlie says.

Healthcare workers in the Congo and contacts of cases are being vaccinated in the classic ring approach that was used to eradicate smallpox. In a triumph of genetic engineering, the vaccine consists of an animal vesicular stomatitis virus seeded with the protein of Zaire Ebola. It provokes a human immune response to the Ebola virus.

For vaccination purposes, contacts with an Ebola case include those living in the same household or those who were visited by the patient in the three weeks prior to diagnosis. Further, “contacts of contacts,” including neighbors or extended family members, may also be vaccinated.

“The ring is not necessarily a contiguous geographic area but captures a social network of individuals and locations that may include dwellings or workplaces further afield, where the index patient spent time while symptomatic, or the households of individuals who had contact with the patient during the illness or after his or her death,” the WHO stated. “Experience suggests that each ring may be composed of an average of 150 persons.”

No Ebola cases were being treated in the U.S. as this report was filed, but the CDC has deployed eight experts to the region to assist in the outbreak. The CDC has posted a Level 1 Watch travel notice for Ebola in DRC.

“We are monitoring the outbreak and are not currently recommending people avoid travel,” Fowlie says.

Although the risk to most travelers is low, visitors to the Congo should avoid contact with blood or body fluids, funeral or burial rituals that require handling a dead body, raw bush meat, and wild animals. The 2014 outbreak was thought to have begun with a child who was playing in a hollow tree full of bats, which can asymptomatically carry the virus.