September 26th, 2019

DRC Official Prefers Merck’s Ebola Vaccine

Ebola Zaire vaccine candidate v920 rVSV∆G-ZEBOV-GP reported 97.5% effective

DRC young african boy on the river

The Democratic Republic of Congo's (DRC) Health Minister called for Merck’s experimental Ebola vaccine v920 (rVSV∆G-ZEBOV-GP) to be fully licensed. 

According to Africa Reuters, Dr. Oly Ilunga Kalenga told reporters in Geneva, Switzerland, on May 22, 2019, that “somehow we have to catch up with the DRC outbreak and break the transmission chain very quickly.” 

Dr. Kalenga’s comments are related to Situation Report #42, which says there have been a total of 1,847 confirmed and probable Ebola cases and 1,223 deaths, since August 2018. 

Since the beginning of the DRC vaccination program, approximately 111,920 persons have been vaccinated with Merck’s v920 (rVSV∆G-ZEBOV-GP). 

Additionally, Dr. Kalenga said he ‘preferred to use just one Ebola vaccine, and that adding Jenssen's rival Ebola vaccine candidate Ad26.ZEBOV would complicate matters.’ 

This comment is related to the Strategic Advisory Group of Experts (SAGE) recommendations on May 7, 2019, introducing Jenssen’s Ad26.ZEBOV as an additional Ebola vaccine for the DRC situation. 

Both Ebola vaccines are considered experimental, which means they can be used under strictly controlled research protocols, says the World Health Organization (WHO). 

However, Merck’s v920 vaccine has been used throughout the outbreak and has proven highly effective.

A new analysis published in May 2019 estimated v920’s Vaccine Efficacy at 97.5 percent.

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V920 is a recombinant, replication-competent vaccine, consisting of a vesicular stomatitis virus, which has been genetically engineered to express a glycoprotein from the Zaire ebolavirus so as to provoke a neutralizing immune response to the Ebola virus. 

“It would perturb the population to be faced with several different types of vaccines and that would muddle the message. And, as you know in complex outbreak response, the message needs to be simple and clear.” 

“If the v920 vaccine is licensed, it would be easier. Merck’s licensing process is underway but it was unclear how long it would take,” Dr. Kalenga said. 

In addition to vaccinating contacts and contacts of contacts, WHO’s SAGE now recommends vaccinating those who could be part of tertiary chains of transmission, such as people in villages and neighborhoods where cases have been reported within the past 21 days. 

SAGE also recommended adjusting the dose of the v920 vaccine. 

“The Working Group recognized that the current emergency and the available evidence called for a dose-adjusted approach to ensure vaccine continues to be available and offered to individuals at greatest risk of Ebola,” said Helen Rees, Co-Chair of the SAGE Ebola Vaccines Working Group. 

“The SAGE emphasized that ring vaccination of contacts and contacts of contacts continues to be the preferred strategy.”