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WHO issues new Ebola vaccine recommendations

The World Health Organisation’s Strategic Advisory Group of Experts (SAGE) has issued new recommendations to address vaccination challenges in the ongoing Ebola outbreak in the Democratic Republic of the Congo (DRC). The recommendations include endorsing operational adjustments that make the vaccination process faster and adjusting the dosage based on available efficacy data. The SAGE also suggested expanding the population eligible for vaccination with rVSV-ZEBOV-GP (developed by Merck & Co), introducing an additional experimental vaccine (developed by Johnson & Johnson), and redoubling ongoing efforts to train nurses, doctors and medical students from Ebola-affected communities to work on vaccination teams.

More than 111,000 people have been vaccinated in the DRC since the outbreak was declared in August 2018. However, despite the use of a highly efficacious vaccine, the number of new cases continues to rise, in part due to repeated incidents of violence affecting the ability of response teams to immediately identify and create vaccination rings around all people at risk of contracting Ebola.

“We know that vaccination is saving lives in this outbreak,” said WHO director-general Dr Tedros Adhanom Ghebreyesus. “We also know that we still face challenges in making sure the contacts of every case receive the vaccine as soon as possible. These recommendations account for ongoing insecurity and incorporate feedback from experts and from the affected communities that will help us continue to adapt the response.”

Professor Jean-Jacques Muyembe, director of the National Institute for Biomedical Research (INRB)  and principle investigator for the rVSV ZEBOV Ebola vaccine protocol, also welcomed the recommendations. “The DRC Presidential Commission on Ebola highly appreciates the new SAGE recommendations for the rVSV- ZEBOV GP vaccine,” said Muyembe. “This will allow us to address the increasing demand for this vaccine from the communities. In my role as the principal investigator of this study, I will work with the teams to ensure the recommendations are implemented as soon as possible.”

The SAGE endorsed the use of pop-up and targeted geographic approaches to vaccination when appropriate. These vaccination approaches have already been used successfully in the field by WHO to make the ring vaccination process faster, more secure, and more responsive to community feedback.

In view of the fact that insecurity limits the time that vaccination teams can spend in some communities, and in response to community requests, SAGE recommended steps to streamline implementation of the vaccination protocol. SAGE also endorsed a modified follow-up for safety monitoring.

In addition to vaccinating contacts and contacts of contacts, SAGE now also recommends vaccinating those who could be part of tertiary chains of transmission, such as people in villages and neighbourhoods where cases have been reported within the past 21 days. SAGE noted that increasing access to vaccination in the broader community may help enhance community acceptance of the vaccine and other control measures.

SAGE also recommended adjusting the dose of the vaccine currently being used. “The SAGE emphasised that ring vaccination of contacts and contacts of contacts continues to be the preferred strategy. However, the working group recognised 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.

People at highest risk (contacts and contacts of contacts) will now receive 0.5ml of vaccine instead of 1ml. This dosage is equal to that used in the successful Ebola ça suffit ring vaccination trial in Guinea in 2015, and is expected to provide the same level of protection.

Those for whom a rapid evolution of the immune response is less critical (people who are considered lower-risk / those who could be potentially involved in tertiary transmission) will receive 0.2ml (1/5 of the current dose).

Use of additional Ebola vaccines: plans for deployment of an additional vaccine underway

The SAGE reiterated its previous stance stating the need to assess additional Ebola vaccines. SAGE now additionally recommends offering an alternative vaccine (other than rVSV-ZEBOV-GP) to those at lower risk within affected health areas.

Proposed studies should be scientifically and epidemiologically justified, have appropriate approvals including from all relevant national and other regulatory and ethics authorities, and have defined endpoints suitable for licensure.

The adenovirus 26 vectored glycoprotein / MVA-BN (Ad26.ZEBOV/MVA-BN) investigational Ebola vaccine, developed by Johnson & Johnson, is being considered and a coalition led by the Coalition for Epidemic Preparedness (CEPI) and the London School of Hygiene and Tropical Medicine, and other partners, with support from WHO, are at an advanced stage towards the deployment and assessment of this vaccine.

WHO and partners are working to further engage Congolese nationals from within Ebola-affected communities. The goal is that by end of the month a majority of vaccination team members are healthcare workers, doctors and medical students from affected communities who also speak the local languages.

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