WHO Ready For Marburg Vaccine Trials, Awaits Nod From Governments of Tanzania and Equatorial Guinea
A hospital corpsman prepares a flu vaccine
A hospital health worker prepares a vaccine

The World Health Organization (WHO) said that it is poised to begin clinical trials of three Marburg disease vaccine candidates if Tanzania and Equatorial Guinea, both struggling with outbreaks of the deadly disease, give the green light.  About 2000 finished doses are available from vaccine developers and could be administered to the identified contacts of victims of the deadly disease, WHO officials said at a press conference on Wednesday.  

“The WHO Committee has now reviewed the evidence for four vaccines. Trial protocols are ready and our partners are ready to support the trials,” Dr Tedros Adhanom Ghebreyesus, WHO Director-General said at the briefing.  “We look forward to working with the governments of both countries (Tanzania and Equatorial Guinea) to begin these trials to help prevent cases and deaths now, and in future outbreaks.” 

The 2000 doses readily available are distributed among the active vaccine candidates in WHO’s pipeline: Sabin Vaccine Institute has 750 doses ready in vials, the University of Oxford has 1000 doses in vials and Public Health Vaccines has several hundred doses ready to be used immediately. 

This does not include vaccine products available in bulk, which will be available for use later in 2023. 

Explaining the steps forward, Dr Ana Maria Henao-Restrepo, the head of WHO’s R&D Blueprint team, said that the vaccines would be administered in a Phase 3 ”ring vaccination trial”. A ring vaccination trial involves administering vaccines to the close contacts of the infected individual. 

“It’s not that we are saying there are millions of doses out there, but based on our experience, we have sufficient doses to make rings of cases around these infected individuals,” she said. “Typically, Marburg outbreaks are small. The largest was about 300 cases. In the background of these numbers, the developers are working to put the bulk vaccines into vials and to increase their capacity.” 

No global stockpile of vaccines for Ebola Sudan strain or Marburg virus

Doses remain limited insofar as WHO does not yet have a global stockpile of vaccines against Marburg virus disease, or the Sudan strain of Ebolavirus – partly because the vaccines have not yet been approved by regulators for use. 

Tanzania reported its first ever Marburg virus disease outbreak on 21 March 2023, in which it confirmed eight cases, including five deaths. The remaining three infected individuals are receiving treatment. The authorities have identified 161 contacts of the infected individuals and are monitoring them. 

In Equatorial Guinea, nine cases have been confirmed so far across three provinces of the country. While the first three cases were reported in February, subsequent cases were confirmed in March. The distribution of the nine cases is spread across the Kié-Ntem, Litoral and Centro Sur provinces. 

“These three provinces are 150 kilometers apart, suggesting wider transmission of the virus. WHO is aware of additional cases, and we have asked the government to report these cases officially to WHO,” Tedros added.

Initial test results negative for Marburg in Burundi

After three persons died due to a mystery illness in a span of three days in Burundi, the WHO said that the initial test results of samples taken from these individuals have returned negative for Marburg virus disease. 

“In Burundi, we are aware of nine alerts and three of them are already dead. Initial samples were taken when they were alive and showed negative for Marburg, ebola and dengue,” Dr Abdi Rahman Mahamud, director of alert and response coordination department at the WHO said. 

He added that the Burundi government has established sensitive surveillance in the country and that the samples taken have been sent to an advanced laboratory in Uganda for further investigation. 

“As of now, the initial tests are negative, but we know very well there’s a long differential diagnosis. And until we have confirmation from the lab in Uganda and the WHO collaborating centers, all diagnoses are still in place.” 

New COVID-19 variant reported from India

As India reports an increase in COVID-19 cases in the past few days, the WHO said that a new subvariant of the Omicron variant of SARS-CoV-2 has been identified in the country. 

Named XBB.1.16, the newest subvariant Omicron is very similar to the XBB.1.5 subvariant, but is more infectious and has potential increased pathogenicity. 

Dr Maria van Kherkhove, WHO’s Covid-19 technical lead.

“There are only about 800 sequences of XBB.1.16 from 22 countries. Most of the sequences are from India, and in India, XBB.1.16 has replaced the other variants that are in circulation. So this is one to watch. It’s been in circulation for a few months,” Dr Maria van Kerkhove, the technical lead for COVID-19 at WHO said. 

India reported 2151 new cases of COVID-19 in the last 24 hours, which is the highest the country has seen in five months.

Reiterating that COVID-19 is still a Public Health Emergency of International Concern (PHEIC) at a global level, Dr van Kerkhove said that it is imperative to remain vigilant. 

The agency’s Strategic Advisory Group of Experts on Immunization (SAGE), meanwhile, said that additional COVID-19 vaccine boosters are not recommended for individuals with low to medium risk, if they are already vaccinated and boosted once. 

For “high priority” categories, SAGE recommended that an additional booster dose be administered once in six to 12 months after the previous dose. 

Image Credits: Flickr.

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