By Paul Adepoju
The World Health Organization and the Africa Centres for Disease Control and Prevention said that the findings of the studies are expected to bring about policy changes in the continent’s response to Ebola to include children in vaccination campaigns.
In May 2014, the government of Sierra Leone announced an Ebola outbreak, and as it was responding to the outbreak, clinical trials targeting adults and children in Sierra Leone’s Kambia district for Johnson & Johnson’s two-dose Johnson Ebola vaccine regimen — called Ad26.ZEBOV and MVA-BN-Filo vaccines — were planned to test the safety and effectiveness of the vaccine.
During the 2014-2016 outbreak of Ebola in West Africa, 28,652 cases and 11,325 deaths were reported. Approximately 20% of cases were in children under 15, and children younger than 5 years old are at a higher risk of death than adults.
Before the trials eventually commenced, the outbreak had slowed down and the team of researchers led by Dr. Muhammed Afolabi and Dr. Daniela Manno, both from the London School of Hygiene & Tropical Medicine, had to pivot the goal of the study from testing for effectiveness to its safety and ability to generate strong immune responses.
Working with the health authorities in Sierra Leone, the researchers recruited children and adults in separate studies. According to the findings published in The Lancet Infectious Disease Journal — the vaccine was found to be safe and generated adequate immune responses in both adults and children.
The first study found the vaccine regimen was well tolerated and induced antibody responses to Zaire ebolavirus 21 days after the second dose in 98% of adult participants, with the immune responses persisting for at least two years.
Among children aged 1 to 17, the second study found the vaccine was “well tolerated with no safety concerns,” and “induced robust humoral immune responses, suggesting the suitability of this regimen for Ebola virus disease prophylaxis in children.”
Ebola virus antibody responses were observed in 98% of children aged 12 to 17, 95% of children aged 4 to 11, and in 98% of children aged 1 to 3, 21 days after receiving the second dose of the vaccine.
Afolabi told Devex the evidence provided by the study is expected to bring about policy changes including the inclusion of children as young as 1 in Ebola vaccination programs.
“The results show that this vaccine regimen has the potential to save many young lives,” Afolabi said.
The vaccine is currently administered through a ring vaccination approach in which adult contacts of suspected cases and front-line health workers are given the doses. Children below the age of 17 are excluded due to a lack of data regarding safety and efficacy in children.
The studies also reported evidence that booster doses of the vaccine could increase protection.
“Booster dose[s] produced a rapid and strong increase in antibody concentration. This supports the recommendation of the provision of a booster dose in previously vaccinated people when there is an imminent risk of Ebola infection,” Manno said.
From years to months: How the Ebola response is getting better
Ebola outbreaks are now contained in a matter of months, as opposed to what previously took years. Over the weekend, Guinea was declared Ebola-free and so was the African continent.
Researchers are also carrying out further studies in Sierra Leone to investigate whether the vaccines are safe and induce immune responses among infants aged under 1, and to follow up with the adult and child participants over 5 years old to assess the potential for long-term protection.
Last month, WHO announced that front-line health workers, practitioners of traditional medicines or traditional healers, and commercial motorbike riders who received the first dose of the vaccine were being given their second jab to maximize their protection against the disease.
For the exercise, the target beneficiaries were those that had been identified as high-risk groups and selected for preventive vaccination to protect them in the event there was a cross-border transmission of the disease, which had re-emerged in Guinea in February 2021.
Over 16,000 beneficiaries including health workers, and high-risk groups in border communities and the major referral public and private hospitals were prioritized for the preventive vaccination.
Reacting to the findings of the Ebola vaccine clinical trial, Dr. Matshidiso Moeti, WHO regional director for Africa, said the study findings were “extremely good news.”
“This is a vaccine that can be used more broadly, including protecting children from being infected by Ebola, so this is a very important finding that can be worked into the process of preparing supplies,” she said.
Dr. John Nkengasong, director of Africa CDC also called for the revision of Ebola prevention and control policy guidelines in the continen