Ebola vaccines demonstrate long-lasting immune response
Vaccines developed in response to the West African Ebola epidemic generated an immune response lasting for at least 2 1/2 years, according to findings presented at the annual meeting of the American Society of Tropical Medicine and Hygiene.
“We were able to detect consistent immune responses in people given candidate Ebola vaccines for up to 3 years after they were vaccinated,” Katie J. Ewer, PhD, an associate professor and immunologist in the Jenner Institute at the University of Oxford, told Infectious Disease News. “This is the first time, really, that we’ve been able to show this.”
The three experimental Ebola vaccines studied by Ewer and colleagues target Ebola Zaire, the virus species associated with two outbreaks in the Democratic Republic of the Congo this year. One of the three, V920 (Merck), has been used in both outbreaks under emergency protocols, including the ongoing outbreak in North Kivu province, one of the largest ever.
The other two combinations used replication-deficient viruses ChAd3 (GlaxoSmithKline) and AdHu26 (Janssen) to prime and the multivalent MVA BN-Filo (Bavarian Nordic) to boost, according to the study abstract.
Of the participants who received MVA/AdHu26, more than three-quarters had positive glycoprotein-specific IgG titers 2 1/2 years later, Ewer and colleagues reported. They observed similar outcomes in 74% of 13 participants who received ChAd3/MVA.
The researchers also measured the effect of V920 in samples from a cohort of 26 contacts of a health care worker in the United Kingdom who was infected with Ebola in Sierra Leone and recovered, but then relapsed. The contacts received the vaccine in October 2015 and again more than three-quarters maintained positive antibody responses after 2 1/2 years.
According to Ewer, their study of the three Ebola vaccines could impact the development of vaccines for other infectious diseases such as Lassa fever, Nipah virus and MERS coronavirus, which all have the potential to cause outbreaks.
“This is really encouraging data, not just for Ebola vaccines but for other outbreak pathogen diseases as well,” Ewer said.
Health care workers operating in outbreak areas of the DRC were the first to receive the Merck vaccine this year. Ewer and colleagues stressed the critical need to protect these workers before an outbreak is confirmed.
“What we need to do is vaccinate health care workers in regions of the world where we know outbreaks are likely to happen,” Ewer said. “We want to do that as part of a rolling program of immunization. Really what we’re looking at here is whether we can use these vaccines to protect health care workers who are in regions at risk rather than just having vaccines that we can use in the response phase of an outbreak.” – by Marley Ghizzone
Ewer KJ, et al. Abstract 685. Presented at: Annual Meeting of the American Society of Tropical Medicine and Hygiene; Oct. 28-Nov. 1, 2018; New Orleans.
Disclosure: Ewer reports no relevant financial disclosures.