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Insufficient evidence to recommend Ebola vaccine for pregnant women, WHO advisory group says
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A committee that advises WHO on global immunization policy said there is insufficient evidence to recommend giving pregnant women an experimental Ebola virus vaccine — a timely issue given the ongoing deadly Ebola outbreak in the Democratic Republic of the Congo.
Research has showed that almost 90% of pregnant women infected with Ebola die from the disease, and there is only one documented case of a child born to an infected mother surviving for longer than 1 month.
The DRC has approved the use of an experimental Ebola vaccine, V920 (Merck), in two separate outbreaks this year, including the ongoing outbreak in North Kivu province. But protocol prevents the vaccine from being given to children younger than age 6 years and pregnant or lactating women because of limited data in these groups, although there is evidence they may be indirectly protected via a ring vaccination approach like the one being used in the DRC, according to WHO.
Data viewed by the Strategic Advisory Group of Experts on Immunization (SAGE) showed that a number of women have been inadvertently vaccinated while pregnant, and have been followed up, “but this is a small group and does not allow us to reach any clear conclusions” about the safety of vaccinating pregnant women, SAGE chair Alejandro Cravioto, MD, PhD, said during a press briefing following several days of meetings. He added that SAGE expects follow-up studies soon on the women who were inadvertently vaccinated while pregnant.
“Given the current evidence that we have, there is no conclusion on this subject,” Cravioto said.
SAGE members reviewed phase 2 studies of an Ebola vaccine being developed by Johnson & Johnson and its plans to develop the vaccine for use in humans, but data were not available regarding that vaccine, Cravioto said.
Martin Friede, PhD, the director of the Department of Immunization, Vaccines and Biologicals at WHO, noted that the Merck vaccine is the only one that has demonstrated efficacy in the field. “We have very good data showing the impact of vaccination with the recombinant VSV vaccine,” he said
He added that there are promising Ebola candidates in the pipeline, including some that are two-dose vaccines.
“We want to encourage the manufacturers to bring these vaccines forward,” Friede said. “The challenge is how will these manufactures show efficacy,” since this would require an outbreak.
Regarding other vaccines, SAGE executive secretary Joachim Hombach, PhD, MPH, said there is a “constraint of supply” of HPV vaccines and that SAGE is working with manufacturers to ramp up production to reach the needed populations.
“The vaccine implementation should focus on countries with the highest levels of cervical cancer,” he added.
Cravioto addressed the goal of polio eradication programs, asking: “How do we complete the task?” He said the current production of vaccines has allowed all children being born to receive vaccinations. There is a continued need for surveillance with polio vaccination, Cravioto added.
Hombach gave an update on measles immunization, noting the many outbreaks that have occurred globally in the past several years.
“Measles is clearly one of the diseases that was singled out in the report on the global vaccine action plan and our achievements. We have seen major measles outbreaks in the past year, particularly in Venezuela,” he said. “That led SAGE to highlight the fragility of the gains” that have been made in measles prioritization.
Cravioto also addressed the impact that migration has on immunization strategies, noting that it was not a factor in SAGE’s original plans for how to deal with children and vaccination programs. – by Bruce Thiel
Disclosures: Cravioto, Friede and Hombach report no relevant financial disclosures.