Zaire Ebola vaccine generates antibody response as early as 14 days

Results from two randomized trials conducted in West Africa show that three vaccine regimens for Zaire Ebola virus disease (EVD) elicited antibody responses in adults and children.

At 12 months, 41% of adults and 78% of children responded to the Ad26-MVA regimen (Ad26.ZEBOV followed by MVA-BN-Filo after 56 days), and 76% and 87% responded to the rVSV regimen. reacted. (rVSVΔG-ZEBOVGP followed by placebo), 81% and 93% responded to the rVSV booster regimen (rVSVΔG-ZEBOVGP at another dose after 56 days), compared with 3% and 4% in the placebo group, respectively (P.<0.001 for all comparisons to placebo), reported the researchers of the PREVAC research team.

“Immune responses were induced by day 14 after injection of these vaccine regimens and were maintained for 12 months,” the authors wrote. New England Journal of Medicine.

They found that the peak proportion of responding participants was observed at 3 months (28 days after receiving the second dose) in both adults and children in the Ad26-MVA group and at day 28 in both the rVSV group. Note that it was observed that Day 63 for adults and 3 months for children in the rVSV booster group.

Although these results add to the evidence for immunogenicity and safety of the Ad26-MVA regimen and the rVSVΔG-ZEBOVGP vaccine in adults and children, there is no universally agreed correlation of protective immunity to EVD. Rather than assessing disease protection given that there were no cases of EVD in this study,” the team wrote.

“However, levels of glycoprotein-binding antibodies have been shown to strongly correlate with neutralizing antibody titers in non-human primates and humans,” they added. Analyzes based on immunogenicity data, such as those reported, will help evaluate vaccination strategies against EVD.”

Vaccines are often only distributed when an Ebola epidemic occurs, so it’s important to know that the response will be in 14 days, they noted. It was important to investigate the early kinetics of the antibody response, given that it was administered during the outbreak to populations at risk of infection.”

To this end, “Both vaccination with rVSVΔG-ZEBOVGP and Ad26.ZEBOV increased geometric mean antibody concentrations from day 14,” they wrote.

Zaire’s EVD was first identified in Guinea in March 2014 and has spread to Liberia and Sierra Leone, killing 11,000 people across those countries.

Ebola virus transmission to humans is not fully understood, but it occurs through exposure to infected animals, direct contact with blood and other bodily fluids, and exposure to environments contaminated by these bodily fluids. It is thought to spread from person to person through indirect contact with .

Researchers used the PREVAC protocol to compare three vaccine regimens to placebo separately in adults and children. The study was conducted at his six locations in his four countries in West Africa.

Participants were followed up on Days 7, 14, and 28 after Dose 1 to assess antibody responses, responses, and symptoms. .

Most injection site reactions and symptoms were predominantly grade 1 in severity and were reported during the first week after vaccination.

In adults, serious adverse events were reported in 4% of the Ad26-MVA group, 2% of the rVSV group, and 1% of the rVSV booster and placebo groups. Six adults died, none of which were thought to be related to the vaccine or placebo.

In children, serious adverse events were reported in 1% of the Ad26-MVA group, 2% of the rVSV and placebo groups, and 1% of the rVSV booster group. Five children died, and all deaths were unrelated to vaccine or placebo.