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NEW ORLEANS -- A single dose of the cholera vaccine Vaxchora led to a four-fold or higher increase from baseline in serum vibriocidal antibody (SVA) titer in children and teens, results of a randomized trial indicated.
The primary endpoint of the SVA seroconversion rate at day 11 was 98.8% for ages 12-17 years and 96.6% for ages 6-11 years, reported Sean Bennett, MD, PhD, of vaccine maker PaxVax in San Diego, at the .
Vaxchora is currently approved for adults and primarily indicated for those traveling to cholera-endemic areas. PaxVax is hoping to obtain a pediatric indication.
These are the first data for this population, Bennett explained in his presentation, noting that infection challenge studies like those conducted in adults would be unethical in children.
He told ľֱ that immunogenicity data in children at low risk for natural infection -- which is what the current trial provided -- should be adequate to win regulatory approval. Nevertheless, he added, PaxVax plans to conduct additional pediatric studies in cholera-endemic areas to assess protection against disease. That's because the company sees demonstration of real-world clinical efficacy as part of its "social mission," he said, and more practically because organizations that conduct cholera vaccinations on the ground want to see such data before agreeing to use the product.
To fill the knowledge gap, the present study assessed Vaxchora in U.S. children and adolescents receiving a single dose, focusing on safety and immunogenicity.
Boys and girls ages 6-17 years who were in good health were enrolled, with 175 ages 6-11 and another 175 ages 12-17, who were analyzed separately. The study participants were screened over the course of 30 days, then researchers followed up for 181 days after dosing.
For both age ranges, 150 patients received the vaccine and 25 got placebo. Geometric mean vibriocidal antibody titers were measured through day 181 for ages 12-17 and through day 29 for ages 6-11.
When followed out to day 181 in the older group (Bennett said the company plans to continue follow-up for 2 years), mean antibody titers declined by about half by day 91 but then declined only a little more at the last measurement. Titers at that point were still considered protective.
Almost 70% of participants 12-17 years old showed "solicited" adverse events (which Bennett did not discuss in detail), but nearly all were considered mild. Such events were seen in just over 50% of the younger group. These rates were comparable to those seen in adults, he said. Diarrhea, vomiting, and fever were infrequent, Bennett said.
Looking ahead, the researchers intend to publish their findings. A study in children age 2-5 is also getting underway, Bennett said.
Disclosures
The clinical trial is sponsored by PaxVax. Bennett is a PaxVax employee.
Primary Source
American Society of Tropical Medicine and Hygiene
Bennett S, et al “A single dose of the live oral cholera vaccine CVD 103-HgR induces a protective immune response in children and adolescents” ASTMH 2018; Abstract LB-5206.