FRIDAY, July 24, 2020 (HealthDay News) — A chimpanzee adenovirus-vectored vaccine (ChAdOx1 nCoV-19) expressing the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein has acceptable safety and induces antibody and T-cell immune responses, according to a study published online July 20 in The Lancet.

Pedro M. Folegatti, from the Jenner Institute at the University of Oxford in the United Kingdom, and colleagues conducted a phase 1/2, single-blind, randomized trial of a ChAdOx1 nCoV-19 compared to a meningococcal conjugate vaccine (MenACWY) as control. Healthy adults aged 18 to 55 years were randomly assigned to receive a single intramuscular injection of ChAdOx1 nCoV-19 at 5×1010 viral particles or MenACWY (543 and 534 participants, respectively); 10 participants were assigned to a ChAdOx1 nCoV-19 prime-boost group and received a two-dose schedule.

The researchers found that the ChAdOx1 nCoV-19 group more often had local and systemic reactions, many of which were reduced by prophylactic acetaminophen. ChAdOx1 nCoV-19 was not related to serious adverse events. Spike-specific T-cell responses peaked on day 14 in the ChAdOx1 nCoV-19 group. By day 28, anti-spike immunoglobulin G responses increased; these were boosted following a second dose. When measured by a microneutralization assay, neutralizing antibody responses against SARS-CoV-2 were detected in 91 percent of 35 participants after a single dose, while they were detected in 100 percent of 35 participants using a 50 percent plaque reduction neutralization assay. All participants had neutralizing activity after a booster dose.

“The preliminary results of this first-in-human clinical trial supported clinical development progression into ongoing phase 2 and 3 trials,” the authors write.

Several authors are named as inventors on a patent relating to ChAdOx1-vectored vaccines and this specific vaccine.

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