(HealthDay News) — A recombinant adenovirus type-5 (Ad5) vectored COVID-19 vaccine is safe, tolerable, and immunogenic, according to a study published online in The Lancet.

Feng-Cai Zhu, PhD, from the Jiangsu Provincial Center for Disease Control and Prevention in Nanjing, China, and colleagues conducted a dose-escalation, nonrandomized phase 1 trial of an Ad5 vectored COVID-19 vaccine in Wuhan, China. Healthy adults aged 18 to 60 years were enrolled and allocated to one of three dose groups to receive an intramuscular vaccine.

A total of 108 participants were recruited and received a low dose (5 × 1010 viral particles; 36 participants), middle dose (1 × 1011; 36 participants), or high dose (1.5 × 1011; 36 participants) of the vaccine. The researchers found that 83% 83% and 75% of participants in the low-, middle-, and high-dose vaccine groups, respectively, had at least 1 adverse reaction within the first 7 days after vaccination. The most common injection-site adverse reaction was pain, which was reported by 54% of vaccine recipients. Fever, fatigue, headache, and muscle pain were the most commonly reported systemic adverse reactions (46%, 44%, 39%, and 17%, respectively). In all dose groups, the adverse reactions were mostly mild or moderate in severity. There were no serious adverse events reported within 28 days after vaccination. At day 14, enzyme-linked immunosorbent assay antibodies and neutralizing antibodies increased significantly, peaking at 28 days after vaccination. At 14 days postvaccination, specific T-cell response peaked.

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“There is potential for further investigation of the Ad5 vectored COVID-19 vaccine for the control of the COVID-19 outbreak,” the authors write.

One author is an employee of CanSino Biologics, which partially funded the study.

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