Adenovirus Type-5 Vectored COVID-19 Vaccine Shows Promise

ELISA antibodies and neutralizing antibodies increased at day 14, peaked at day 28

man getting vaccine

TUESDAY, May 26, 2020 (HealthDay News) -- A recombinant adenovirus type-5 (Ad5) vectored COVID-19 vaccine is safe, tolerable, and immunogenic, according to a study published online May 22 in The Lancet.

Feng-Cai Zhu, Ph.D., 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 percent of participants in the low-, middle-, and high-dose vaccine groups, respectively, had at least one adverse reaction within the first seven days after vaccination. The most common injection-site adverse reaction was pain, which was reported by 54 percent of vaccine recipients. Fever, fatigue, headache, and muscle pain were the most commonly reported systemic adverse reactions (46, 44, 39, and 17 percent, 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.

"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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