ISAAA News - May 27, 2020

New research published in The Lancet reports that the first COVID-19 vaccine to reach phase 1 clinical trial has been found to be safe, well-tolerated, and able to generate an immune response against SARS-CoV-2 in humans. The open-label trial in 108 healthy adults showed promising results after 28 days, while the final results will be evaluated in six months. Further trials are needed to tell whether the immune response that the vaccine elicits effectively protects against SARS-CoV-2 infection.

Between March 16 and March 27, 2020, 195 individuals were screened for their eligibility for the trials of an Ad5 vectored COVID-19 vaccine candidate in a rehabilitation center in Wuhan, Hubei province, China. Of these individuals, 108 participants (51% male, 49% female; mean age 36.3 years) were recruited and received the low dose (n=36), middle dose (n=36), or high dose (n=36) of the vaccine. Participants reported mild or moderate adverse reactions such as fever (50 [46%]), fatigue (47 [44%]), headache (42 [39%]), and muscle pain (18 [17%]). However, the research group pointed out that the severe adverse reactions were transient and self-limiting. Antibodies and neutralizing antibodies increased significantly at day 14, and peaked 28 days post-vaccination.

"These results represent an important milestone. The trial demonstrates that a single dose of the new adenovirus type 5 vectored COVID-19 (Ad5-nCoV) vaccine produces virus-specific antibodies and T cells in 14 days, making it a potential candidate for further investigation," says Professor Wei Chen from the Beijing Institute of Biotechnology in Beijing, China, who is responsible for the study.

For more details, read the online-first article in The Lancet.

Figure 2:  Flow cytometry with intracellular cytokine staining before and after vaccination