China’s CanSino Biologics Reports Promising Early Phase 2 COVID-19 Vaccine Data

CanSino Biologics Inc. (Tianjin, China) has announced promising Phase 2 results of its COVID-19 vaccine candidate which was shown to be safe and induced an immune response in a mid-stage clinical study.

CanSino’s recombinant novel coronavirus vaccine (Adenovirus Type 5 Vector) candidate (Ad5-nCoV), is built upon the company’s adenovirus-based viral vector vaccine technology platform, which has also been successfully applied to develop the globally innovative vaccine against Ebola virus infection. Results from preclinical animal studies of Ad5-nCoV have shown that the vaccine candidate can induce strong immune response in animal models. The preclinical animal safety studies also demonstrated a good safety profile. CanSino had moved forward the development of its COVID-19 vaccine candidate to Phase 2 after publishing data supporting its safety in patients in its Phase 1 trial.


In Phase 2, CanSino tested its vaccine, Ad5-nCOV, in 508 healthy adult subjects aged 18 years or older. Both the vaccine doses that were tested in the trial induced neutralizing antibody responses to SARS-CoV-2, with 85% of participants producing antibodies for the novel coronavirus and a T-cell response within 14 days of being dosed. The vaccine also appeared safe, although adverse reactions were reported by 72-74% of participants across both dosage groups. Nevertheless, serious adverse reactions were less common, with only 9% in the 1×1011 viral particles dose group and one participant in the 5×1010 viral particles dose group witnessing a serious side effect.

“With one dose, CanSino’s human adenovirus vector-based vaccine elicited receptor-binding and neutralizing antibodies in 508 patients peaking after 28 days. However, in the 52% of study participants that had a high pre-existing immunity to the viral vector, both types of antibodies were only at half the level than in the group with low-pre-existing immunity. A second dose of the vaccine might solve this issue, but on the other hand reduce the number of people who can be vaccinated,” said Philipp Rosenbaum, PhD, Senior Infectious Diseases Analyst at GlobalData, a leading data and analytics company.

“Nevertheless, the results are promising and warrant studies with more participants, longer observation of antibody levels and multiple vaccine doses – given the urgent need for a COVID-19 vaccine. Since CanSino is the first company to publish Phase 2 results, it has to been seen how the level of antibodies and T-cells will compare to results of COVID-19 vaccine candidates from other companies. However, it is still unclear which antibody levels will provide protection against SARS-CoV-2 and for how long this protection will last,” added Rosenbaum.

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