COVID-19: China approves vaccine for use by military only without phase III study

Today China approved a Covid-19 vaccine, for use only by its military. Importantly, however, this approval occurred despite the vaccine not having undergone a phase III efficacy study.

As reported by Josephine Ma in the South China Morning Post, this vaccine was developed by the company CanSino Biologics (Tianjin) and a research institute at the Academy of Military Science that is headed by Major General Chen Wei. The vaccine cannot be given to civilians at this time.

The vaccine is termed “Ad5 vectored Covid-19 vaccine”. It combines a recombinant adenovirus type-5 vectored spike glycoprotein of the SARS-CoV-2 virus. The phase I vaccine was the first (or among the first) to be published in a peer review journal. Although at least one phase II study (NCT04341389) has taken place, it has not yet been published.

The phase I trial took place in Wuhan. Published online May 22, in The Lancet, it was titled: "Safety, tolerability, and immunogenicity of a recombinant adenovirus type-5 vectored COVID-19 vaccine: a dose-escalation, open-label, non-randomized, first-in-human trial."

In this phase I study, a single dose was given to 108 volunteers who were between ages 18 and 60, with  36 persons receiving the low-dose, 36 the middle-dose, and 36 the high dose of the vaccine. Both T-cell and antibody (B-cell) responses were measured. The authors noted that in the high dose group “severe fever, fatigue, dyspnea, muscle pain, and joint pain were reported in some of the recipients”.

They also noted other potential concerns: ”However, aside from pre-existing anti-Ad5 immunity, there is concern about the increased risk of HIV-1 acquisition associated with Ad5 activated CD4 T-cells. Although the association between HIV-1 acquisition risk and Ad5 vectored vaccine is controversial and its mechanism is unclear, the potential risks should be taken into account in studies with this viral vector delivery platform.” (The authors referenced a phase 2 HIV vaccine study in South Africa that also used a recombinant adenovirus type 5 published by Gray G. et al in The Lancet Infectious Diseases 2014; 14: 388-396).

On the website of CanSinoBIO, it is reported that they had also worked with the Academy of Military Medical Sciences to develop and receive approval for an Adenovirus 5 vectored vaccine against Ebola.