On Feb. 25, the National Medical Products Administration of China (NMPA) conditionally approved the registration applications of two COVID-19 vaccines: Inactivated COVID-19 Vaccine (Vero Cell) of Sinopharm Wuhan Institute of Biological Products Co., Ltd., and Recombinant Novel Coronavirus Vaccine (Adenovirus Type 5 Vector) of CanSinoBIO, with the latter being the first Chinese-produced adenovirus vector-based COVID-19 vaccine approved.
The marketing registration applications of four Chinese-produced COVID-19 vaccines have so far received the NMPA’s conditional approval. In addition to the two mentioned above, the other two vaccines are the Inactivated COVID-19 Vaccine (Vero Cell) of Sinopharm Beijing Institute of Biological Products Co., Ltd. approved on Dec. 30, 2020, and the SARS-CoV-2 Vaccine (Vero Cell), Inactivated of Sinovac Life Sciences Co., Ltd. approved on Feb. 5, 2021. With real-world protection efficacy data reported in succession after vaccination, humanity is expected to usher in a new situation in the fight against the pandemic. These healthcare supply companies have made great contribution to the vaccination. COVID-19 vaccine R&D in China has also made new progress in succession. Let’s check it.
1. Sinopharm CNBG: The first inactivated COVID-19 vaccine approved for marketing in China
The inactivated COVID-19 vaccine from Sinopharm CNBG was conditionally approved by the NMPA at the end of Dec. 2020, making it the first inactivated COVID-19 vaccine approved for marketing in China. To put it simply, to make inactivated vaccines, the virus strains are first isolated, just like choosing good “seeds”; then they are cultured, for example, multiplying tens or hundreds of times; the live viruses are then killed so that they lose their infectivity and replication ability but retain part of their function of stimulating the human body to produce an immune response, and then they are finally turned into vaccines through purification and other processes. Inactivated vaccines are relatively faster to develop, but the required investment is huge.
The Lancet, an international academic medical journal, published the results of the Phase 1/2 clinical trial of the vaccine on Oct. 16, 2020. This randomized, double-blind, placebo-controlled, phase 1/2 trial divided 192 healthy adults into groups aged 18-59 and ≥60 to evaluate low, medium, and high doses of the vaccine. Participants in each group were randomly assigned 3:1 to separately receive the vaccine or the placebo. In phase 2, 448 healthy adults (aged 18-59) were assigned to four groups to receive the high-dose vaccine on day 0 or the medium-dose vaccine on days 0/14, 0/21, or 0/28 to mainly assess safety and tolerability, with the secondary outcome being immunogenicity, assessed as the neutralizing antibody responses against infectious SARS-CoV-2.
According to the results of the study on candidate vaccine-induced neutralizing antibodies and positive conversion rates, in phase 1 clinical trial, in the healthy adult group, seroconversion rates reached 100% at day 14 in both the low and medium dose populations and 96% at day 14 in the high dose population; in the elderly group, seroconversion rates reached 100% at day 28 for all populations; in all groups, neutralizing antibodies increased significantly from day 7 and peaked at day 42. Vaccine-induced neutralizing antibody titers in the high-dose group were significantly higher than those in the low-dose group, but not significantly different from those in the medium-dose group. Furthermore, the vaccine-induced neutralizing antibodies neutralized various viral strains, including the natural variant with spike mutant (D614G) in the current pandemic. According to phase 2 clinical results, neutralizing antibodies increased from day 14 to day 28 after the second vaccination in the D0/D14 and D0/D21 procedures; vaccine-induced neutralizing antibody ti...
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