A vaccine usually takes several years or even more than ten years from research and development to promotion. The research and development process has to go through three stages: experimental design, animal testing, and human clinical trial. Vaccines can only be produced in greater quantity and put into use after receiving the approval by the regulatory authority. Since the gene sequence of the novel coronavirus, SARS-Co-V-2, was announced in January 2020, a vaccine development competition began globally. More than 100 research and development projects around the world are approaching the clinical trial stage, Currently, there are 6 candidate vaccines that have entered clinical trial stages-3 in China, 2 in the United States, and 1 in the United Kingdom.

Three Vaccines in China Entered Clinical Trials

Recombinant novel coronavirus (adenovirus vector) vaccine, AD5-nCoV, is a cooperative project between the Hong Kong stock listed company (CanSino Biologics, China) and the Academy of Military Medical Sciences. The phase I clinical trial began on March 19, 2020. The phase II clinical trial currently in progress contains 500 participants.

Lentivirus vector modified dendritic cell vaccine (LV-SMENP-DC) and Lentivirus vector modified artificial antigen presenting cells (aAPC) with pathogen specificity, both of them are candidate vaccine developed by Shenzhen Geno-Immune Medical Institute.

These three candidate vaccines are all based on viral vector, are a more traditional type among the multiple technical platforms for the development of covid-19 vaccine. This kind of vaccines can provide high levels of protein expression, have long-term stability, and can induce a strong immune response. Once clinical trials are completed, it can almost directly start mass production.

Two Vaccines in USA Entered Clinical Trials

The first candidate vaccine for the SARS-CoV-2 in the United States MRNA-1273 project sponsored by the National Institutes of Health (NIH). It is based on mRNA (messenger ribonucleic acid) technology, designed and modified directly on the messenger ribonucleic acid, bypassing the novel coronavirus. It is different from the traditional vaccine development path. The vaccine development project has begun clinical trials on March 16, with 45 healthy adult men and women participating. It will end on June 1 and the result will be announced in the summer.

INO-4800 was designed by INOVIO Pharmaceuticals, Inc., in the San Diego laboratory. The SARS-CoV-2 vaccine was developed based on DNA (Deoxyribonucleic acid) drug platform. According to the “Los Angeles Times”, the company claimed to design the vaccine three hours after obtaining the viral gene sequence. The design strategy is to inject the DNA directly into human cells through a genetic plasmid, which generates antibodies to achieve immunity.

The two SARS-CoV-2 vaccines in the United States, which took the lead in entering clinical trials, adopt advanced gene modification and gene editing technology. This technology can quickly modify antigens as long as the viral gene sequences is known. It is said that Moderna’s mRNA-1273 vaccine took only 3 months from the publication of the covid-19 gene sequence to the start of the clinical trials, while the design of INO-4800 took only 3 hours.

One Vaccine in UK Entered Clinical Trials

Vacuna ChAdOx1 was the first vaccine in Europe and so far the only one to enter clinical trials, was jointly developed by the Jenner Institute, Oxford University and AstraZeneca. The clinical trial started on April 23.

Vacuna ChAdOx1 vaccine is developed based on adenovirus vector vaccine and SARS-CoV-2 spike protein, it has been tested in clinical trials for its effectiveness of anti-infection and safety. Phase III clinical trial is scheduled to end this fall. If the research and development results prove to be effective, the vaccine can be available limitedly as early as the end of 2020, with production capacity fight for reaching tens of millions of doses.

Effective vaccine to be developed and to be approved for putting into use by the regulatory authorities, which still faces various challenges and is affected by various factors, including different races, ages, social environments, and the individual's possible different response to the vaccine. Moreover, individuals may have different responses to the vaccine. Therefore, the vaccine’s effectiveness, safety, and public acceptance will all require a long-term ordeal.

Extend Reading

Zhang J., 2020, Latest progress: Adenovirus vector vaccine for COVID-19 enters phase I / II clinical trials, Journal of Vaccine Research, 10(1): 8-10

doi: 10.5376/jvr.2020.10.0002

Mason J., 2020, Public statement for collaboration on COVID-19 vaccine development by 120 experts worldwide, Journal of Vaccine Research, 10(1): 1-7

doi: 10.5376/jvr.2020.10.0001

Jessi Zhang is deputy director Institute of Life Science, Jiyang College of Zhejiang A&F University, Zhuji City, China. Jessi.j.zhang@cuixi.org