Walvax COVID-19 vaccine

Vaccine description
Vaccine typemRNA
Clinical data
Routes of

ARCoV, also known as the Walvax COVID-19 vaccine, is an mRNA COVID-19 vaccine candidate developed by Walvax Biotechnology, Suzhou Abogen Biosciences, and the PLA Academy of Military Science.[1] In contrast to other mRNA covid vaccines developed by Pfizer-BioNtech, and Moderna, this vaccine primary aims at the Sars-Cov-2 RBD, rather than spike.[1] It is approved for Phase III trials in China,[2] Mexico,[3] Indonesia,[4] and Nepal.[5]


ARCoV is an mRNA vaccine which consists of lipid nanoparticle–encapsulated mRNA encoding the receptor binding domain of SARS-CoV-2. It was the first mRNA vaccine to be approved for clinical trials in China. Manufactured as a liquid, ARCoV is thermostable at room temperature for at least 1 week.[1] Reuters later reported that it can be stored at (2–8 °C) for six months.[3]

Scrips noted that Abogen created its own solid lipid nanoparticle to deliver the vaccine.[6]

In December, Walvax started constructing a facility to produce 120 million doses of the vaccine each year.[7] If successful, production of ARCoV could start in early 3rd quarter 2021.[8]

Clinical trials

Phase I and II trials

Preclinical studies in mice and primates have shown ARCoV elicited a Th1-biased cellular response and robust antibodies against SARS-CoV-2.[1][9]

In June 2020, Walvax began a Phase I trial to evaluate safety, tolerance, and preliminary immunogenicity with 168 participants aged 18–59 in Hangzhou divided into low-dose, medium-dose, and high-dose groups.[10]

In January 2021, Walvax began a Phase II trial to evaluate immunogenicity and safety of different doses with 420 participants aged 18–59 in Yongfu and Xiangfen divided into low-dose, medium-dose, high-dose, and placebo groups.[11]

In January 2022, the outcome of a Phase 1 study conducted in Shulan (Hangzhou, Zhejiang Province, China) was published in The Lancet. The vaccine doses trialed were 5, 10, 15, 20, 25 μg, and placebo. The trial measured anti-SARS-CoV-2 RBD IgG using a standardised ELISA, and neutralising antibodies using pseudovirus-based and live SARS-CoV-2 neutralisation assays. IFN-γ and IL-2 production were also measured, so are side effects. It was determined that fever was the most common systemic adverse reaction, but most of the fever resolved within 2 days after vaccination. The 15 μg group induced the highest titre of neutralising antibodies, which was about twofold more than the antibody titre of convalescent patients with COVID-19. All doses were well tolerated. A surprising unsolicited adverse reaction was a low lymphocyte count in those receiving the vaccine. This occurred in the majority of vaccinated individuals regardless of the dose, whereas only 10% of the placebo group encountered such adverse reaction. The authors pointed out that the lymphocyte count recovered to normal after 4 days.[12]

Low lymphocyte count could be a significant adverse event, especially for individuals who are unknowingly infected with SARS-CoV-2 at the time of vaccination. It is well known that a SARS-CoV-2 infection induces a decreased lymphocyte count,[13] and those with a lower lymphocyte count following infection face a significantly worse prognostic.[14] Considering that those infected by the SARS-CoV-2 are already under the strain of a low lymphocyte count, it will be imperative to ensure that those being vaccinated in the future are not infected by the virus at the time of vaccination.

Phase III trials

The Phase III trials would enroll an estimated 28,000 participants. Elderly people over 60 years old are planned to comprise 25% of trial participants and randomly assigned into the study group and control group at a ratio of 1:1.[15]

In July 2021, Phase III trials started in Yunnan and Guangxi in China with 2,000 people. Those provinces had previously experienced occasional small outbreaks from imported cases.[2]

In August 2021, Phase III trials were approved in Mexico with 6,000 people.[4] Previously in 2020, Walvax had previously expressed an interest in making the vaccine in Mexico.[16]

In August 2021, Phase III trials were approved in Indonesia.[4]

In July 2021, Phase III trials were awaiting approval by Malaysia's National Pharmaceutical Regulatory Agency (NPRA).[17]

In August 2021, Phase III trials were approved in Nepal with 3,000 people in Dharan.[5]

Colombia, Pakistan, and Turkey are other countries being considered for further trials.[18]


  1. ^ a b c "SARS-CoV-2 mRNA vaccine". go.drugbank.com. Retrieved 10 April 2021.
  2. ^ a b "Domestic clinical trials planned for China's mRNA Covid-19 vaccine". South China Morning Post. 22 July 2021. Retrieved 23 July 2021.
  3. ^ a b "Mexico to start late-stage clinical trial for China's mRNA COVID-19 vaccine". Reuters. 11 May 2021. Retrieved 14 May 2021.
  4. ^ a b c "Indonesia, Mexico approve phase 3 trials of Chinese mRNA vaccine hopeful". South China Morning Post. 1 September 2021. Retrieved 1 September 2021.
  5. ^ a b "Nepal approves late-stage trials for Chinese mRNA vaccine candidate". Reuters. 27 August 2021. Retrieved 28 August 2021.{{cite web}}: CS1 maint: url-status (link)
  6. ^ Yang, Brian. "How A Small Chinese Biotech Is Taking On mRNA Vaccine Giants". Scrip.{{cite web}}: CS1 maint: url-status (link)
  7. ^ Liu R (21 December 2020). "China starts work on plant for mRNA-based COVID-19 vaccine candidate - media". Reuters. Retrieved 10 April 2021.
  8. ^ "China's first mRNA vaccine ready for final stage trials". South China Morning Post. 13 April 2021. Retrieved 13 April 2021.
  9. ^ Zhang NN, Li XF, Deng YQ, Zhao H, Huang YJ, Yang G, et al. (September 2020). "A Thermostable mRNA Vaccine against COVID-19". Cell. 182 (5): 1271–1283.e16. doi:10.1016/j.cell.2020.07.024. PMC 7377714. PMID 32795413.
  10. ^ "A Phase I clinical trial to evaluate the safety, tolerance and preliminary immunogenicity of different doses of a SARS-CoV-2 mRNA vaccine in population aged 18–59 years and 60 years and above". Chinese Clinical Trial Register. 24 June 2020. ChiCTR2000034112. Archived from the original on 11 October 2020. Retrieved 6 July 2020.
  11. ^ "A Phase II clinical trial to evaluate the immunogenicity and safety of different doses of a novel coronavirus pneumonia (COVID-19) mRNA vaccine in population aged 18-59 years". chictr.org.cn. Chinese Clinical Trial Registry. Retrieved 20 March 2020.
  12. ^ Chen, Gui-Ling; Li, Xiao-Feng; Dai, Xia-Hong; Li, Nan; Cheng, Meng-Li; Huang, Zhen; Shen, Jian; Ge, Yu-Hua; Shen, Zhen-Wei; Deng, Yong-Qiang; Yang, Shu-Yuan (24 January 2022). "Safety and immunogenicity of the SARS-CoV-2 ARCoV mRNA vaccine in Chinese adults: a randomised, double-blind, placebo-controlled, phase 1 trial". The Lancet Microbe. doi:10.1016/S2666-5247(21)00280-9. ISSN 2666-5247. PMC 8786321. PMID 35098177.
  13. ^ Deng, Zhifeng; Zhang, Minli; Zhu, Ting; Zhili, Niu; Liu, Zheming; Xiang, Rong; Zhang, Wei; Xu, Yu (September 2020). "Dynamic changes in peripheral blood lymphocyte subsets in adult patients with COVID-19". International Journal of Infectious Diseases. 98: 353–358. doi:10.1016/j.ijid.2020.07.003. ISSN 1201-9712. PMC 7334931. PMID 32634585.
  14. ^ Zhang, Hong-Jun; Qi, Gang-Qiang; Gu, Xing; Zhang, Xiao-Yan; Fang, Yan-Feng; Jiang, Hong; Zhao, Yan-Jun (16 July 2021). "Lymphocyte blood levels that remain low can predict the death of patients with COVID-19". Medicine. 100 (28): e26503. doi:10.1097/MD.0000000000026503. ISSN 0025-7974. PMC 8284734. PMID 34260527.
  15. ^ Walvax Biotechnology Co., Ltd. (13 April 2021). "A Global, Multi-center, Randomized, Double-blind, Placebo-controlled, Phase III Clinical Trial to Evaluate the Protective Efficacy, Safety, and Immunogenicity of a SARS-CoV-2 Messenger Ribonucleic Acid (mRNA) Vaccine Candidate in Population Aged 18 Years and Above". Abogen Biosciences Co., Ltd. {{cite journal}}: Cite journal requires |journal= (help)
  16. ^ Daniel FJ (12 August 2020). "Mexico to trial China, U.S. COVID-19 vaccines, may produce some". Reuters. Retrieved 10 April 2021.
  17. ^ Daim, Nuradzimmah; Yunus, Arfa (27 July 2021). "Dr Adham: Covid-19 vaccine development in recruitment phase | New Straits Times". NST Online. Retrieved 28 July 2021.
  18. ^ "Late-stage trial of Chinese mRNA Covid-19 vaccine to begin in Mexico". South China Morning Post. 12 May 2021. Retrieved 17 May 2021.

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