ZF2001
ZF2001, trade-named Zifivax or ZF-UZ-VAC-2001, is an adjuvanted protein subunit COVID-19 vaccine developed by Anhui Zhifei Longcom in collaboration with the Institute of Microbiology at the Chinese Academy of Sciences.[1][2] The vaccine candidate is in Phase III trials with 29,000 participants in China, Ecuador, Malaysia, Pakistan, and Uzbekistan.[3][4]
ZF2001 employs technology similar to other protein-based vaccines[5] in Phase III trials from Novavax, Vector Institute, and Medicago.[6]
ZF2001 was first approved for use in Uzbekistan and later China.[7][8] Production capacity is expected to be one billion doses a year in China[9] and 200 million in Uzbekistan.[10] By July, 100 million doses had been administered in China and Uzbekistan.[11]
Manufacturing[edit]
According to industry experts, production for this kind of vaccine is stable and reliable, and easier to achieve large-scale industrial production at home and overseas. However it was noted it can be very inconvenient for people to come back for a second and third dose.[9] Subunit vaccines are delivered alongside adjuvants and booster doses may be required.[15]
The company's vaccine manufacturing facility was put into use in September.[16] In February 2021, management said the company had an annual production capacity of 1 billion doses.[9]
In July 2021, an agreement was reached to produce the vaccine in Uzbekistan starting with 10 million doses a month and eventually 200 million doses a year.[10]
Research[edit]
As described in Cell, the CoV spike receptor-binding domain (RBD) is an attractive vaccine target for coronaviruses but is constrained by limited immunogenicity, however a dimeric form of MERS-CoV RBD offers greater protection. The RBD-dimer significantly increases neutralizing antibodies compared to a conventional monomeric form and protected mice against MERS-CoV infection. CoV RBD-dimer have been produced at high yields in pilot scale production.[34]
Rather than injecting a whole virus, subunit vaccines contains virus particles specially selected to stimulate an immune response. Because the fragments cannot cause disease, subunit vaccines are considered very safe.[15] Subunit vaccines in widespread use include the Hepatitis B vaccine and Pertussis vaccine. However, as only a few viral components are included in the vaccine which does not display the full complexity of the virus, their efficacy may be limited.[35]