Anhui Zhifei Longcom COVID-19 vaccine

Extended version of the vaccine

Anhui Zhifei Longcom COVID-19 vaccine

Authorization

World Health Organization Emergency Use Listing Procedure

Not authorized.
Expression of interest under assessment [Last checked at WHO EUL official website on 13 January 2022].

European Commission (based upon the recommendation of the European Medicines Agency [EMA])
Not authorized.

China's National Medical Products Administration
Authorized on 17 March 2021 [China's National Medical Products Administration, 2021 ].
Conditional marketing authorization for individuals 18 years of age and over.

Regulatory Authorities of Regional Reference in the Americas

National Administration of Drugs, Foods and Medical Devices (ANMAT, Argentina)
Not authorized.

Brazilian Health Regulatory Agency (ANVISA, Brazil)
Not authorized.

Health Canada
Not authorized.

Public Health Institute (ISP, Chile)
Not authorized.

National Institute of Food and Drug Monitoring (INVIMA, Colombia)
Not authorized.

Center for the State Control of Drug Quality (CECMED, Cuba)
Not authorized.

U.S. Food and Drug Administration (FDA)
Not authorized.

Federal Commission for the Protection against Sanitary Risk (COFEPRIS, Mexico)
Not authorized.

Authorization in other jurisdictions in the Americas
Not authorized.

Authorization in other jurisdictions
Indonesia
Uzbekistan

The Emergency Use Authorization does not constitute marketing authorization in the country.

Manufacturing

Manufacturer
Anhui Zhifei Longcom Biopharmaceutical Co.Ltd.; China. Sponsor of the vaccine clinical trials and main manufacturer [Business Insider, 2021 ].

Other manufacturers
Not described.

General characteristics

The Anhui Zhifei Longcom COVID-19 vaccine is an adjuvanted protein subunit COVID-19 vaccine. The protein subunit vaccine targets the receptor-binding domain (RBD) for SARS-CoV-2 located at C-terminal domain of S1 subunit in S protein (between R319 to K537) [An Y, 2021 ].

The protein was engineered as a tandem-repeat dimeric RBD to increase immunogenicity. Compared to the traditional monomeric RBD, RBD-dimer enhances the SARS-CoV-2 neutralizing antibodies [Dai L, 2020 ].

RBD is considered an attractive coronavirus vaccine target, because it focuses in the antibody response to block the receptor binding, therefore, poses low potential for antibody-dependent enhancement risk [Dai L, 2020 ].

The construct of RBD-dimer is produced in clinical-grade Chinese hamster ovary (CHO) cell lines and then formulated with aluminum hydroxide as an adjuvant, resulting in the final vaccine product [An Y, 2021 ].

 

Dosage form and ingredients

The pharmaceutical form is a suspension for intramuscular injection that is provided in a monodose vial of 0.5 mL.

The vaccine contains the following ingredients:

Active ingredient
Recombinant SARS-CoV-2 RBD protein 25 μg

Excipients
Aluminum hydroxide adjuvant 0.25 mg
Sodium chloride
Disodium phosphate
L-Histidine

Risk considerations

Peptide-based vaccines have theoretical advantages over traditional whole-organism and other platforms. They allow the immune response to focus on the protective epitopes and to exclude non-relevant epitopes, including those reactogenic or allergenic, at the stage of vaccine design [Reche PA, 2014 ].

Dosing and schedule

Dose-finding studies

The NCV-Ⅰ-healthy phase 1 trial (50 participants) and the NCV-ⅠI-healthy phase 2 trial (900 participants) assessed two different doses (25 μg and 50 μg) in a two-dose or three-dose schedule. The highest SARS-CoV-2 neutralizing response was recorded in the 25 µg/three-dose group [Yang S, 2021 ].

There is no evidence yet about the effects of the coadministration of Anhui Zhifei Longcom COVID-19 vaccine with other vaccines included in routine vaccination programs.

Indications and contraindications

Indications

Anhui Zhifei Longcom COVID-19 vaccine is indicated in adult individuals from 18 to 59 years of age [Yang S, 2021 ].

Contraindications

The vaccine is contraindicated in individuals with a known history of a severe allergic reaction to any component of the vaccine (See the list of ingredients under 'General characteristics' in the extended version).

The second dose of the vaccine should NOT BE GIVEN to those who have experienced anaphylaxis to the first dose of Anhui Zhifei Longcom COVID-19 vaccine.

Precautions

Severe allergic reaction (e.g., anaphylaxis) to a previous dose of any vaccine (not including Anhui Zhifei Longcom COVID-19 vaccine).

Severe allergic reaction (e.g., anaphylaxis) to an injectable medication.

Vaccination should be postponed in individuals suffering from acute severe febrile illness, or acute infection.

The available data on Anhui Zhifei Longcom COVID-19 vaccine on pregnant women are insufficient to assess vaccine efficacy in pregnancy since no clinical trial evaluating vaccines to prevent COVID-19 has included pregnant women.

The available data on Anhui Zhifei Longcom COVID-19 vaccine on children are insufficient to assess vaccine efficacy since no clinical trial evaluating vaccines to prevent COVID-19 has included children.

As with other intramuscular injections, the vaccine should be given with caution in individuals with bleeding disorders or other conditions that increase the risk of bleeding, such as anticoagulant therapy, thrombocytopenia and hemophilia.

There should be a minimum interval of 14 days between the administration of this vaccine with any other vaccine in the immunization schedule, until data on co-administration with other vaccines are available.

Vaccination may be offered regardless of a person’s history of symptomatic or asymptomatic SARS-CoV-2 infection.

Although there are currently no medical contraindications to vaccinate a person with COVID-19, it is recommended to defer all vaccinations until complete recovery [PAHO, 2020 ].

Although there are currently no contraindications to vaccinate a person who has had contact with a COVID-19 case, it is recommended to defer vaccination until the quarantine has been completed (14 days after the last exposure) [PAHO, 2020 ].


Close observation for at least 30 minutes is recommended following vaccination.

Close observation for at least 30 minutes is recommended following vaccination.

Clinical studies - general characteristics

Randomized trials

NCV-Ⅰ-healthy is a phase 1 randomized trial (registered with the number NCT04466085 [Anhui Zhifei Longcom Biologic Pharmacy Co., Ltd., 2020 ]) sponsored by Anhui Zhifei Longcom Biopharmaceutical that is being conducted in China [Yang S, 2021 ]. It was first registered in June 2020 and has enrolled 50 healthy adults aged 18–59 years that received three doses of the vaccine (25 μg or 50 μg) or placebo intramuscularly, 30 days apart in a 2:2:1 ratio. It is expected to run until September 2021. The first report of outcome data published in a scientific journal was released in March 2021.

NCV-Ⅱ-healthy is a phase 2 randomized trial (registered with the number NCT04466085 [Anhui Zhifei Longcom Biologic Pharmacy Co., Ltd., 2020 ]) sponsored by Anhui Zhifei Longcom Biologic Pharmacy Co., Ltd. that is being conducted in China [Yang S, 2021 ]. It was first registered in July 2020 and has enrolled 900 healthy people aged 18 to 59 years that received the vaccine (25 μg or 50 μg) or placebo intramuscularly, 30 days apart, in either a two-dose schedule or a three-dose schedule in a 1:1:1:1:1:1 ratio. It is expected to run until December 2021. The first report of outcome data published in a scientific journal was released in March 2021.

 

Ongoing randomized trials

LKM-2020-NCV-GJ01 is an ongoing phase 3 randomized trial (registered with the number NCT04646590) sponsored by Anhui Zhifei Longcom Biologic Pharmacy Co., Ltd. that is being conducted in China [Anhui Zhifei Longcom Biologic Pharmacy Co., Ltd., 2020 ]. It was first registered in November 2020 and plans to enroll 29000 healthy adults 18 years and older that will receive 25 μg of the vaccine in a 0, 1 and 2 month immunization schedule. It is expected to run until April 2022.

Methods used to assess efficacy

There are no phase 3 randomized trials that have yet reported outcome data.

Methods used to evaluate safety

There are no phase 3 randomized trials that have yet reported outcome data.

Efficacy and effectiveness of the vaccine

Efficacy of preclinical studies on the vaccine

The immunogenicity of the vaccine was evaluated in mice and nonhuman primates [An Y, 2021 ].

To study the immunogenicity, groups of BALB/c mice were vaccinated with two doses of 10 µg of the vaccine, 21 days apart. Mice receiving placebo (adjuvant only) were used as negative control. Serum samples from mice were collected at different time points after vaccination to monitor the duration of antibody responses. The geometric mean titer was 256 on day 35, after the second dose, the mean titers remained high until the last sample was taken at 140 days, suggesting that the humoral responses induced by the vaccine would be durable in time [An Y, 2021 ].

Young rhesus macaques were immunized with two doses of 25 μg or 50 μg vaccine intramuscularly, 21 days apart. Macaques that received a placebo were used as controls. The results showed that both doses elicited high levels of serological RBD-binding IgG and SARS-CoV-2 neutralizing antibodies after one or two immunizations [An Y, 2021 ].

Efficacy of the vaccine in clinical trials

Main immunogenicity outcomes

Combined analysis of NCV-Ⅱ-healthy and NCV-Ⅰ-healthyphase 1/2 trials. Phase 1 trial enrolled 50 participants that were assigned to receive three doses of placebo (n=10), the 25 µg vaccine (n=20), or the 50 µg vaccine (n=20). The mean age of participants was 32.6 years. Phase 2 trial enrolled 900 participants that were assigned to receive different schemes of vaccination. One group of participants was assigned to receive two doses of placebo (n=150), 25 µg vaccine (n=150), or 50 µg vaccine (n=150). While, the second group was assigned to receive three doses of placebo (n=150), 25 µg vaccine (n=150), or 50 µg vaccine (n=150). The mean age of participants was 43.5 years [Yang S, 2021 ].

In the phase 1 trial, the main immunogenicity outcome was measured with the serological RBD-binding IgG titres with ELISA test to assess antibody responses. Results showed that seroconversion rates, at day 30 after the second dose, reached 93% (14 of 15 participants) in the 25 µg group and 94% (17 of 18 participants) in the 50 µg group. The SARS-CoV-2-neutralising GMTs were 14% (95% CI 8-24.6) in the 25 µg group and 11.4% (95% CI 6.6-19.8) in the 50 µg group at day 30 after the second dose, and increased to 94.5% (95% CI 49.3-181.3) in the 25 µg group and 117.8% (95% CI 64.6-214.9) in the 50 µg group at day 7 after the third dose [Yang S, 2021 ].

In the two-dose groups in phase 2 of the trial, on day 14 after the third dose, seroconversion rates were 0% (none of 140) in the placebo group, 99% (143 of 144) in the 25 µg group and 97% (139 of 143) in the 50 µg group. The neutralizing GMTs for SARS-CoV-2, 14 days after the second dose were 17.7% (95% CI: 13.6-23) in the 25 µg group and 14% (95% CI : 10.8-18.3) in the 50 µg group. While in the group that received all three doses, the neutralizing GMTs of SARS-CoV-2 14 days later were 102.5% (95% CI: 81.8-128.5) in the group of 25 µg and 69% (95% CI 53-90) in the 50 µg group [Yang S, 2021 ].


Contracting COVID-19

The risk of contracting any COVID-19 infection has not yet been reported, so it was not possible to estimate the effect for this outcome.

Contracting severe COVID-19

The risk of contracting any COVID-19 infection has not yet been reported, so it was not possible to estimate the effect for this outcome.


Efficacy and effectiveness of the vaccine in subgroups

Sex

Randomized trials

There are no phase 3 randomized trials that have yet reported outcome data.

The differential efficacy of the vaccine in sex groups was not reported in the NCV-Ⅰ-healthy phase 1 trial and the NCV-Ⅱ-healthy phase 2 trial [Yang S, 2021 ].

 
Age

Randomized trials

There are no phase 3 randomized trials that have yet reported outcome data.

The differential efficacy of the vaccine in different age groups was not reported in the NCV-Ⅰ-healthy phase 1 trial and the NCV-Ⅱ-healthy phase 2 trial [Yang S, 2021 ].

 
Children and adolescents

Randomized trials

There are no phase 3 randomized trials that have yet reported outcome data.

Children and adolescents were excluded from the NCV-Ⅰ-healthy phase 1 trial and the NCV-Ⅱ-healthy phase 2 trial, so no data are available for this subgroup [Yang S, 2021 ].

 
Pregnancy

Randomized trials

There are no phase 3 randomized trials that have yet reported outcome data.

Pregnant females were excluded from the NCV-Ⅰ-healthy phase 1 trial and the NCV-Ⅱ-healthy phase 2 trial, so no data are available for this subgroup [Yang S, 2021 ].

 
Breast-feeding

Randomized trials

There are no phase 3 randomized trials that have yet reported outcome data.

Breastfeeding females were excluded from the NCV-Ⅰ-healthy phase 1 trial and the NCV-Ⅱ-healthy phase 2 trial, so no data are available for this subgroup [Yang S, 2021 ].

 
Immunocompromised persons

Randomized trials

There are no phase 3 randomized trials that have yet reported outcome data.

Immunocompromised participants were excluded from the NCV-Ⅰ-healthy phase 1 trial and the NCV-Ⅱ-healthy phase 2 trial, so no data are available for this subgroup [Yang S, 2021 ].

Other data on vaccine efficacy and effectiveness

Main effectiveness outcomes of Anhui Zhifei Longcom COVID-19 vaccine (Other studies)

Contracting COVID-19

No studies reported or assessed this outcome.

Contracting severe COVID-19

No studies reported or assessed this outcome.

Transmission

No studies reported or assessed this outcome.

SARS-CoV-2 variants

Immunogenicity outcomes

Zhao X et al. carried out a non-comparative study (neutralizing capacity from recipients' sera) in China, which included 28 vaccine recipients. The study reported data from the participants' serum samples. The results showed that the neutralizing titer did not decline, but slightly increased (1.1 fold to WT, P > 0.05), against B.1.1.7-spike pseudovirus. [Xin Zhao, 2021 ].

Huang B et al. conducted a comparative study (neutralizing capacity from recipients' sera) in China, which included 12 vaccine recipients. The study reported data from the participants' serum samples. The results showed that Beta variant does not escape the immunity induced by vaccine targeting S protein dimeric RBD (Anhui Zhifei Longcom). GMT decreased from 106.1 (95% CI 75.0 to 150.1) to 66.6 (95% CI 51.0 to 86.9) [Huang B, 2021 ].

Cao Y et al. conducted a comparative study (neutralizing capacity from recipients' sera) in China, which included 20 Anhui Zhifei Longcom vaccine volunteers. The study reported data from the participants' serum samples. Results demonstrated that individuals are capable of inducing highly diverse anti-RBD NAbs that react differently toward the B.1.351 variant. These enable Anhui Zhifei Longcom vaccinees to exhibit a two times higher tolerance to 501Y.V2 variants [Cao Y, 2021 ].

Zhao X et al. carried out a non-comparative study (neutralizing capacity from recipients' sera) in China, which included 28 vaccine recipients. The study reported data from the participants' serum samples. The results showed that the variant with double mutations in RBD B.1.617.2 [Delta]-spike showed roughly equivalent sensitivity to ZF2001-elicited antisera as compared with pseudovirus expressing WTspike (-1.1 and -1.2 fold to WT, respectively; p > 0.05) [Xin Zhao, 2021 ].

Randomized trials

Currently, there are no studies that have assessed the vaccine efficacy outcomes against SARS-CoV-2 Variants.

Other studies

Currently, there are no studies that have assessed the vaccine efficacy outcomes against SARS-CoV-2 Variants.

 

Booster dose

Immunogenicity outcomes

Currently, there are no studies that have assessed the vaccine immunogenicity outcomes on a booster regimen.

Heterologous vaccine regimens

Immunogenicity outcomes

Currently, there are no studies that have assessed the vaccine immunogenicity outcomes on heterologous regimen.


Heterologous-booster regimens

Immunogenicity outcomes

Currently, there are no studies that have assessed the vaccine immunogenicity outcomes on a heterologous-booster regimen.

Safety of the vaccine

Safety of the vaccine in preclinical studies

Safety outcomes were not assessed in the animal studies available [An Y, 2021 ].

Safety of the vaccine in clinical trials

Any adverse event

The combined analysis of NCV-Ⅱ-healthy and NCV-Ⅰ-healthy, the most common solicited systemic adverse events were cough, fever, and headache. Two (10%) grade 3 adverse events were reported in the 50 µg group. In the phase 2 trial, the overall frequency of adverse events after 30 days of vaccination, among participants receiving two doses, was 37 (25%) of 150 participants in the placebo group, 43 (29%) of 150 participants in the 25 µg group, and 50 (33%) of 150 participants in the 50 µg group. Participants receiving three doses, 47 (31%) of 150 in the placebo group, 72 (48%) of 150 in the 25 µg group, and 65 (43%) of 150 in the 50 µg group reported at least one adverse event. The most common solicited local adverse events in participants on the two-dose and three-dose schedules were injection-site pain, swelling, induration, redness, and itch. The most common solicited systemic adverse events in participants on the two-dose and three-dose schedules were fever, cough, headaches, and fatigue [Yang S, 2021 ].

Serious adverse events

There are no phase 3 randomized trials that have yet reported outcome data.

In the phase 1/2 trial combined analysis of NCV-Ⅱ-healthy and NCV-Ⅰ-healthy, serious adverse events were not observed [Yang S, 2021 ].


Non-serious adverse events

There are no phase 3 randomized trials that have yet reported outcome data.

In the phase 1/2 trial combined analysis of NCV-Ⅱ-healthy and NCV-Ⅰ-healthy, non-serious adverse events were not observed [Yang S, 2021 ].

Safety of the vaccine in subgroups

Sex

Randomized trials

There are no phase 3 randomized trials that have yet reported outcome data.

The differential safety of the vaccine in sex groups was not reported in the NCV-Ⅰ-healthy phase 1 trial and the NCV-Ⅱ-healthy phase 2 trial [Yang S, 2021 ].

 

Age

Randomized trials

There are no phase 3 randomized trials that have yet reported outcome data.

The differential safety of the vaccine across age groups was not reported in the NCV-Ⅰ-healthy phase 1 trial and the NCV-Ⅱ-healthy phase 2 trial [Yang S, 2021 ].

 
Children and adolescents

Randomized trials

There are no phase 3 randomized trials that have yet reported outcome data.

Children and adolescents were excluded from the NCV-Ⅰ-healthy phase 1 trial and the NCV-Ⅱ-healthy phase 2 trial, so no data are available for this subgroup [Yang S, 2021 ].

 
Pregnancy

Randomized trials

There are no phase 3 randomized trials that have yet reported outcome data.

Pregnant females were excluded from the NCV-Ⅰ-healthy phase 1 trial and the NCV-Ⅱ-healthy phase 2 trial, so no data are available for this subgroup [Yang S, 2021 ].

 
Breast-feeding

Randomized trials

There are no phase 3 randomized trials that have yet reported outcome data.

Breastfeeding females were excluded from the NCV-Ⅰ-healthy phase 1 trial and the NCV-Ⅱ-healthy phase 2 trial, so no data are available for this subgroup [Yang S, 2021 ].

 
Immunocompromised persons

Randomized trials

There are no phase 3 randomized trials that have yet reported outcome data.

Immunocompromised participants were excluded from the NCV-Ⅰ-healthy phase 1 trial and the NCV-Ⅱ-healthy phase 2 trial, so no data are available for this subgroup [Yang S, 2021 ].

Safety of the vaccine post-authorization

Post-authorization studies

Comparative studies

None available

Non-comparative studies

None available.

 

Monitoring

WHO recommends the following research and post-authorization monitoring activities:

Safety surveillance and monitoring
- Serious adverse events, anaphylaxis and other serious allergic reactions, Bell’s palsy, cases of multisystem inflammatory syndrome following vaccination, cases of COVID-19 following vaccination that result in hospitalization or death.

Vaccine effectiveness
− Vaccine effectiveness over time and whether protection can be prolonged by booster doses.
− Studies to investigate whether this vaccine reduces SARS-CoV-2 transmission and viral shedding.
− Assessment and reporting of vaccination failures and virus sequence information.

Subgroups
− Prospective studies on the safety of COVID-19 vaccine in pregnant and lactating females.
− Randomized controlled trials on efficacy and safety of vaccination in children below the age of 18 years.
− Safety data on vaccination in immunocompromised people, including patients living with HIV and autoimmune disease.

Vaccination logistics
− Immunogenicity and safety studies of co-administration with other vaccines, including influenza and pneumococcal vaccines, to adults and older persons.
− Safety, immunogenicity, and impact of a delayed second dose, as currently implemented by certain countries.
− Stability of the vaccine under alternative cold-chain distribution and storage conditions.
− Effectiveness of the proposed strategies for the prevention and management of anaphylactic reactions.
− Interchangeability studies within and across COVID-19 vaccine platforms.

References

[China's National Medical Products Administration, 2021] China's National Medical Products Administration. China approves new type of vaccine for emergency use against COVID-19. Press release - China Daily - 2021-03-17. 2021; China's National Medical Products Administration. China approves new type of vaccine for emergency use against COVID-19. Press release - China Daily - 2021-03-17. 2021;
[Business Insider, 2021] Business Insider. Another Chinese Covid-19 vaccine enters late-stage human trials with a plan to produce 300 million doses annually. News. 2021; Business Insider. Another Chinese Covid-19 vaccine enters late-stage human trials with a plan to produce 300 million doses annually. News. 2021;
[An Y, 2021] An Y, Li S, Jin X et al. A tandem-repeat dimeric RBD protein-based COVID-19 vaccine ZF2001 protects mice and nonhuman primates. bioRxiv. 2021; An Y, Li S, Jin X et al. A tandem-repeat dimeric RBD protein-based COVID-19 vaccine ZF2001 protects mice and nonhuman primates. bioRxiv. 2021;
[Dai L, 2020] Dai L, Zheng T, Xu K et al. A Universal Design of Betacoronavirus Vaccines against COVID-19, MERS, and SARS. Cell. 2020;182(3). Dai L, Zheng T, Xu K et al. A Universal Design of Betacoronavirus Vaccines against COVID-19, MERS, and SARS. Cell. 2020;182(3).
[Reche PA, 2014] Reche PA, Fernandez-Caldas E, Flower DR, Fridkis-Hareli M, Hoshino Y. Peptide-based immunotherapeutics and vaccines. Journal of immunology research. 2014;2014:256784. Reche PA, Fernandez-Caldas E, Flower DR, Fridkis-Hareli M, Hoshino Y. Peptide-based immunotherapeutics and vaccines. Journal of immunology research. 2014;2014:256784.
[Yang S, 2021] Yang S, Li Y, Dai L et al. Safety and immunogenicity of a recombinant tandem-repeat dimeric RBD-based protein subunit vaccine (ZF2001) against COVID-19 in adults: two randomised, double-blind, placebo-controlled, phase 1 and 2 trials. The Lancet. Infectio Yang S, Li Y, Dai L et al. Safety and immunogenicity of a recombinant tandem-repeat dimeric RBD-based protein subunit vaccine (ZF2001) against COVID-19 in adults: two randomised, double-blind, placebo-controlled, phase 1 and 2 trials. The Lancet. Infectio
[PAHO, 2020] PAHO. The Immunization Program in the Context of the COVID-19 Pandemic, 26 March 2020. PAHO/FPL/IM/COVID-19/20-0005. 2020; PAHO. The Immunization Program in the Context of the COVID-19 Pandemic, 26 March 2020. PAHO/FPL/IM/COVID-19/20-0005. 2020;
[Anhui Zhifei Longcom Biologic Pharmacy Co., Ltd., 2020] Anhui Zhifei Longcom Biologic Pharmacy Co., Ltd.. Phase I Clinical Study of Recombinant Novel Coronavirus Vaccine (CHO Cells). clinicaltrials.gov. 2020; Anhui Zhifei Longcom Biologic Pharmacy Co., Ltd.. Phase I Clinical Study of Recombinant Novel Coronavirus Vaccine (CHO Cells). clinicaltrials.gov. 2020;
[Anhui Zhifei Longcom Biologic Pharmacy Co., Ltd., 2020] Anhui Zhifei Longcom Biologic Pharmacy Co., Ltd.. Clinical Study of Recombinant Novel Coronavirus Vaccine. clinicaltrials.gov. 2020; Anhui Zhifei Longcom Biologic Pharmacy Co., Ltd.. Clinical Study of Recombinant Novel Coronavirus Vaccine. clinicaltrials.gov. 2020;
[Anhui Zhifei Longcom Biologic Pharmacy Co., Ltd., 2020] Anhui Zhifei Longcom Biologic Pharmacy Co., Ltd.. A Phase III Clinical Trial to Determine the Safety and Efficacy of ZF2001 for Prevention of COVID-19. clinicaltrials.gov. 2020; Anhui Zhifei Longcom Biologic Pharmacy Co., Ltd.. A Phase III Clinical Trial to Determine the Safety and Efficacy of ZF2001 for Prevention of COVID-19. clinicaltrials.gov. 2020;
[Xin Zhao, 2021] Xin Zhao, Anqi Zheng, Dedong Li et al. Neutralization of recombinant RBD-subunit vaccine ZF2001-elicited antisera to SARS-CoV-2 variants including Delta. bioRxiv. 2021; Xin Zhao, Anqi Zheng, Dedong Li et al. Neutralization of recombinant RBD-subunit vaccine ZF2001-elicited antisera to SARS-CoV-2 variants including Delta. bioRxiv. 2021;
[Huang B, 2021] Huang B, Dai L, Wang H et al. Serum sample neutralisation of BBIBP-CorV and ZF2001 vaccines to SARS-CoV-2 501Y.V2. The Lancet. Microbe. 2021; Huang B, Dai L, Wang H et al. Serum sample neutralisation of BBIBP-CorV and ZF2001 vaccines to SARS-CoV-2 501Y.V2. The Lancet. Microbe. 2021;
[Cao Y, 2021] Cao Y, Yisimayi A, Bai Y et al. Humoral immune response to circulating SARS-CoV-2 variants elicited by inactivated and RBD-subunit vaccines. Cell research. 2021;31(7):732-741. Cao Y, Yisimayi A, Bai Y et al. Humoral immune response to circulating SARS-CoV-2 variants elicited by inactivated and RBD-subunit vaccines. Cell research. 2021;31(7):732-741.
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