COVID-19Phase 3NCT05542862

Booster Study of SpikoGen COVID-19 Vaccine

A Phase 3 study testing SpikoGen vaccine in people with COVID-19, run by Vaxine Pty Ltd at 1 site in Australia.

Completed

Finished. The study has ended and is not enrolling. Results may be posted on the official record.

Trial summary

The purpose of the study is to assess the effectiveness of Spikogen vaccine when used as a 3rd or 4th dose booster in adults who have been previously vaccinated with any Covid-19 vaccine types, including mRNA vaccine, adenoviral vector vaccines, recombinant protein vaccines, or inactivated virus vaccines. Read more about this study

Who is it for?: Ages 18 years and olderHealthy volunteers can take part
Conditions the study is for: COVID-19
What is being tested?: SpikoGen vaccine
Type of treatment: Vaccines
Could I receive a placebo?: No, everyone receives an active treatment
How many people: 81 participants
Where: 1 siteAustralia
Study dates: 7 Sep 2022to 16 Sep 2025
Phase: Phase 3
Are there results?: None posted in the registry

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

Ages 18 years and older
All sexes
Healthy volunteers accepted
Adult, Older adult

Who may be able to join

Able to provide written informed consent
Males or females 18 years of age or older
Have previously had a primary course of Covid-19 vaccine with the most recent dose no less than 3 months previously.
Understand and are likely to comply with planned study procedures and be available for all study visits.

Who cannot join

Allergy to Spikogen vaccine or one of its components, e.g. polysorbate 80.
Have received an experimental agent within 30 days prior to the study vaccination or expect to receive another experimental agent during the trial reporting period.
Any serious medical, social or mental condition which, in the opinion of the investigator, would be detrimental to the subjects or the study.

Trial locations and contacts

1 site in 1 country.

Australia1 site

ARASMI
Adelaide, South Australia, 5042

Other trials in Australia

About this study

Official title: Immunogenicity and Safety Study in Ambulatory Adults of a Single Intramuscular Dose of SpikoGen Vaccine as a Heterologous or Homologous Booster Dose Following Completion of a Primary Course of Covid-19 Vaccine

Read the detailed description

Currently in Australia, mRNA, adenoviral vector and recombinant protein vaccines have provisional approval for use as 3rd or 4th booster doses. This study will provide important data on the use of Spikogen as an alternative recombinant protein booster vaccine. The study will provide data in ambulatory adults on the safety and effectiveness of Spikogen vaccine when administered as a single intramuscular booster dose in those who previously vaccinated with mRNA vaccine in comparison to those immunised with other Covid-19 vaccine platforms.

Conditions: COVID-19
Being tested: SpikoGen vaccine
Keywords: covid-19, vaccine, adjuvant, Spikogen, Advax, CpG55.2
Medical subject headings: COVID-19

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

SpikoGen vaccineBiological
Also called Covax-19
Recombinant spike protein based Covid-19 vaccine

Study groups in NCT05542862
Study group	Role	What they receive
SpikoGen vaccine	Experimental	Single booster dose of SpikoGen Covid-19 vaccine Receives: Biological: SpikoGen vaccine

What is being measured

The primary outcome is the main question the study is designed to answer.

Seroconversion
Proportion of study participants who seroconvert (4-fold or greater rise in serum spike antibody) by primary vaccine group
Measured: Between baseline and 4 weeks post the booster dose
Seroprotection
Proportion of study participants who achieve a spike protein neutralisation titer of 32 or greater by primary vaccine group
Measured: Between baseline and 4 weeks post the booster dose
Geometric mean titer fold change
Increase in Geometric mean titer of spike neutralisation antibodies by primary vaccine group
Measured: Between baseline and 4 weeks post the booster dose
Safety assessment 1
Frequency of Adverse events by primary vaccine group
Measured: Occurring within 7 days after booster dose.
Safety assessment 2
Frequency of Serious Adverse events by primary vaccine group
Measured: Between time of administration of booster dose and through study completion, an average of 3 months
SARS-CoV-2 infection
Frequency of SARS-CoV-2 infections in study participants by primary vaccine group, age, gender, co-morbidities, and past infection
Measured: Between time of administration of booster dose and through study completion, an average of 3 months
Antibody durability
The proportion of subjects who remain seroprotected throughout the duration of the study including broken down by primary vaccine group.
Measured: Between time of administration of booster dose and through study completion, an average of 3 months
Seroconversion in participants with and without evidence of past infection
Spike antibody seroconversion in baseline nuclear protein antibody positive versus negative participants by primary vaccine group
Measured: Between baseline and 4 weeks post the booster dose and through study completion, an average of 3 months
Seroprotection in participants with and without evidence of past infection
Spike antibody seroprotection in baseline nuclear protein antibody positive versus negative participants by primary vaccine group
Measured: Between baseline and 4 weeks post the booster dose and through study completion, an average of 3 months
Spike antibody GMT in participants with and without evidence of past infection
Spike antibody GMT in baseline nuclear protein antibody positive versus negative participants by primary vaccine group.
Measured: Between baseline and 4 weeks post the booster dose and through study completion, an average of 3 months

Secondary outcomes (1)

Antibody correlates of protection
SARS-CoV-2 antibody levels in subjects with or without breakthrough SARS-CoV-2 infection
Measured: Baseline and 4 weeks post the booster dose, and through study completion, an average of 3 months

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

7 Sep 202216 Sep 2025

First posted16 Sep 2022
Study start7 Sep 2022
Primary completion31 Dec 2023
Study completion16 Sep 2025

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Publications (6)Papers the sponsor has linked to this study.
Other trials for COVID-19Studies of the same condition, open and under way.
What the trial phases meanHow a treatment moves from first tests in people to approval.

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design

Study type: Interventional
Phase: Phase 3
Primary purpose: Prevention
Allocation: Not applicable
Intervention model: Single group
Model description: All subjects will receive the same single intervention with analysis groups being based on the type of primary vaccine received
Masking: None (open label)
Enrolment: 81 participants (actual)

IDs, dates and publications

ClinicalTrials.gov ID: NCT05542862
Sponsor's protocol ID: AUST-C19-booster
Status last verified: Sep 2025
First submitted: 8 Sep 2022
Last updated: 17 Sep 2025
Results posted: No
Data monitoring committee: Yes
FDA-regulated drug: No
FDA-regulated device: No
Individual data sharing: No

Publications

Tabarsi P, Anjidani N, Shahpari R, Mardani M, Sabzvari A, Yazdani B, Roshanzamir K, Bayatani B, Taheri A, Petrovsky N, Li L, Barati S. Safety and immunogenicity of SpikoGen(R), an Advax-CpG55.2-adjuvanted SARS-CoV-2 spike protein vaccine: a phase 2 randomized placebo-controlled trial in both seropositive and seronegative populations. Clin Microbiol Infect. 2022 Sep;28(9):1263-1271. doi: 10.1016/j.cmi.2022.04.004. Epub 2022 Apr 15.
PubMed 35436611
Tabarsi P, Anjidani N, Shahpari R, Roshanzamir K, Fallah N, Andre G, Petrovsky N, Barati S. Immunogenicity and safety of SpikoGen(R), an adjuvanted recombinant SARS-CoV-2 spike protein vaccine as a homologous and heterologous booster vaccination: A randomized placebo-controlled trial. Immunology. 2022 Nov;167(3):340-353. doi: 10.1111/imm.13540. Epub 2022 Jul 13.
PubMed 35758850
Li L, Honda-Okubo Y, Baldwin J, Bowen R, Bielefeldt-Ohmann H, Petrovsky N. Covax-19/Spikogen(R) vaccine based on recombinant spike protein extracellular domain with Advax-CpG55.2 adjuvant provides single dose protection against SARS-CoV-2 infection in hamsters. Vaccine. 2022 May 20;40(23):3182-3192. doi: 10.1016/j.vaccine.2022.04.041. Epub 2022 Apr 18.
PubMed 35465982
Li L, Honda-Okubo Y, Huang Y, Jang H, Carlock MA, Baldwin J, Piplani S, Bebin-Blackwell AG, Forgacs D, Sakamoto K, Stella A, Turville S, Chataway T, Colella A, Triccas J, Ross TM, Petrovsky N. Immunisation of ferrets and mice with recombinant SARS-CoV-2 spike protein formulated with Advax-SM adjuvant protects against COVID-19 infection. Vaccine. 2021 Sep 24;39(40):5940-5953. doi: 10.1016/j.vaccine.2021.07.087. Epub 2021 Aug 3.
PubMed 34420786
Tabarsi P, Anjidani N, Shahpari R, Mardani M, Sabzvari A, Yazdani B, Kafi H, Fallah N, Ebrahimi A, Taheri A, Petrovsky N, Barati S. Evaluating the efficacy and safety of SpikoGen(R), an Advax-CpG55.2-adjuvanted severe acute respiratory syndrome coronavirus 2 spike protein vaccine: a phase 3 randomized placebo-controlled trial. Clin Microbiol Infect. 2023 Feb;29(2):215-220. doi: 10.1016/j.cmi.2022.09.001. Epub 2022 Sep 10.
PubMed 36096430
Honda-Okubo Y, Sajkov D, Wauchope B, Turner JV, Vote B, Antipov A, Andre G, Lebedin Y, Petrovsky N. Immunogenicity and safety study of a single dose of SpikoGen(R) vaccine as a heterologous or homologous intramuscular booster following a primary course of mRNA, adenoviral vector or recombinant protein COVID-19 vaccine in ambulatory adults. Vaccine. 2025 Mar 7;49:126744. doi: 10.1016/j.vaccine.2025.126744. Epub 2025 Feb 5.
PubMed 39914274

Want to know more?

The sponsor has not listed a contact. The official record may have more details.

Talk to your doctor first and take this page with you. Only the study team can confirm whether you can join.

Questions to ask the study team

What is the study trying to find out?
What would I need to do, and how often would I visit?
Could I receive a placebo instead of the treatment?
What are the possible risks and benefits for me?
Will it cost me anything? Are travel or time paid for?
Can I keep seeing my own doctor during the study?
What happens when the study ends?

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All COVID-19 trials

Study at a glance

From the registry record, last updated by the sponsor on 17 Sep 2025. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: Immunogenicity and Safety Study in Ambulatory Adults of a Single Intramuscular Dose of SpikoGen Vaccine as a Heterologous or Homologous Booster Dose Following Completion of a Primary Course of Covid-19 Vaccine
ClinicalTrials.gov ID: NCT05542862
Acronym / sponsor ID: AUST-C19-booster
Conditions: COVID-19
Keywords: covid-19, vaccine, adjuvant, Spikogen, Advax, CpG55.2
Phase: Phase 3
Study type: Interventional
Recruitment status: Completed
Enrolment: 81 participants (actual)
Lead sponsor: Vaxine Pty LtdIndustry (pharma, biotech, devices)
Collaborators: Australian Respiratory and Sleep Medicine Institute, Cinnagen
Study start: 7 Sep 2022 (actual)
Primary completion: 31 Dec 2023 (actual)
Study completion: 16 Sep 2025 (actual)
First posted: 16 Sep 2022 (actual)
Results: Not posted in the source record

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

Detailed description

Study design

Primary purpose: Prevention
Allocation: Not applicable
Intervention model: Single group
Masking: None (open label)
Number of arms: 1
Model description: All subjects will receive the same single intervention with analysis groups being based on the type of primary vaccine received

Arm	Type	Receives
SpikoGen vaccine	Experimental	Biological: SpikoGen vaccineSingle booster dose of SpikoGen Covid-19 vaccine

Who may qualify

Ages: 18 years and older
Sex: All
Healthy volunteers: Accepted
Age groups: Adult, Older adult

Key inclusion criteria (4 listed)

Able to provide written informed consent
Males or females 18 years of age or older
Have previously had a primary course of Covid-19 vaccine with the most recent dose no less than 3 months previously.
Understand and are likely to comply with planned study procedures and be available for all study visits.

Key exclusion criteria (3 listed)

Allergy to Spikogen vaccine or one of its components, e.g. polysorbate 80.
Have received an experimental agent within 30 days prior to the study vaccination or expect to receive another experimental agent during the trial reporting period.
Any serious medical, social or mental condition which, in the opinion of the investigator, would be detrimental to the subjects or the study.

Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.

Interventions

Intervention	Type	Arms
SpikoGen vaccineAlso: Covax-19Recombinant spike protein based Covid-19 vaccine	Biological	SpikoGen vaccine

Primary outcome

Seroconversion
Time frame: Between baseline and 4 weeks post the booster dose
Proportion of study participants who seroconvert (4-fold or greater rise in serum spike antibody) by primary vaccine group
Seroprotection
Time frame: Between baseline and 4 weeks post the booster dose
Proportion of study participants who achieve a spike protein neutralisation titer of 32 or greater by primary vaccine group
Geometric mean titer fold change
Time frame: Between baseline and 4 weeks post the booster dose
Increase in Geometric mean titer of spike neutralisation antibodies by primary vaccine group
Safety assessment 1
Time frame: Occurring within 7 days after booster dose.
Frequency of Adverse events by primary vaccine group
Safety assessment 2
Time frame: Between time of administration of booster dose and through study completion, an average of 3 months
Frequency of Serious Adverse events by primary vaccine group
SARS-CoV-2 infection
Time frame: Between time of administration of booster dose and through study completion, an average of 3 months
Frequency of SARS-CoV-2 infections in study participants by primary vaccine group, age, gender, co-morbidities, and past infection
Antibody durability
Time frame: Between time of administration of booster dose and through study completion, an average of 3 months
The proportion of subjects who remain seroprotected throughout the duration of the study including broken down by primary vaccine group.
Seroconversion in participants with and without evidence of past infection
Time frame: Between baseline and 4 weeks post the booster dose and through study completion, an average of 3 months
Spike antibody seroconversion in baseline nuclear protein antibody positive versus negative participants by primary vaccine group
Seroprotection in participants with and without evidence of past infection
Time frame: Between baseline and 4 weeks post the booster dose and through study completion, an average of 3 months
Spike antibody seroprotection in baseline nuclear protein antibody positive versus negative participants by primary vaccine group
Spike antibody GMT in participants with and without evidence of past infection
Time frame: Between baseline and 4 weeks post the booster dose and through study completion, an average of 3 months
Spike antibody GMT in baseline nuclear protein antibody positive versus negative participants by primary vaccine group.

1 secondary outcome

Antibody correlates of protection
Time frame: Baseline and 4 weeks post the booster dose, and through study completion, an average of 3 months

Results and safety

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 17 Sep 2025.
Background: PubMed 35436611Tabarsi P, Anjidani N, Shahpari R, Mardani M, Sabzvari A, Yazdani B, Roshanzamir K, Bayatani B, Taheri A, Petrovsky N, Li L, Barati S. Safety and immunogenicity of SpikoGen(R), an Advax-CpG55.2-adjuvanted SARS-CoV-2 spike protein vaccine: a phase 2 randomized placebo-controlled trial in both seropositive and seronegative populations. Clin Microbiol Infect. 2022 Sep;28(9):1263-1271. doi: 10.1016/j.cmi.2022.04.004. Epub 2022 Apr 15.
Background: PubMed 35758850Tabarsi P, Anjidani N, Shahpari R, Roshanzamir K, Fallah N, Andre G, Petrovsky N, Barati S. Immunogenicity and safety of SpikoGen(R), an adjuvanted recombinant SARS-CoV-2 spike protein vaccine as a homologous and heterologous booster vaccination: A randomized placebo-controlled trial. Immunology. 2022 Nov;167(3):340-353. doi: 10.1111/imm.13540. Epub 2022 Jul 13.
Background: PubMed 35465982Li L, Honda-Okubo Y, Baldwin J, Bowen R, Bielefeldt-Ohmann H, Petrovsky N. Covax-19/Spikogen(R) vaccine based on recombinant spike protein extracellular domain with Advax-CpG55.2 adjuvant provides single dose protection against SARS-CoV-2 infection in hamsters. Vaccine. 2022 May 20;40(23):3182-3192. doi: 10.1016/j.vaccine.2022.04.041. Epub 2022 Apr 18.
Background: PubMed 34420786Li L, Honda-Okubo Y, Huang Y, Jang H, Carlock MA, Baldwin J, Piplani S, Bebin-Blackwell AG, Forgacs D, Sakamoto K, Stella A, Turville S, Chataway T, Colella A, Triccas J, Ross TM, Petrovsky N. Immunisation of ferrets and mice with recombinant SARS-CoV-2 spike protein formulated with Advax-SM adjuvant protects against COVID-19 infection. Vaccine. 2021 Sep 24;39(40):5940-5953. doi: 10.1016/j.vaccine.2021.07.087. Epub 2021 Aug 3.
Background: PubMed 36096430Tabarsi P, Anjidani N, Shahpari R, Mardani M, Sabzvari A, Yazdani B, Kafi H, Fallah N, Ebrahimi A, Taheri A, Petrovsky N, Barati S. Evaluating the efficacy and safety of SpikoGen(R), an Advax-CpG55.2-adjuvanted severe acute respiratory syndrome coronavirus 2 spike protein vaccine: a phase 3 randomized placebo-controlled trial. Clin Microbiol Infect. 2023 Feb;29(2):215-220. doi: 10.1016/j.cmi.2022.09.001. Epub 2022 Sep 10.
Derived from this study: PubMed 39914274Honda-Okubo Y, Sajkov D, Wauchope B, Turner JV, Vote B, Antipov A, Andre G, Lebedin Y, Petrovsky N. Immunogenicity and safety study of a single dose of SpikoGen(R) vaccine as a heterologous or homologous intramuscular booster following a primary course of mRNA, adenoviral vector or recombinant protein COVID-19 vaccine in ambulatory adults. Vaccine. 2025 Mar 7;49:126744. doi: 10.1016/j.vaccine.2025.126744. Epub 2025 Feb 5.
Individual participant dataSharing planned: No

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Referral and contact

AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.

Dimitar Sajkov, MD/PhD principal investigator

ARASMI

Nikolai Petrovsky, MD/PhD study director

Vaxine Pty Ltd

1 site in 1 country: see every site and its status.

Questions about this trial

What is this clinical trial studying?

A Phase 3 study testing SpikoGen vaccine in people with COVID-19, run by Vaxine Pty Ltd at 1 site in Australia.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 4 inclusion and 3 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: finished, as of the sponsor's last update on 17 Sep 2025. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in Australia. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

What does this phase mean?

Phase 3 studies compare the treatment with the current standard treatment or a placebo in a large group, to confirm how well it works and watch for side effects.

Not every study follows the same path, and some studies (observational studies, device studies) have no phase.

Are results available for this study?

The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.

How can a doctor refer a patient or contact the research team?

The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Seroconversion (time frame: Between baseline and 4 weeks post the booster dose). The study lists 10 primary outcomes in all. It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT05542862, which also lists 6 linked publications.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 17 Sep 2025.