More than 100 SARS-CoV-2 vaccines are being investigated to help prevent COVID-19, the disease caused by the new coronavirus. While many of the candidates are still being evaluated in preclinical studies, here’s a look at some of the front runners that have made it into clinical development and are being tested in healthy volunteers.
Phase I trials are the first stage of clinical development and assess the safety, reactogenicity (ability to produce common or expected adverse events) and immunogenicity (ability to elicit an immune response) of the vaccines. Phase I trials are conducted in a small number of volunteers and at this stage low, medium and high doses of the vaccines are typically assessed and the best one(s) is selected for phase II and III trials. Phase II and III trials include many more participants and are conducted to assess how safe and effective each vaccine is.
A number of different types of vaccines are being investigated to prevent COVID-19, including traditional designs that contain inactivated virus. Other platform approaches are also being employed, including non-replicating adenoviral vector vaccines and mRNA (ribonucleic acid)-based vaccines. Currently there are no adenoviral vector vaccines or mRNA-based vaccines marketed for use in people.
Non-replicating viral vector vaccines
AZD1222 (ChAdOx1-S, ChAdOx-1 nCoV-19) - University of Oxford / AstraZeneca
Phase II/III development
In a preclinical trial, vaccination with AZD1222 did not stop rhesus macaques from becoming infected with SARS-CoV-2, but it did prevent the development of pneumonia in infected animals
AZD1222 is a SARS-CoV-2 vaccine for the prevention of COVID-19. The vaccine uses a recombinant viral vector called ChAdOx1, which is based on a weakened version of an adenovirus (common cold virus) that causes infections in chimpanzees. ChAdOx1 contains the genetic material of the spike protein from SARS-CoV-2. After vaccination the surface spike protein is produced, priming the immune system to fight off the COVID-19-causing virus. ChAdOx1 was chosen for its ability to induce a strong immune response and because it doesn’t replicate, so it is not able to cause an ongoing infection.
AZD1222 was developed by the Jenner Institute at the University of Oxford, which worked with the Oxford Vaccine Group. In April 2020, the University entered into a collaboration with AstraZeneca to develop and distribute the vaccine globally. AstraZeneca has since engaged with other organizations including Oxford Biomedica, the Coalition for Epidemic Preparedness Innovations (CEPI), Gavi the Vaccine Alliance and the World Health Organization (WHO) to support the manufacture and distribution of the vaccine. AstraZeneca reported on May 21, 2020 that it had received $US1bn from the US Biomedical Advanced Research and Development Authority (BARDA) to develop, produce and deliver the vaccine.
A phase II/III trial of AZD1222 was initiated in May 2020 to assess the safety and efficacy of the vaccine. It is expected to enroll 10,260 healthy volunteers. The phase II part of the trial will include volunteers aged from 5 to more than 70 year old and will assess the safety and immunogenicity of the vaccine. The phase III part of the trial assessing the vaccine’s efficacy - how well it works to prevent people from becoming infected and unwell - will only be conducted in volunteers over the age of 18. Adult volunteers will be randomized to receive one or two doses of AZD1222 or a control vaccine called MenACWY.
A phase I/II trial of the vaccine is also ongoing in healthy adult volunteers (aged 18-55) in the UK. It is planned to enroll 1112 volunteers.
In preclinical studies, vaccination with AZD1222 elicited an immune response in mice and rhesus macaques. Additionally, no pneumonia was observed in macaques exposed to SARS-CoV-2. There was also no evidence of immune-enhanced disease - an over-the-top immune response - after vaccinated animals were exposed to the virus. However, experts have highlighted that while the vaccine appeared to protect against pneumonia, it didn’t protect against catching the virus, as evidenced by the presence of the virus in the nasal secretions from both control and vaccinated macaques.
AstraZeneca expects to begin delivery of the vaccine in September 2020, should it prove to be effective.
Ad5-nCoV - CanSino Biological / Beijing Institute of Biotechnology, Academy of Military Medical Science
Phase II development
In preclinical studies, SARS-CoV-2 was not detectable in seven out of eight vaccinated ferrets following exposure to the virus, compared with only one of eight ferrets in the control group.
Like AZD1222, Ad5-nCoV uses a non-replicating adenoviral vector and expresses the spike glycoprotein of SARS-CoV-2. It is being developed by CanSino Biological and the Beijing Institute of Biotechnology.
A phase II trial of Ad5-nCoV is being conducted in 500 adult volunteers in China, following the completion of a phase I trial of the vaccine, which enrolled 108 participants. The phase I trial found the vaccine to be tolerable and stimulate the production of neutralizing antibodies and T-cell responses. Neutralizing antibody levels increased at least four-fold by day 28 in 75% of participants in the high-dose group, compared with 50% of patients in both the low- and middle-dose groups. Despite the high-dose vaccine being more immunogenic than the low- and middle-dose versions, the high-dose vaccine will not be evaluated in the phase II trial because it was associated with a larger number of expected or common adverse events.
One of the concerns with adenoviral vector vaccines is that many people who have previously been infected with the same cold virus. This could cause people to have high levels of neutralizing antibodies against the vector part of the vaccine already and this may lead to a weaker antibody response. Half of the people in CanSino’s study had high levels of neutralizing antibodies targeting adenovirus type 5 (Ad5), the vector used in this vaccine.
In preclinical studies, SARS-CoV-2 was not detectable in seven out of eight ferrets exposed to the virus after they had been vaccinated with Ad5-nCoV, compared with only one of eight ferrets in the control group.
In May 2020, CanSino partnered with Precision NanoSystems in Canada to develop a separate mRNA lipid nanoparticle (LNP) vaccine against COVID-19, which has not yet entered clinical development.
mRNA-1273 - Moderna / National Institute of Allergy and Infectious Diseases
Phase II development
Interim phase I results for mRNA-1273 raised questions and prompted the initiation of an investigation on behalf of investors
mRNA-1273 is a mRNA-based vaccine for the prevention of COVID-19, which is being developed in the US by Moderna and the National Institute of Allergy and Infectious Diseases (NIAID). Development of this vaccine is also being funded by a grant from BARDA, which provided $US483mil.
mRNA-based vaccines take a section of mRNA, which codes for a protein on the surface of a virus, and inserts it into a virus or liposome. When the vaccine is injected, the mRNA integrates into cells, the target protein is manufactured and the immune system reacts and attacks any virus it encounters. mRNA-1273 specifically encodes for the full-length, pre-fusion stabilized S (spike) protein of SARS-CoV-2.
A phase II trial of mRNA-1273 has been initiated and is enrolling 600 volunteers. The trial will evaluate the 50mcg (low) and 100mcg (middle) doses of the vaccine.
A phase III trial is expected to begin in July and all going well, doses of the vaccine are expected to be made available later this year.
BNT162 COVID-19 vaccine program (four candidates) - BioNTech / Fosun Pharma/ Pfizer
Phase I/II development
Initial clinical trials results expect in June or July 2020
BioNTech’s BNT162 COVID-19 vaccine program is evaluating four different mRNA-based vaccines to prevent COVID-19. They all make use of the company’s LNP mRNA vaccine platforms.
The four candidates have different mRNA formats and targets. One candidate contains uridine mRNA (uRNA), one contains self-amplifying mRNA (saRNA) and two contain nucleoside modified mRNA (modRNA). Two of the candidates target the larger spike sequence, while the other two target the smaller optimized receptor binding domain (RBD) of the SARS-CoV-2 spike protein.
BioNTech is a German biotech company which is collaborating with Fosun Pharma in China and Pfizer outside of China.
Phase I/II trials are being conducted in Germany and the US and are evaluating all four candidates. Low, middle and high doses (from 1-100mcg) of the vaccines are being tested in volunteers aged 18 years old and over. Two doses of each vaccine will be administered to volunteers, except for the saRNA candidate, which only requires one dose. The initial phase I part of the trial is being conducted in 200 volunteers in Germany and 360 volunteers in the US. If a candidate(s) appears to be safe and effective then a major study will start in September in several thousand participants. Doses of the vaccine could be available from October 2020.
Inactivated virus-based vaccines
Vero-cell derived inactivated COVID-19 vaccine - Wuhan Institute of Biological Products / Sinopharm
Phase I/II development
A vero-cell derived inactivated COVID-19 vaccine is being developed by the Wuhan Institute of Biological Products, which is part of the China National Pharmaceutical Group (Sinopharm Group), and the Wuhan Institute of Virology, which is part of the Chinese Academy of Sciences.
A phase I/II trial is underway in volunteers aged 6 years and over in China, which will assess three doses of the vaccine. In April 2020, the phase II part of the trial was initiated, just 12 days after phase I began. The initial phase I part of the trial enrolled 96 volunteers across three age groups. A total of 1456 volunteers are expected to be enrolled in the phase I/II trial.
Sinopharm expects that it will take more than a year to complete phase III development of the vaccine once that has been initiated.
Vero-cell derived inactivated COVID-19 vaccine - Beijing Institute of Biological Products / Sinopharm
Phase I/II development
Another phase I/II trial is also underway for a vero-cell derived inactivated COVID-19 vaccine in China, which is evaluating the vaccine in volunteers aged 3 and over. This vaccine is being developed by the Beijing Institute of Biological Products and Sinopharm.
On 31 May 2020, it was reported that phase II development of the vaccine had been completed and a final version of the vaccine could be available as early as the end of the year.
CoronaVac (PiCoVacc) - Sinovac
Phase I/II development
Three doses of CoronaVac (3 or 6mcg) provided partial or complete protection against SARS-CoV-2 in a preclinical trial conducted in rhesus macaques
CoronaVac is a purified inactivated SARS-CoV-2 virus vaccine candidate (PiCoVacc) being developed by Sinovac Biotech in China. One phase I/II trial is already enrolling volunteers and another is planned. The first phase I/II trial plans to enroll 744 volunteers adults aged 18-59 years old.
CoronaVac is reported to have induced neutralizing antibodies against SARS-CoV-2 in mice, rats and non-human primates in preclinical trials. In a trial conducted in rhesus macaques, three doses of CoronaVac (3 or 6mcg, a medium and high dose) provided partial or complete protection against SARS-CoV-2. Neutralizing antibodies were induced against 10 representative SARS-CoV-2 strains. Importantly, there was no evidence of immune-enhance disease (antibody-dependent enhancement, ADE) in the vaccinated macaques.
Planning for phase III development of CoronaVac, which is likely to take place in the UK, is being discussed. In May 2020, Sinovac secured $US15mil in funding to further the development of its vaccine.
Inactivated SARS-CoV-2 vaccine - Institute of Medical Biology, Chinese Academy of Medical Sciences
Phase I/II development
In May 2020, a phase I/II trial of an inactivated SARS-CoV-2 vaccine was initiated by the Chinese Academy of Medical Sciences in volunteers aged 18-59 years old. The trial is expected in enrol 942 participants and will assess low, medium and high doses of the vaccine. An initial dose of the vaccine will be followed by a booster dose 14 or 28 days later.
Protein subunit vaccines
NVX-CoV2373 - Novavax
Phase I/II development
In preclinical trials, NVX-CoV2373 is reported to have induced high levels of neutralizing antibodies against SARS-CoV-2
NVX-CoV2373 is a vaccine being developed by Novavax, a biotechnology company with sites in the US and Sweden. The vaccine makes use of Novavax’s recombinant nanoparticle technology to generate antigen derived from the spike protein of SARS-CoV-2. Two versions of the vaccine are being tested in the current clinical trial - one containing Novavax’s saponin-based Matrix-M adjuvant and one without. The adjuvant is designed to enhance the immune response generated by the vaccine.
A phase I of the vaccine is underway in Australia and will enrol 130 volunteers aged 18-59 years old. Preliminary results are expected in July. Phase II development will be carried out in the US and other countries.
In May 2020, Novavax reported that the CEPI will invest up to $US384mil on top of the $US4mil it has already invested to further the development of NVX-CoV2373. And on June 3, 2020, Novavax announced an agreement with AGC Biologics, under which the Japanese manufacturer will up-scale the production of the company’s Matrix-M adjuvant. Like the other vaccine developers, Novavax hopes to have a vaccine available in late 2020 or early 2021.
INO-4800 - Inovio Pharmaceuticals
Phase I development
INO-4800 induced neutralizing antibodies and T cell responses targeting SARS-CoV-2 in preclinical studies
INO-4800 is in phase I development in the US for the prevention of COVID-19. INO-4800 is a synthetic DNA-based vaccine that targets the spike protein of SARS-CoV-2. It is being developed by Inovio Pharmaceuticals using its DNA medicine platform.
Unlike other vaccines that are administered via intramuscular injection, this vaccine is administered via intradermal injection followed by electroporation using the CELLECTRA 2000 device. Volunteers enrolled in the phase I trial will be administered either one or two doses of the vaccine given 4 weeks apart.
Phase I results are expected in June 2020 and the company plans to move the vaccine into phase II/III development by fall of this year. A million doses of the vaccine are also planned to be available by the end of the year.
Inovio has entered into a number of collaborations and is receiving funding to further the development of INO-4800, including $US17.2mil in funding that it has received from CEPI. Invovio is also working with Beijing Advaccine in China and the International Vaccine Institute in South Korea. It is also working with Public Health England (PHE) and Commonwealth Scientific and Industrial Research Organisation (CSIRO) in Australia, as well as other organizations.
Many other candidates and questions
In addition to the vaccine candidates that have made it into clinical development, there are many more in preclinical development that may prove to be effective. As companies race to deliver a vaccine before the end of the year, cautious optimism has been expressed by experts such as Dr. Anthony Fauci. However, more research still needs to be done and many more questions need to be answered including:
What level of response to the vaccine do we need to confer immunity - what level of neutralizing antibodies are needed?
How long will a vaccine provide protection for?
How quickly can the vaccine be made available to all?
- World Health Organization (WHO). DRAFT landscape of COVID-19 candidate vaccines – 30 May 2020. Available at: https://www.who.int/who-documents-detail/draft-landscape-of-covid-19-candidate-vaccines. [Accessed June 5, 2020].
- van Doremalen, Lambe T, Spencer A, et al. ChAdOx1 nCoV-19 vaccination prevents SARS-CoV-2 pneumonia in rhesus macaques. bioRxiv preprint. May 13, 2020 doi: https://doi.org/10.1101/2020.05.13.093195. [Accessed June 5, 2020].
- Science Media Centre (SMC). Expert reaction to preprint on the ChAdOx1 nCoV-19 vaccine and SARS-CoV-2 pneumonia in rhesus macaques. May 14, 2020. Available at: https://www.sciencemediacentre.org/expert-reaction-to-preprint-on-the-chadox1-ncov-19-vaccine-and-sars-cov-2-pneumonia-in-rhesus-macaques/. [Accessed June 5, 2020].
- The Telegraph. Doubts over Oxford vaccine as it fails to stop coronavirus in animal trials. May 18, 2020. Available at: https://www.telegraph.co.uk/global-health/science-and-disease/doubts-oxford-vaccine-fails-stop-coronavirus-animal-trials/. [Accessed June 5, 2020].
- University of Oxford. Oxford COVID-19 vaccine to begin phase II/III human trials. May 22, 2020. Available at: http://www.ox.ac.uk/news/2020-05-22-oxford-covid-19-vaccine-begin-phase-iiiii-human-trials. [Accessed June 5, 2020].
- EU Clinical Trials Register. A phase 2/3 study to determine the efficacy, safety and immunogenicity of the candidate Coronavirus Disease (COVID-19) vaccine ChAdOx1 nCoV-19. Available at: https://www.clinicaltrialsregister.eu/ctr-search/trial/2020-001228-32/GB. [Accessed June 5, 2020].
- EU Clinical Trials Register. A phase I/II study to determine efficacy, safety and immunogenicity of the candidate Coronavirus Disease (COVID-19) vaccine ChAdOx1 nCoV-19 in UK healthy adult volunteers. Available at: https://www.clinicaltrialsregister.eu/ctr-search/trial/2020-001072-15/GB. [Accessed June 5, 2020].
- AstraZeneca. AstraZeneca and Oxford University announce landmark agreement for COVID-19 vaccine. April 30, 2020. Available at: https://www.astrazeneca.com/content/astraz/media-centre/press-releases/2020/astrazeneca-and-oxford-university-announce-landmark-agreement-for-covid-19-vaccine.html. [Accessed June 5, 2020].
- ChiCTR, Chinese Clinical Trial Registry. A randomized, double-blinded, placebo-controlled phase II clinical trial for Recombinant Novel Coronavirus (2019-nCOV) Vaccine (Adenovirus Vector). Available at: http://www.chictr.org.cn/showprojen.aspx?proj=52006. [Accessed June 5, 2020].
- ChiCTR, Chinese Clinical Trial Registry. A phase I clinical trial for recombinant novel coronavirus (2019-COV) vaccine (adenoviral vector). Available at: http://www.chictr.org.cn/showprojen.aspx?proj=51154. [Accessed June 5, 2020].
- Zhu F-C, Li Y-H, Guan X-H, et al. Safety, tolerability, and immunogenicity of a recombinant adenovirus type-5 vectored COVID-19 vaccine: a dose-escalation, open-label, non-randomised, first-in-human trial. [published online ahead of print, 2020 May 22]. Lancet. 2020;S0140-6736(20)31208-3. doi:10.1016/S0140-6736(20)31208-3.
- Nature Biotechnology. Questions remain following first COVID-19 vaccine results. May 28, 2020. Available at: https://www.nature.com/articles/d41587-020-00015-x. [Accessed June 5, 2020].
- BioSpace. China's CanSinoBIO Partners with Canada's Precision NanoSystems on COVID-19 Vaccine. May 21, 2020. Available at: https://www.biospace.com/article/china-biotech-cansino-biologics-inks-covid-19-vaccine-deal-with-precision-nanosystems/. [Accessed June 5, 2020].
- ClinicalTrials.gov. Dose-Confirmation Study to Evaluate the Safety, Reactogenicity, and Immunogenicity of mRNA-1273 COVID-19 Vaccine in Adults Aged 18 Years and Older. Available at: https://clinicaltrials.gov/ct2/show/NCT04405076?term=moderna&cond=covid-19&draw=2&rank=1. [Accessed June 5, 2020].
- Business Wire. Moderna Announces First Participants in Each Age Cohort Dosed in Phase 2 Study of mRNA Vaccine (mRNA-1273) Against Novel Coronavirus. May 29, 2020. Available at: https://www.businesswire.com/news/home/20200529005628/en/Moderna-Announces-Participants-Age-Cohort-Dosed-Phase. [Accessed June 5, 2020].
- Moderna. Moderna Announces Award from U.S. Government Agency BARDA for up to $483 Million to Accelerate Development of mRNA Vaccine (mRNA-1273) Against Novel Coronavirus. April 16, 2020. Available at: https://investors.modernatx.com/news-releases/news-release-details/moderna-announces-award-us-government-agency-barda-483-million. [Accessed June 5, 2020].
- BioNTech. BioNTech, BNT162 COVID-19 Vaccine Program Update. April 23, 2020. Available at: https://investors.biontech.de/static-files/398d9bd8-e2cb-49ca-9d6d-7dfd01c66b8a. [Accessed June 5, 2020].
- ClincalTrials.gov. Search results BNT162 + COVID. Available at: https://clinicaltrials.gov/ct2/results?cond=covid&term=BNT162&cntry=&state=&city=&dist=. [Accessed June 5, 2020].
- Fierce Biotech. Pfizer, BioNTech to ramp up COVID-19 vaccine tests, plot major trial boost in fall. May 13, 2020. Available at: https://www.fiercebiotech.com/biotech/pfizer-biontech-to-ramp-up-covid-19-vaccine-tests-plots-major-trial-boost-fall. [Accessed June 5, 2020].
- GlobeNewswire. BioNTech Announces First Quarter 2020 Financial Results and Corporate Progress. May 12, 2020. Available at: https://www.globenewswire.com/news-release/2020/05/12/2031879/0/en/BioNTech-Announces-First-Quarter-2020-Financial-Results-and-Corporate-Progress.html. [Accessed June 5, 2020].
- ChiCTR, Chinese Clinical Trial Registry. A randomized, double-blind, placebo parallel-controlled phase I/II clinical trial for inactivated Novel Coronavirus Pneumonia vaccine (Vero cells). Available at: http://www.chictr.org.cn/showprojen.aspx?proj=52227. [Accessed June 5, 2020].
- Xinhua Net. China's inactivated COVID-19 vaccine enters 2nd-phase clinical trial. Available at: http://www.xinhuanet.com/english/2020-04/25/c_139005855.htm. [Accessed June 5, 2020].
- Xinhua Net. China Focus: How Chinese researchers develop inactivated COVID-19 vaccines. Available at: http://www.xinhuanet.com/english/2020-04/20/c_138992285.htm. [Accessed June 5, 2020].
- Caixin. Another Chinese Coronavirus Vaccine Candidate Enters Phase-Two Human Trials. April 25, 2020. Available at: https://www.caixinglobal.com/2020-04-25/another-chinese-coronavirus-vaccine-candidate-enters-phase-two-human-trials-101547174.html. [Accessed June 5, 2020].
- ChiCTR, Chinese Clinical Trial Registry. A phase I/II clinical trial for inactivated novel coronavirus (2019-CoV) vaccine (Vero cells). Available at: http://www.chictr.org.cn/showproj.aspx?proj=53003. [Accessed June 5, 2020].
- TrialSiteNews. China’s Beijing Institute of Biological Product’s COVID-19 Vaccine Reportedly Ready for Phase III? May 31, 2020. Available at: https://www.trialsitenews.com/chinas-beijing-institute-of-biological-products-covid-19-vaccine-reportedly-ready-for-phase-iii/. [Accessed June 5, 2020].
- ClinicalTrials.gov. Safety and Immunogenicity Study of Inactivated Vaccine for Prevention of SARS-CoV-2 Infection(COVID-19). Available at: https://clinicaltrials.gov/ct2/show/NCT04383574?term=covid-19&cond=vaccine&cntry=CN&draw=2. [Accessed June 5, 2020].
- ClinicalTrials.gov. Safety and Immunogenicity Study of Inactivated Vaccine for Prophylaxis of SARS CoV-2 Infection (COVID-19). Available at: https://clinicaltrials.gov/ct2/show/NCT04352608?term=Sinovac&cntry=CN&draw=2. [Accessed June 5, 2020].
- HospiMedica. Chinese Firm Sinovac Biotech Says It Is 99% Sure that Its COVID-19 Vaccine Will Work. June 1, 2020. Available at: https://www.hospimedica.com/covid-19/articles/294782702/chinese-firm-sinovac-biotech-says-it-is-99-sure-that-its-covid-19-vaccine-will-work.html. [Accessed June 5, 2020].
- Gao Q, Bao L, Mao H, et al. Development of an inactivated vaccine candidate for SARS-CoV-2. Science. 06 May 2020:
eabc1932. DOI: 10.1126/science.abc1932.
- Reuters. BRIEF-Sinovac Secures $15 Mln In Funding To Accelerate COVID-19 Vaccine Development. May 23, 2020. Available at: https://www.reuters.com/article/brief-sinovac-secures-15-mln-in-funding/brief-sinovac-secures-15-mln-in-funding-to-accelerate-covid-19-vaccine-development-idUSFWN2D40JX. [Accessed June 5, 2020].
- ClinicalTrials.gov. Evaluation of the Safety and Immunogenicity of a SARS-CoV-2 rS (COVID-19) Nanoparticle Vaccine With/Without Matrix-M Adjuvant. Available at: https://clinicaltrials.gov/ct2/show/NCT04368988?term=vaccine&recrs=a&cond=covid-19&draw=2&rank=10. [Accessed June 5, 2020].
- Novavax. Novavax Initiates Phase 1/2 Clinical Trial of COVID-19 Vaccine. May 25, 2020. Available at: http://ir.novavax.com/news-releases/news-release-details/novavax-initiates-phase-12-clinical-trial-covid-19-vaccine. [Accessed June 5, 2020].
- Novavax. Novavax Identifies Coronavirus Vaccine Candidate; Accelerates Initiation of First-in-Human Trial to Mid-May. April 8, 2020. Available at: https://ir.novavax.com/news-releases/news-release-details/novavax-identifies-coronavirus-vaccine-candidate-accelerates. [Accessed June 5, 2020].
- Novavax. Novavax to Receive up to $388 Million Funding from CEPI for COVID-19 Vaccine Development and Manufacturing. May 11, 2020. Available at: http://ir.novavax.com/news-releases/news-release-details/novavax-receive-388-million-funding-cepi-covid-19-vaccine. [Accessed June 5, 2020].
- Fierce Pharma. Novavax enlists AGC Biologics to manufacture adjuvant for COVID-19 shot. June 3, 2020. Available at: https://www.fiercepharma.com/manufacturing/novavax-enlists-agc-biologics-to-manufacture-adjuvant-for-covid-19-shot. [Accessed June 5, 2020].
- ClinicalTrials.gov. Safety and Immunogenicity Study of an Inactivated SARS-CoV-2 Vaccine for Preventing Against COVID-19. Available at: https://clinicaltrials.gov/ct2/show/NCT04412538. [Accessed June 5, 2020].
- ClinicalTrials.gov. Safety, Tolerability and Immunogenicity of INO-4800 for COVID-19 in Healthy Volunteers. Available at: https://clinicaltrials.gov/ct2/show/NCT04336410?term=inovio&cond=covid-19&draw=2&rank=1. [Accessed June 5, 2020].
- Inovio Pharmaceuticals. INOVIO's COVID-19 DNA Vaccine INO-4800 Demonstrates Robust Neutralizing Antibody and T Cell Immune Responses in Preclinical Models. May 20, 2020. Available at: http://ir.inovio.com/news-releases/news-releases-details/2020/INOVIOs-COVID-19-DNA-Vaccine-INO-4800-Demonstrates-Robust-Neutralizing-Antibody-and-T-Cell-Immune-Responses-in-Preclinical-Models/default.aspx. [Accessed June 5, 2020].
- Smith, TRF, Patel A, Ramos S, et al. Immunogenicity of a DNA vaccine candidate for COVID-19. Nat Commun 11, 2601 (2020). https://doi.org/10.1038/s41467-020-16505-0.
- Inovio Pharmaceuticals. INOVIO Expands Manufacturing of COVID-19 DNA Vaccine INO-4800 With New Funding from CEPI. April 30, 2020. Available at: http://ir.inovio.com/news-releases/news-releases-details/2020/INOVIO-Expands-Manufacturing-of-COVID-19-DNA-Vaccine-INO-4800-With-New-Funding-from-CEPI/default.aspx. [Accessed June 5, 2020].
- Inovio Pharmaceuticals. Inovio Urgently Focused on Developing COVID-19 Vaccine Because the World Can't Wait. Available at: https://www.inovio.com/our-focus-serving-patients/covid-19/. [Accessed June 5, 2020].
- The Wall Street Journal. Fauci 'Cautiously Optimistic' About Coronavirus Vaccine. June 2, 2020. Available at: https://www.wsj.com/articles/fauci-cautiously-optimistic-about-coronavirus-vaccine-11591132326. [Accessed June 6, 2020].