SCB-2019

The vaccine was administered in 2 doses in 4 weeks.{{cite journal | vauthors = Richmond PC, Hatchuel L, Pacciarini F, Hu B, Smolenov I, Li P, Liang P, Han HH, Liang J, Clemens R | display-authors = 6 | title = Persistence of the Immune Responses and Cross-Neutralizing Activity With Variants of Concern Following 2 Doses of Adjuvanted SCB-2019 Coronavirus Disease 2019 Vaccine | journal = The Journal of Infectious Diseases | volume = 224 | issue = 10 | pages = 1699–1706 | date = November 2021 | pmid = 34480575 | pmc = 8499965 | doi = 10.1093/infdis/jiab447 | doi-access = free }}

In September 2021, SCB-2019 announced Phase III results showing 67.2% efficacy against all cases of COVID-19 of any degree of severity, 83.7% efficacy against moderate-to-severe disease, and 100% against hospitalisation and severe cases. Additionally, the vaccine was 79% effective against all cases of Delta. Of the 207 cases found during the trials, 52 were from the vaccinated group and 155 from the placebo group. These Phase II/III results have been published in the Lancet. {{cite journal | vauthors = Bravo L, Smolenov I, Han HH, Li P, Hosain R, Rockhold F, Clemens SA, Roa C, Borja-Tabora C, Quinsaat A, Lopez P, López-Medina E, Brochado L, Hernández EA, Reynales H, Medina T, Velasquez H, Toloza LB, Rodriguez EJ, de Salazar DI, Rodríguez CA, Sprinz E, Cerbino-Neto J, Luz KG, Schwarzbold AV, Paiva MS, Carlos J, Montellano ME, de Los Reyes MR, Yu CY, Alberto ER, Panaligan MM, Salvani-Bautista M, Buntinx E, Hites M, Martinot JB, Bhorat QE, Badat A, Baccarini C, Hu B, Jurgens J, Engelbrecht J, Ambrosino D, Richmond P, Siber G, Liang J, Clemens R | display-authors = 6 | title = Efficacy of the adjuvanted subunit protein COVID-19 vaccine, SCB-2019: a phase 2 and 3 multicentre, double-blind, randomised, placebo-controlled trial | journal = Lancet | volume = 399 | issue = 10323 | pages = 461–472 | date = January 2022 | pmid = 35065705 | pmc = 8776284 | doi = 10.1016/S0140-6736(22)00055-1 }}

Clover expects to submit its Phase III results for approval by the World Health Organization, European Medicines Agency, and China's NMPA in the fourth quarter of 2021.

In Phase III trials, SCB-2019 showed efficacy of 81.7% for moderate-to-severe cases of COVID-19 caused by Delta, 91.8% for Gamma, and 58.6% for Mu. 56 Delta cases, 37 Mu cases, and 13 Gamma cases were recorded during the trials.

Subunit vaccines contain parts of the virus selected to stimulate an immune response, without including the entire virus. Because the fragments are incapable of causing disease, subunit vaccines are considered very safe. Subunit vaccines in widespread use include the Hepatitis B vaccine and Pertussis vaccine.{{Cite web|title=What are protein subunit vaccines and how could they be used against COVID-19?|url=https://www.gavi.org/vaccineswork/what-are-protein-subunit-vaccines-and-how-could-they-be-used-against-covid-19|access-date=2021-07-08|website=www.gavi.org|language=en}}

SCB-2019 has a trimeric form of the SARS-CoV-2 spike protein (S-Trimer) combined with one of two different adjuvants AS03 (GlaxoSmithKline) or CpG/Alum (Dynavax).{{cite journal | vauthors = Hotez PJ, Bottazzi ME | title = Whole Inactivated Virus and Protein-Based COVID-19 Vaccines | journal = Annual Review of Medicine | volume = 73 | issue = 1 | pages = 55–64 | date = January 2022 | pmid = 34637324 | doi = 10.1146/annurev-med-042420-113212 | s2cid = 238747462 | doi-access = free }} The vaccine displays the spike protein in its natural three-part form, leading to a potentially better immune response. The vaccine is similar to other subunit COVID-19 vaccines including Novavax, Abdala, and ZF2001.{{Cite news| vauthors = Zimmer C, Corum J, Wee SL |title=Coronavirus Vaccine Tracker|language=en-US|work=The New York Times|date=10 June 2020 |url=https://www.nytimes.com/interactive/2020/science/coronavirus-vaccine-tracker.html|access-date=2021-07-08|issn=0362-4331}}

The vaccine is stable for at least six months under normal refrigeration conditions and at least one month at 40 degrees Celsius.

SCB-2019 is funded by CEPI as part of the COVAX. By November 2020, CEPI had invested $328 million to develop the vaccine. If the vaccine was successful, CEPI's investment would help scale-up production to over 1 billion doses a year.{{Cite web|title=CEPI extends partnership with Clover to fund COVID-19 vaccine candidate through global Phase 2/3 study to licensure | date = 3 November 2020 |url=https://cepi.net/news_cepi/cepi-extends-partnership-with-clover-to-fund-covid-19-vaccine-candidate-through-global-phase-2-3-study-to-licensure/|access-date=2021-07-08|website=CEPI|language=en-US}} Previously, CEPI provided $3.5 million to support Phase I trials and later an additional $66 million in July 2020 to expand clinical testing and prepare sites for Phase II/III trials.

In February 2021, Clover decided to proceed with the adjuvant from Dynavax for its Phase II/III trials over GlaxoSmithKline after evaluating manufacturing considerations.{{Cite news| vauthors = Liu R |date=2021-02-01|title=Clover ends COVID-19 vaccine partnership with GSK|language=en|work=Reuters|url=https://www.reuters.com/article/health-coronavirus-clover-gsk-idUSL1N2K70R6|access-date=2021-07-08}} Separately, CEPI provided $99 million funding to Dynavax to produce its adjuvant for various COVID-19 vaccines.

Vaccine production is expected to begin in 2021.

In June 2020, GAVI announced an agreement with Clover for the purchase of 64 million doses in 2021 and an additional 350 million doses in 2022.

In June 2020, Phase I trial were launched to assess safety, reactogenicity, and immunogenicity at multiple dose levels with 151 participants in Perth, Australia using 2 separate adjuvants, AS03 and CpG/Alum.{{ClinicalTrialsGov|NCT04405908|SCB-2019 as COVID-19 Vaccine}}{{cite web|date=20 June 2020|title=Clover Biopharmaceuticals starts Phase I Covid-19 vaccine trial|url=https://www.clinicaltrialsarena.com/news/clover-vaccine-covid-19-trial/|url-status=live|archive-url=https://web.archive.org/web/20201011084945/https://www.clinicaltrialsarena.com/news/clover-vaccine-covid-19-trial//|archive-date=11 October 2020|access-date=25 June 2020|publisher=Clinical Trials Arena}} In results published in The Lancet, SCB-2019 resulted in a strong immune responses against COVID-19, with high viral neutralizing activity (antibody geometric mean titres were 1567–4452 with AS03 and 174–2440 with CpG/Alum). Both adjuvanted vaccines were well tolerated and determined to be suitable for further clinical development.

In August 2021, a Phase II trial will launch to assess immunogenicity and safety with 800 participants in China.{{ClinicalTrialsGov|NCT04954131|Immunogenicity and Safety Study of Adjuvanted SARS-CoV-2 (SCB-2019) Vaccine in Adults in China}}

In March 2021, a larger combined-Phase II/III trial was launched to evaluate efficacy, immunogenicity, reactogenicity, and safety of the CpG/Alum adjuvated SCB-2019 vaccine.{{ClinicalTrialsGov|NCT04672395|A Controlled Phase 2/3 Study of Adjuvanted Recombinant SARS-CoV-2 Trimeric S-protein Vaccine (SCB-2019) for the Prevention of COVID-19 (SCB-2019)}} In July 2021, enrollment in the Phase II/III trials was completed with 45% of the 29,000 participants in Asia, 45% in Latin America and the rest in Europe and Africa.{{Cite web|title=Clover Biopharma completes enrollment in SPECTRA phase 2/3 trial of Covid-19 vaccine candidate, SCB-2019|url=http://www.pharmabiz.com/NewsDetails.aspx?aid=139809&sid=2|website=Pharmabiz|access-date=8 July 2021|archive-date=11 July 2021|archive-url=https://web.archive.org/web/20210711095641/http://www.pharmabiz.com/NewsDetails.aspx?aid=139809&sid=2|url-status=dead}}{{cite web |title=Clover Biopharmaceuticals Completes Enrollment of Adult and Elderly Population in SPECTRA Global Phase 2/3 Clinical Trial for its COVID-19 Vaccine Candidate |url=https://www.cloverbiopharma.com/news/77.html |website=cloverbiopharma.com |publisher=Clover Biopharmaceuticals |date=6 July 2021 |access-date=13 July 2021 |archive-date=6 July 2021 |archive-url=https://web.archive.org/web/20210706190823/https://www.cloverbiopharma.com/news/77.html |url-status=dead }}

In September 2021, results published in The Journal of Infectious Diseases showed SCB-2019 induced antibodies responses up to 184 days in the Phase I trial. Additionally, the vaccine produced neutralizing antibodies against three of the most common variants of concern; Alpha, Beta, and Gamma.{{cite journal | vauthors = Richmond PC, Hatchuel L, Pacciarini F, Hu B, Smolenov I, Li P, Liang P, Han HH, Liang J, Clemens R | display-authors = 6 | title = Persistence of the Immune Responses and Cross-Neutralizing Activity With Variants of Concern Following 2 Doses of Adjuvanted SCB-2019 Coronavirus Disease 2019 Vaccine | journal = The Journal of Infectious Diseases | volume = 224 | issue = 10 | pages = 1699–1706 | date = November 2021 | pmid = 34480575 | pmc = 8499965 | doi = 10.1093/infdis/jiab447 | doi-access = free }}

In September 2021, the COVID-19 vaccine candidate showed 79% efficacy against the delta variant in its Phase II/III trials. {{Cite web|title=Clover's COVID-19 shot tames delta in pivotal study, delivering boost to global vaccination campaign|url=https://www.fiercebiotech.com/biotech/clover-s-covid-19-shot-tames-delta-pivotal-study-delivering-boost-to-global-vaccination|access-date=2021-09-23|website=FierceBiotech|date=22 September 2021 |language=en}}

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Category:Protein subunit vaccines