| Vaccine description | |
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| Target | SARS-CoV-2 |
| Vaccine type | Protein subunit |
| Clinical data | |
| Routes of administration | Intramuscular |
| Identifiers | |
| CAS Number | |
| DrugBank | |
| Part ofa series on the |
| COVID-19 pandemic |
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Medical response |
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.svg) COVID-19 portal |
SCB-2019 is aprotein subunitCOVID-19 vaccine developed by Clover Biopharmaceuticals using anadjuvant from Dynavax technologies.[2] Positive results of Phase I trials for the vaccine were published inThe Lancet[3] and the vaccine completed enrollment of 29,000 participants in Phase II/III trials in July 2021.[4] In September 2021, SCB-2019 announced Phase III results showing 67% efficacy against all cases of COVID-19 and 79% efficacy against all cases of theDelta variant. Additionally, the vaccine was 84% effective against moderate cases and 100% effective against hospitalization.[5]
SCB-2019 is being funded byCEPI as part ofCOVAX[6] and has received advanced purchase orders fromGAVI for 400 million doses,[7] with production to begin in 2021.[8]
The vaccine was administered in 2 doses in 4 weeks.[9]
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.[5][8] Additionally, the vaccine was 79% effective against all cases ofDelta. Of the 207 cases found during the trials, 52 were from the vaccinated group and 155 from the placebo group.[5] These Phase II/III results have been published in the Lancet.[10]
Clover expects to submit its Phase III results for approval by theWorld Health Organization,European Medicines Agency, andChina's NMPA in the fourth quarter of 2021.[8]
In Phase III trials, SCB-2019 showed efficacy of 81.7% for moderate-to-severe cases of COVID-19 caused byDelta, 91.8% forGamma, and 58.6% forMu.[5][8] 56 Delta cases, 37 Mu cases, and 13 Gamma cases were recorded during the trials.[5]
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 theHepatitis B vaccine andPertussis vaccine.[11]
SCB-2019 has a trimeric form of the SARS-CoV-2 spike protein (S-Trimer) combined with one of two differentadjuvants AS03 (GlaxoSmithKline) or CpG/Alum (Dynavax).[12][3] The vaccine displays the spike protein in its natural three-part form, leading to a potentially better immune response.[6] The vaccine is similar to other subunit COVID-19 vaccines includingNovavax,Abdala, andZF2001.[13]
The vaccine is stable for at least six months under normal refrigeration conditions and at least one month at 40 degrees Celsius.[8]
SCB-2019 is funded byCEPI as part of theCOVAX. 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.[14] 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.[6]
In February 2021, Clover decided to proceed with the adjuvant from Dynavax for its Phase II/III trials over GlaxoSmithKline after evaluating manufacturing considerations.[15] Separately, CEPI provided $99 million funding to Dynavax to produce its adjuvant for various COVID-19 vaccines.[15]
Vaccine production is expected to begin in 2021.[8]
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.[2][7]
In June 2020, Phase I trial were launched to assess safety, reactogenicity, and immunogenicity at multiple dose levels with 151 participants inPerth, Australia using 2 separate adjuvants, AS03 and CpG/Alum.[16][17][2] In results published inThe 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.[3]
In August 2021, a Phase II trial will launch to assess immunogenicity and safety with 800 participants in China.[18]
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.[19][2] 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.[4][20]
In September 2021, results published inThe 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, andGamma.[21]
In September 2021, the COVID-19 vaccine candidate showed 79% efficacy against thedelta variant in its Phase II/III trials.[22]
