Vaccine Development & Clinical Trials

Front-Runner COVID-19 Vaccines

Pfizer-BioNTech

mRNA based vaccine by Expressing stabilized spike protein
Required 2 doses (3 weeks apart) and freezer storage at –70°C
Protective efficacy is 94%. A similar level of vaccine efficacy (94%) was observed for people older than 65.
The vaccine remains effective in a mass vaccination campaign in Israel.
Vaccination has resulted in the decrease in the rate of symptomatic COVID-19 by 94% and the rate of serious by 92%.

The company confirmed that the vaccine is effective against variants from the U.K. and South Africa.
In vitro study showed that the vaccine is slightly less protective against the variant from South Africa than original virus. Further study will be required for validation.

Moderna

Image by Marco Verch. License: https://creativecommons.org/licenses/by/2.0/

mRNA based vaccine by expressing stabilized spike protein
Required 2 doses (4 weeks apart) and freezer storage at –4°C
Provides protection against severe COVID-19 (protective efficacy: 94.5%).
In a small clinical trial, the participants maintained a strong immune response after three months of vaccination.
The company confirmed that the vaccine is effective against variants from the U.K. and South Africa.
In vitro study showed that the vaccine is slightly less protective against the variant from South Africa than original virus. Further study will be required for validation.

Oxford-AstraZeneca

Adenovirus vectored vaccine
Required 2 doses and storage at 2-8°C
Protective efficacy was 82.4% (two dose vaccination with interval of 12 weeks).
Vaccine provides similar level of protection against the variant from the UK compared to original virus.
In South Africa, AstraZeneca vaccination was halted since clinical trials did not show protection against mild or moderate illness. However, scientists are reevaluating the data to reconsider the vaccination against more severe cases of COVID-19.
On-going clinical trials by a combination of Oxford-AstraZeneca and Sputnik V vaccines
On-going clinical trial: participation of 300 Children in UK

Gamaleya (Sputnik V)

Image by Marco Verch.
License: https://creativecommons.org/licenses/by/2.0/

A heterologous recombinant adenovirus based vaccine
Required prime and boost (3 weeks apart) and storage at 2-8°C
Induces strong humoral and cellular immune responses
Vaccine efficacy was 91.6%
On-going clinical trials by a combination of Oxford-AstraZeneca and Sputnik V vaccines

Johnson & Johnson

Adenovirus vectored vaccine
Required a single dose and storage at 2-8°C
Clinical trials showed that 72% efficacy in the US and 57% efficacy in South Africa.
South Africa is considering using this vaccine. Although the vaccine provided 57% efficacy against moderate to severe COVID-19, it provided a better protection (85% efficacy) against severe disease after 28 days post-vaccination.
On-going phase 3 trial: use of two doses of vaccination

Novavax

Sinovac and Sinopharm

Type of Vaccine	Company	In Use
Adenovirus Vectored	Johnson & Johnson	Phase III for two dose vaccination
mRNA based	Moderna	Phase I (2 doses, 4 weeks apart); variant B.1.355 vaccine
Nanoparticle based	Novavax	Phase III (2 doses, 3 weeks apart)
mRNA based	CureVac	Phase III (2 doses, four weeks apart)
Protein based	Vector Institute	Phase III (2 doses, 3 weeks apart)
Virus-like particle	Medicago	Phase III (2 doses, 3 weeks apart)
Protein-adjuvant based	Anhui Zhifei Longcom	Phase III (3 doses, 4 weeks apart)
DNA-based	Zydus Cadila	Phase III (3 doses, 4 weeks apart)
DNA-based	AnGes	Phase III (2 doses, 2 weeks apart)
Subunit	Biological E	Phase III (2 doses, 4 weeks apart)
DNA-based	Inovio	Phase II/III (2 doses, 4 weeks apart)
Subunit	Clover	Phase II/III (2 doses, 3 weeks apart)
Virus-like particle	SK Bioscience	Phase I/II (2 doses, 4 weeks apart)
Protein based	Sanofi	Phase II (2 doses, 3 weeks apart)
mRNA based	Sanofi	Phase I/II (2 doses, 3 weeks apart)

Clinical trial phases

Phase 1: Evaluation of safety and antibody production

Phase 2: Evaluation of safety and immunogenicity by including a placebo group

Phase 3: Verification of safety, and efficacy in a large population group