Table 1.

Vaccines approaches being taken and the number of candidate vaccines in clinical and pre-clinical trials (20 August 2020).

Vaccine platform	Construct details	Number in pre-clinical trials	Number in clinical trials
Live attenuated virus	Codon-pair deoptimized live attenuated vaccines	3	0
Inactivated whole virus	Some combined with alum or CpG 1018 adjuvant	9	5
Protein/peptide subunit	Recombinant whole S protein, RBD or S1; 1 molecular clamp stabilized; 1 based on N protein; nanoparticle/VLP; peptides in LNP; 1 li-key peptide-based; OMV-based With or without adjuvant and/or fused with Fc subunit of IgG Most intramuscular delivery; 1 microneedle array, 1 oral construct	50	8
Non-replicating viral vectors	Chimp adenovirus 1; human adenovirus (Ad5, Ad 26); adeno-associated virus (AAV); influenza virus (H1N1); modified vaccinia Ankara (MVA); parainfluenza virus 5 (PIV5); rabies virus; Sendai virus With or without adjuvant Most intramuscular delivery; 1 subcutaneous and several oral constructs	19	5
Replicating viral vectors	Avian paramyxovirus; horsepox; influenza; measles; Newcastle disease virus (NDV); vesicular stomatitis virus (VSV); Yellow fever virus (YF17D) Most intramuscular delivery; 2 intranasal	17	1
DNA	DNA plasmid vaccines; mostly S protein or RBD-based, but 2 also with N protein With or without adjuvant Most intramuscular delivery; some with electroporation/needle free delivery; 1 oral vaccine (bacTRL-Spike)	12	4
RNA	LNP-encapsulated encoding spike protein or RBD; self-amplifying Most intramuscular delivery; 1 intranasal	16	6
Virus like particle (VLP)	Whole virus, protein and peptides inside or on surface; lentivirus, baculovirus, HIV-based vehicles Some with adjuvants	12	1

Adapted from WHO Draft Landscape of COVID-19 Vaccines [ref].