Table 1 The development of vaccine candidates in phase 3 clinical stage

From: A systematic review of SARS-CoV-2 vaccine candidates

Vaccine type Vaccine Developer Clinical stage Number of doses Timing of doses Reported results of clinical trials Ref.
Inactivated vaccines The inactivated SARS-CoV-2 vaccine with aluminum hydroxide Sinovac Phase 3 2 0, 14 days Phase 2 trial showed that two doses of 6 μg/0.5 mL or 3 μg/0.5 mL of the vaccine were well-tolerated and immunogenic in healthy adults, with 3 μg dose eliciting 92.4% seroconversion under day 0, 14 schedule and 97.4% under day 0, 28 schedule. 43
Inactivated Wuhan Institute of Biological Products/Sinopharm Phase 3 2 0, 14 or 0, 21 days Phase 2 trial showed that the GMTs of NAbs were 121 and 247 at day 14 after 2 injections in participants receiving vaccine on days 0 and 14 and on days 0 and 21, respectively. Moreover, 7-day adverse reactions occurred in 6.0% and 19.0% of the participants receiving injections on days 0 and 14 vs on days 0 and 21. 44
Inactivated Beijing Institute of Biological Products/Sinopharm Phase 3 2 0, 14 or 0, 21 days N/A N/A
RNA vaccines BNT162b1 Pfizer/Fosun Pharma/BioNTech Phase 3 2 0, 28 days Phase 1/2 study showed that the vaccine caused mild to moderate local and systematic symptoms in most vaccinators and geometric mean neutralizing titers after the 10 and 30 µg dose 2 reached 1.8- to 2.8-fold that of COVID-19 convalescent sera panel. 48
mRNA-1273 Moderna/NIAID Phase 3 2 0, 28 days Phase 1 study reported that the two-dose vaccine series was not seriously toxic and it could elicit NAbs and Th1-biased CD4+ T-cell responses. 49
Non-replicating vector vaccines Adenovirus Type 5 Vector CanSino Biological Inc./Beijing Institute of Biotechnology Phase 3 1 N/A Phase 2 trial showed that the vaccine at a dose of 5 × 1010 viral particles per mL was safer than the vaccine at 1 × 10¹¹ viral particles and elicited comparable immune response to it. However, high pre-existing Ad5 immunity reduced NAbs response and influenced T-cell immune response. 55
ChAdOx1 nCoV-19 University of Oxford/AstraZeneca Phase 3 1 N/A Phase 1/2 trial reported that NAb responses were detected in 91% participants after a single dose when measured in MNA80 and in 100% participants when measured in PRNT50. After a booster dose, all participants had neutralizing activity. Local and systemic reactions, including pain, fever and muscle ache, could be reduced by paracetamol. 59
Adeno-based (rAd26-S + rAd5-S) Gamaleya Research Institute Phase 3 2 0, 21 days Phase 1/2 trial showed that administration of both rAd26-S and rAd5-S caused production of NAbs in 100% of participants on day 42 for both the lyophilized and frozen vaccine formulations. Cellular immune responses were detected in all participants at day 28. Moreover, the pre-existing immune response to the vectors rAd26 and rAd5 did not influence the titre of RBD-specific antibodies. 57
Ad26COVS1 Janssen Pharmaceutical Companies Phase 3 2 0, 56 days Preclinical trials showed that a single immunization with an Ad26 vector encoding a prefusion stabilized S antigen triggered robust NAb responses and provided complete or near-complete protection in rhesus macaques. The immunogen contains the wildtype leader sequence, the full-length membrane-bound S, mutation of the furin cleavage site, and two proline stabilizing mutations. 60