Safety, tolerability, and immunogenicity of a recombinant adenovirus type-5 vectored COVID-19 vaccine: a dose-escalation, open-label, non-randomised, first-in-human trial

Lancet. 2020 Jun 13;395(10240):1845-1854. doi: 10.1016/S0140-6736(20)31208-3. Epub 2020 May 22.

Abstract

Background: A vaccine to protect against COVID-19 is urgently needed. We aimed to assess the safety, tolerability, and immunogenicity of a recombinant adenovirus type-5 (Ad5) vectored COVID-19 vaccine expressing the spike glycoprotein of a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) strain.

Methods: We did a dose-escalation, single-centre, open-label, non-randomised, phase 1 trial of an Ad5 vectored COVID-19 vaccine in Wuhan, China. Healthy adults aged between 18 and 60 years were sequentially enrolled and allocated to one of three dose groups (5 × 1010, 1 × 1011, and 1·5 × 1011 viral particles) to receive an intramuscular injection of vaccine. The primary outcome was adverse events in the 7 days post-vaccination. Safety was assessed over 28 days post-vaccination. Specific antibodies were measured with ELISA, and the neutralising antibody responses induced by vaccination were detected with SARS-CoV-2 virus neutralisation and pseudovirus neutralisation tests. T-cell responses were assessed by enzyme-linked immunospot and flow-cytometry assays. This study is registered with ClinicalTrials.gov, NCT04313127.

Findings: Between March 16 and March 27, 2020, we screened 195 individuals for eligibility. Of them, 108 participants (51% male, 49% female; mean age 36·3 years) were recruited and received the low dose (n=36), middle dose (n=36), or high dose (n=36) of the vaccine. All enrolled participants were included in the analysis. At least one adverse reaction within the first 7 days after the vaccination was reported in 30 (83%) participants in the low dose group, 30 (83%) participants in the middle dose group, and 27 (75%) participants in the high dose group. The most common injection site adverse reaction was pain, which was reported in 58 (54%) vaccine recipients, and the most commonly reported systematic adverse reactions were fever (50 [46%]), fatigue (47 [44%]), headache (42 [39%]), and muscle pain (18 [17%]. Most adverse reactions that were reported in all dose groups were mild or moderate in severity. No serious adverse event was noted within 28 days post-vaccination. ELISA antibodies and neutralising antibodies increased significantly at day 14, and peaked 28 days post-vaccination. Specific T-cell response peaked at day 14 post-vaccination.

Interpretation: The Ad5 vectored COVID-19 vaccine is tolerable and immunogenic at 28 days post-vaccination. Humoral responses against SARS-CoV-2 peaked at day 28 post-vaccination in healthy adults, and rapid specific T-cell responses were noted from day 14 post-vaccination. Our findings suggest that the Ad5 vectored COVID-19 vaccine warrants further investigation.

Funding: National Key R&D Program of China, National Science and Technology Major Project, and CanSino Biologics.

Publication types

  • Clinical Trial, Phase I

MeSH terms

  • Adenoviridae
  • Adolescent
  • Adult
  • Antibodies, Neutralizing / blood
  • Antibodies, Viral / blood
  • Betacoronavirus
  • China
  • Coronavirus Infections / prevention & control*
  • Enzyme-Linked Immunosorbent Assay
  • Female
  • Humans
  • Immunity, Cellular
  • Immunity, Humoral
  • Injections, Intramuscular
  • Male
  • Middle Aged
  • Pandemics / prevention & control*
  • Pneumonia, Viral / prevention & control*
  • T-Lymphocytes / immunology
  • Vaccines, Synthetic / administration & dosage
  • Vaccines, Synthetic / adverse effects
  • Vaccines, Synthetic / therapeutic use
  • Viral Vaccines / administration & dosage*
  • Viral Vaccines / adverse effects
  • Viral Vaccines / therapeutic use
  • Young Adult

Substances

  • Antibodies, Neutralizing
  • Antibodies, Viral
  • COVID-19 vaccine
  • Vaccines, Synthetic
  • Viral Vaccines

Supplementary concepts

  • COVID-19
  • severe acute respiratory syndrome coronavirus 2

Associated data

  • ClinicalTrials.gov/NCT04313127