COVID-19 vaccine effectiveness
(Randomized evidence)

Trial Type Comparisons Design Participants Sample size Overall risk
of bias
Highest assessment
Full description
Intervention 1 Intervention 2
NCT04436276
Janssen Pharmaceutical Companies
Sadoff J(1), N Engl J Med, 2021
ENSEMBLE

Full text
Commentary
Non replicating viral vector

Ad26.COV2.S

Ad26.COV2.S 1x10^11vp

Placebo

RCT
Phase 1-2
Healthy SARS-CoV-2 nucleic acid negative adults 18-55 years old and elderly >65 years old in multiple centres in Belgium and the US N=810
Low
Details

Full description

NCT04505722
Janssen Pharmaceutical Companies
Sadoff J(2), N Engl J Med, 2021
ENSEMBLE

Full text
Commentary
Non replicating viral vector

Ad26.COV2.S

Placebo

RCT
Phase 3
Adults >18 years of age at 213 centers in Argentina, Brazil, Chile, Colombia, Mexico, Peru, South Africa and USA N=44325
Some concerns
Details

Full description

NCT04436276
Janssen Pharmaceutical (Johnson & Johnson)
Stephenson K, JAMA, 2021

Full text
Commentary
Commentary
Non replicating viral vector

Ad26.COV2.S

Placebo

RCT
Phase 1
Healthy adults aged 18-55 years that were SARS-CoV-2 infection-free in a single centre in USA. N=10
Low
Details

Full description

NCT04566770
CanSino Biological Inc./Beijing Institute of Biotechnology
Zhu F (2), Clin. Infect. Dis., 2021

Full text
Commentary
Commentary
Non replicating viral vector

Ad5-vectored 3×10^10 vp

Placebo

RCT
Phase 2b
Healthy children and adolescents aged 6-17 years that were HIV-negative and SARS-CoV-2 infection-free in a single centre in China. N=150
Low
Details

Full description