COVID-19 vaccine effectiveness
(Randomized evidence)

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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, N Engl J Med, 2021 (a)
ENSEMBLE

Full text
Commentary
Non replicating viral vector

Ad26.COV2.S, 5x10^10vp

Ad26.COV2.S, 1x10^11vp

0.9% saline 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, N Engl J Med, 2022 (b)
ENSEMBLE

Full text
Commentary
Non replicating viral vector

Ad26.COV2.S 5x10^10vp

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 Companies
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 , Clin. Infect. Dis., 2021 (b)

Full text
Commentary
Commentary
Non replicating viral vector

Ad5-nCoV 3x10¹⁰ 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