The Johnson & Johnson COVID-19 vaccine is a COVID-19
vaccine that was developed by Janssen
Vaccines in Leiden, Netherlands, and
its Belgian parent company Janssen Pharmaceuticals, subsidiary
of American company Johnson & Johnson.
It is a viral
vector vaccine based on a human adenovirus that has been modified to contain the gene for making the spike protein of the SARS-CoV-2 virus that causes COVID-19. The body's immune system responds
to this spike protein to produce antibodies. The
vaccine requires only one dose and does not need to be stored frozen.
The vaccine started clinical trials in
June 2020, with Phase III trials involving around 43,000 people. On
29 January 2021, Janssen announced that 28 days after a completed vaccination, the vaccine was 66% effective in a one-dose regimen in preventing symptomatic COVID-19, with an 85% efficacy in preventing severe COVID-19, and 100% efficacy in preventing hospitalization or death caused by COVID-19.
The most common side
effects were pain at the injection site, headache, fatigue, muscle aches and nausea. Most of these side effects occurred within one to two
days following vaccination and were mild to moderate in severity and lasted one to two days.
The vaccine has been granted an Emergency
Use Authorization by the US Food and Drug Administration and
a conditional marketing authorisation by the European