The pharmaceutical giant’s jab was approved by European Union regulators in mid-March, following approval of vaccines made by Pfizer-BioNTech, Moderna and AstraZeneca.
The 27-nation EU has signed a firm order for 200 million J&J doses and an option for 200 million more.
As well as being the first that requires just a single injection rather than two, the Johnson & Johnson vaccine is easier to store.
The EMA gave the green light after saying clinical trials involving volunteers in the United States, South Africa and South American countries found the J&J jab was 67 percent effective at preventing people from getting Covid.
The jab was the fourth to be endorsed for use in the EU after vaccines from Pfizer-BioNTech , AstraZeneca-Oxford University and Moderna, and is recommended for those over 18 years of age, the European Medicines Agency (EMA) said.
“With this latest positive opinion, authorities across the European Union will have another option to combat the pandemic and protect the lives and health of their citizens. This is the first vaccine that can be used as a single dose,” said Emer Cooke, EMA’s Executive Director after the jab was approved.
The study said the side effects from the COVID-19 Janssen vaccine were usually mild or moderate and cleared within a couple of days after vaccination, the EMA said.
Several European countries have enacted new restrictions to curb a surge of infections, as vaccination campaigns have been slower than in other countries such as the United States or Britain.