Johnson & Johnson began delivering its single-dose COVID shot to European Union countries on Monday (April 12).
Shipments were meant to start leaving warehouses at the beginning of April, but production issues delayed the European rollout.
The vaccine is mainly used in the United States currently. It's one of four approved for use by Brussels.
Johnson & Johnson, a U.S. company, has committed to delivering 55 million doses to the EU by the end of June and another 120 million in the third quarter, the EU announced this month.
The company confirmed it began deliveries to EU countries plus Norway and Iceland, but it declined to comment on supplies for April and the second quarter.
Spain and Italy were among countries expecting supplies this week and relying on them to boost sluggish vaccination campaigns.
Spain said on Monday it would initially prioritize people aged 70-79 for vaccination with the Johnson & Johnson shot.
The other EU-approved vaccines - Moderna, Pfizer/BioNTech and AstraZeneca - all require two doses instead.