Spanish regions are likely to begin using Johnson & Johnson's coronavirus vaccine to inoculate 70-79 year olds on Thursday, Health Minister Carolina Darias said on Wednesday.
Spain has already distributed the first batch of vials to regional health authorities, which are in charge of administering the injections.
"Regions will surely start tomorrow because they want to increase the pace of vaccination," Darias told a news briefing.
An initial shipment of 146,000 doses of the single-shot drug landed in Spain last week but they were impounded in a warehouse on arrival over concerns the vaccines cause a rare type of clotting disorder.
Spanish health authorities had been waiting for updated guidance from Europe's EMA drug regulator, which announced on Tuesday a possible link between the shot and blood clots, but said the benefits outweighed any risks.
A warning about unusual blood clots with low platelets must be added to the vaccine's labels.
After a slow start, the national vaccination campaign has gathered pace and the health ministry gave out a record 456,777 doses in the past 24 hours.
Despite various supply disruptions, Spain still expects to have half of its 47 million population fully inoculated by late July. So far around 7.6% have received a full course while nearly 21% have received at least one dose.
Data released on Wednesday showed the 14-day infection rate was practically flat at 229 cases per 100,000 people, after rising steadily for the past few weeks.
The health ministry added 10,232 cases to its tally, bringing the total to nearly 3.45 million, while the death toll climbed by 148 to 77,364.
(Reporting by Belen Carreno and Nathan Allen, editing by Andrei Khalip, William Maclean)
