Madrid health authorities on Friday confirmed the region's first case of the Brazilian COVID-19 variant, while a national committee was debating whether to recommend AstraZeneca's vaccine to people over 65.
The national health ministry said it was not aware of any other cases of the highly contagious Brazilian variant in Spanish territory.
Catalan authorities announced the country's second known case of the South African variant on Wednesday, a day after the government restricted air travel with Brazil and South Africa to curb the spread of the virulent new strains from those countries.
Officials have warned that although a third wave of infection has slowed, with the 14-day incidence rate falling to 751 cases per 100,000 people on Friday from 900 cases in late January, the arrival of the new strains could drive a resurgence.
The health ministry recorded 28,565 new cases on Friday, bringing the total above 2.94 million, while the death toll climbed by 584 to 61,386.
Meanwhile a national vaccine committee was expected to announce that Spain would follow France and Germany in restricting the AstraZeneca vaccine to younger people amid a lack of data on its use in the elderly.
Nearly three quarters of Spaniards are willing to receive a shot as soon as one became available, according to a recent poll by the Centre for Sociological Studies (CIS) but some remain wary.