Barely a month after the country ended its state of emergency, cities including Barcelona, Zaragoza, and the capital Madrid have seen a surge in new infections, prompting the government to warn that a second wave could be imminent.
The government of Catalonia now says all nightclubs and late-night bars in the region are to close for the next two weeks. The Spanish defense ministry is also implementing an early response tracker system to prevent any upturn in cases in the military.
The health ministry reported more than 900 new cases of the virus. One football team in the second division, Fuenlabrada, now has 28 confirmed cases. Contagion among young people is a particular worry, as they have been gathering in large numbers in cities at night.
Epidemiologist Dr. Daniel Lopez-Acuna told the average age of cases could rise "because the transmission is going from the youngsters to the rest of the household, and certainly the elderly".
The UK says all those returning from Spain must self-isolate for 14 days. This includes the Canary Islands and the Balearic Islands, although those destinations are not included in the UK's new general warning to avoid all but essential travel to mainland Spain.
Norway has said it would also start quarantining people arriving from Spain, while France has warned its citizens not to travel to Catalonia.
Belgium has banned travel to Huesca and Lleida, with recommendations against travel to a number of other areas in Spain.
A Spanish foreign ministry spokeswoman said the country was safe, with only localized, isolated and controlled outbreaks.