The Delta variant of Covid-19 and a surge in infections among younger, unvaccinated people have catapulted Spain’s coronavirus rate to the highest in mainland Europe, according to Financial Times research.

Infection rates in the country have rocketed over the past week, surpassing both Portugal and Russia, with the seven-day rate almost tripling from 58 cases per 100,000 on June 29 to 156 on Tuesday. Spain still slightly lags behind Portugal on the 14-day rate more widely used in the EU.

In response to the rise, the Catalonia region — the worst affected in the country — said on Tuesday it was reintroducing restrictions on nightlife, while Castile-León called for a return to a curfew system.

Spain’s rise in infections has been fuelled by a dramatic increase among 12-29-year-olds, among whom infections are roughly 20 times as common as for the over-70s.

The Spanish government has attributed much of the rise to social gatherings — including outdoor drinking sessions where young people share bottles — and to greater mobility at a time when people are travelling within Spain on holiday. The country scrapped almost all of its national Covid restrictions in May.

But FT research, based on random samples taken by Spanish authorities, indicates that the more infectious Delta variant now accounts for some 30 per cent of all cases and is set to become dominant around July 17. 

Spain’s trajectory is moving it closer to infection levels in the UK — which is ending coronavirus curbs on July 19 — with both countries gambling that the rise in cases among younger and largely unvaccinated people will not lead to graver problems among older, more vulnerable groups.

The EU country with the highest infection rate is Cyprus, with a seven-day rate of 424, while the UK, where Delta is predominant, has a rate of 267.

The jump in cases in Spain comes at a delicate time for its tourism-dependent economy, in which the months of July and August are crucial.

“We still think it is realistic to forecast that by year end we will achieve at least half the [tourism] figures of 2019,” Reyes Maroto, Spain’s tourism minister, told the FT. She argued that Spain’s rising number of inoculations — 41 per cent of the population is fully vaccinated — was more significant than infection rates “to measure country risk” and that Spain remained “a safe tourist destination”.

As of last Friday, infection rates passed the threshold for classifying Spain as “red” according to EU guidelines, which means travel to and from the country should be discouraged.

“I don’t see the Delta variant as a game changer given the high vaccination rate among the vulnerable Spanish population and indeed among the British population as a whole,” said Professor Fernando Rodríguez Artalejo, an epidemiologist at the Autonomous University of Madrid. 

“It is true there are many infections, but neither here nor in the UK is it producing a relevant increase in hospitalisations. The probably very negative impact on tourism is another question,” he said.

The Spanish government hopes new UK rules, to be unveiled this week, will boost British tourism to mainland Spain despite the surge in cases by dispensing with quarantine requirements for the fully vaccinated.

Both Spain and Portugal reject arguments that opening up to British tourists has led to an increase in the Delta variant. Fernando Simón, the doctor helping lead Spain’s push against coronavirus, emphasised that UK tourists have to show either a negative test or vaccination documentation before entering the country. 

In Portugal, where the Delta variant accounts for 70 per cent of cases, António Costa, prime minister, argues that it arrived not from the UK but through people from the Indian subcontinent who came to work in agriculture and tourism in the country’s south.

Portugal is working to step up vaccination as new cases increase exponentially. Marta Temido, health minister, has warned the daily case number is likely to double over the next two weeks, and doctors say growing pressure on Lisbon hospitals could lead to a reduction in the number of intensive care beds available to non-Covid-19 patients.