A European country that's managed to lift many of its restrictions without suffering a huge outbreak of COVID-19 - yet - is being held up as proof herd immunity against Delta might be possible.
Twice as infectious as the original strain, experts to date have suggested it could take vaccination rates as high as 97 percent to achieve herd immunity - where outbreaks are kept in check by a lack of vulnerable new hosts for the virus to infect.
A new article published this week in The Lancet Respiratory Medicine suggests Spain might be on the cusp of herd immunity at just 81 percent fully vaccinated.
"We still don't know the exact proportion of the population that needs to be immune to reach herd immunity for SARS-CoV-2, as we need to better understand the duration and protection of transmission generated from both vaccination and previous COVID-19 infection," Jesús Rodríguez Baño, head of infectious diseases at the Virgen de la Macarena Hospital told the journal.
"However, the situation in Spain might provide some clues: after leaving behind most of the control measures in the population, the infection rate (and particularly the hospital admission rate) has been going down, and this is the opposite of what happened in previous waves."
The data doesn't lie - a massive wave of infection in July saw an average 26,000 new reported infections a day in the country of 47 million, but it's since fallen to below 2000, despite loosening restrictions. Deaths in the July surge weren't as common as in previous waves likely thanks to the vaccine rollout and improved treatments, but still reached an average 125 a day - that's fallen to 25.
In the past month, new infections have fallen two-thirds and infections in teenagers - who are now 80 percent vaccinated - have dropped five-fold. Those under 12, who can't yet be vaccinated, are reaping the benefits too - infections a third what they were a month earlier.
"The only plausible explanation is the very high rate of vaccination in the country," said Dr Baño. According to the University of Oxford's Stringency Index, which measures how tough each countries' restrictions are, Spaniards currently enjoy more freedoms than most other Europeans (their neighbours in Portugal have them beat) and New Zealanders.
Spain was hit very hard in the first wave of COVID-19, suffering nearly 1000 deaths a day in April 2020. Subsequent waves in November 2020 and February 2021 saw tens of thousands of more die, the Mediterranean nation losing at least 87,000 people to date
While studies suggest infection with the virus doesn't provide as much protection against reinfection as the vaccines do, the sheer number of confirmed cases in the country (more than 5 million) combined with impressive vaccine coverage (in the top 10 in the world) means Spain might be in for a "much more normal" holiday season this year.
"However, we must be prudent in our predictions," said Dr Baño, warning future variants might render the current vaccines less effective at stopping transmission, even more so than Delta already has.
According to the University of Washington's Institute for Health Metrics and Evaluation, modelling shows Spain still faces a potential surge of infections in late December if mask use drops.
In the meantime however, Spaniards can now boast they're living in the second-best place in the world to be during the pandemic, according to Bloomberg's COVID Resilience Index, a position held by New Zealand as recently as June (we're now in 32nd, thanks to the tough restrictions imposed to fight our own Delta outbreak). Portugal is ranked 18th, with restrictions on travel in and out of the country holding it back.
Like New Zealand, Spain had a slow start to its vaccine rollout - but has since overtaken the likes of the UK and US, which had headstarts but have since run into hesitancy problems. New Zealand is 34th when it comes to second doses, also ahead of the UK and US, and aiming for 90 percent.
