Clue: no carrots (health pass) nor sticks (mandatory vaccination) needed.
Whether it's the carrot of a COVID health pass or the stick of making vaccines mandatory for certain groups of society, many European countries have had to intervene to boost take-up of the jabs.
Except in Spain, where there are no passes nor government orders. Yet the country boasts one of the highest vaccination rates in the European Union.
More than 71% of Spain's total population of 47 million is fully vaccinated, ahead of Italy's 61%, and France and Germany on 60%, according to Our World in Data.
"Compared to the other four most populated countries in the EU, Spain holds the first place in all the indicators, also placing us in the first position of G20 countries both in first-doses injections and in full vaccination," Spain's health ministry bragged.
It hailed "a collective success that conveys a message of national pride and contributes to an unprecedented social and economic recovery".
So what are the reasons behind Spain's successful COVID-19 campaign and what can other European countries learn from it?
According to experts interviewed by Euronews, Spain's strong performance results from a combination of sound public policy and cultural factors that are deep-rooted in the country's social fabric.
But the southern European country may not be off the hook just yet.
A sluggish start after a traumatic first wave
With the EU's vaccine rollout plagued by delivery delays and logistical problems, the start of Spain's inoculation drive was sluggish.
In mid-April, when 13% of Britons were fully vaccinated, only about 7% of Spaniards were similarly protected, according to Our World in Data.
Things didn't look good at the beginning of the year when Spain kicked off its campaign, said Dr Vicente Soriano, a professor of infectious diseases and director of the UNIR Medical Center in Madrid.
"In January, after the approval of the first two vaccines in the UK, we thought that our situation was in fact very bad," the clinician told Euronews. "Everyone was aware of the disaster in nursing homes, where many people died.
"Then what happened thereafter was, I think, a robust response by the government and the autonomous communities."
Dr Soriano said Spain, along with Italy, was among the hardest-hit EU countries during the first wave of the pandemic, leading to an "over-response" to vaccination among the population.
"Needless to say that people were sensitised because they saw that in the absence of the vaccine, there was a huge collapse and saturation of the healthcare infrastructure," said Daniel López-Acuña, former WHO director of crisis management and currently an adjunct professor at the Andalusian School of Public Health. "And there was considerable mortality of close to 85,000 people. We all have lost family members. I lost my father who was 94 years old."
"In February, things changed and all the health workers became vaccinated in less than two months," Dr Soriano said, also citing the success of the vaccination campaign among police and social workers.
Then nursing homes followed suit. "Almost all the older people, more than 95% of them become vaccinated," the clinician went on.
"My hospital is one of the two largest in Madrid and I can tell you the impact was incredible. In March, before Easter, we didn't have any more admissions from nursing home residents."
A strong public health system widely trusted by the population
López-Acuña told Euronews the strength of the Spanish health system was key to the success of the country's vaccination campaign.
"At the beginning, there were some bottlenecks in terms of the availability of vaccines. This had to do with what was being received from the consolidated purchase through the European Union. But as they became steady in terms of supply, the public system worked well to deliver the vaccine," the expert said.
"The fact that Spain has a public national health service that is extended to all citizens with no intermediaries of insurances, that it's publicly owned, and is coordinated in that fashion, even though it's decentralised, makes it a very important element," López-Acuña said.
In contrast, the expert said, many European countries have a mix of public and private systems that "doesn't necessarily help" vaccine interventions.
"There has been a huge public effort, a commitment of the central government and all the regional governments to move together and forward with the vaccination," López-Acuña told Euronews.
It's not just about the performance of the public health system as such, but also its perception. Spaniards' trust in their public health institutions was a cornerstone in the country's vaccine drive, said Josep Lobera, a sociology professor at the Autonomous University of Madrid.
"We have one of the highest levels of trust in public health institutions," Lobera told Euronews.
The scholar said the reasons behind this positive perception were to be found in the country's history.
"Spain had a late transition to democracy. We did not have a democracy until 1978 and the transition to democracy ended in 1981. So in the 1980s, we were developing public health institutions, social security institutions, which is later than other countries in Europe. For many generations in Spain, especially for those who lived the transition to democracy, public health institutions are part of the modernisation of the country and they trust this institution a lot," Lobera explained.
Low vaccine hesitancy and strong solidarity values
Vaccine hesitancy has traditionally been low in Spain following "a collective trauma" dating back from the Franco era, Lobera said.
"Older generations in Spain still remember the Franco dictatorship when they didn't vaccinate against polio," the expert told Euronews.
While most countries started vaccinating against polio in the mid-1950s, Spanish authorities began their inoculation campaign almost a decade later, resulting in serious disabilities and deaths. The government recently recognised people who contracted polio at the time as victims of the regime.
Spain's confidence in vaccines in general has also benefited trust in COVID-19 jabs. According to a study by the Imperial College London published in June, 79% of people in Spain trust COVID-19 vaccines, compared to 62% in the US and 56% in France.
"Solidarity values," especially solidarity between generations, are another crucial factor in overcoming vaccine hesitancy, Lobera told Euronews.
With 55% of people aged between 25 and 29 still living with their parents in the southern European country, many young people are keen on getting vaccinated to protect their older relatives from the virus.
Tackling conspiracy theories
Spanish authorities also took a pro-active approach in tackling conspiracy theories, said Lobera, who sits on the government's vaccine strategy committee.
"We were very careful in dealing with all kinds of misinformation, like fact-checking and reacting when these thrombosis scandals with AstraZeneca in March and April were emerging."
"We were very quickly working on communicating evidence on risks and risk and benefits," he said, and "actively speaking to science journalists."
"We had very clear evidence from previous studies that politicians were influencers on complex health issues. So we recommended all politicians at all levels of the government not to discuss medical issues and let the experts discuss between them, but not make vaccination a political game field."
Neighbouring France offered a stark contrast, with President Emmanuel Macron initially telling foreign reporters that the AstraZeneca jab "was almost ineffective for 65+" before a U-turn.
Challenges still ahead
Despite its strong vaccine performance thus far, Spain cannot just yet rest on its laurels.
"The biggest challenge that we face today is that still have to vaccinate 30% of the population. We still have to vaccinate 7.8 million people to complete the vaccination coverage in all the target population," López-Acuña said.
"I think this is important not just for Spain, but for Europe. We do not reach group or herd immunity with 70% of the population vaccinated. Herd immunity in the case of COVID-19 is a mirage. We cannot reach it either with 70, 80, or 90%, because we do not have vaccines that are protecting against infection and contagion. They protect against severe disease and mortality and that is very good, but it's not what produces herd immunity, because we have huge mutations of the virus with multiple variants that escape the vaccine."
"We cannot stop at 70%," he insisted.
López-Acuña noted that while the incidence in Spain was down, it remained at quite a high level, a bit above 200 cases per 100,000 inhabitants. In this context, he warned against alleviating pandemic restrictions too quickly.
"This applies to the rest of Europe, this temptation to loosen up restrictive measures because we think that with the vaccination, we can permit ourselves to do it," he said.
Learning the lessons
Reflecting on what other European countries could learn from the Spanish experience, López-Acuña said: "What is very important is that governments take full responsibility of the vaccination campaign and carry it out and don't put themselves in an observer seat."
Governments have to "drive the issues through the mechanisms that the health systems have -- in Spain, that happened to be a national health system that is regionally administered. But in other countries, it has to do with private practitioners, with public insurance or public-private insurance. That sometimes requires extra measures of governance to ensure that the public health policies are carried out," the expert told Euronews.
"You need to make of the vaccination a total national priority, put all the resources of at the disposal of vaccination and actively reach out the population" rather than "wait for the people to come," he went on.
López-Acuña expressed the opinion that while Spain did not need vaccine mandates nor health passes due to low vaccine hesitancy, "the mandatory approach is necessary when there is a reluctance to comply with the vaccine."
"We were trying to avoid these debates," said Lobera. "And that helped us. If we were having these debates, this would foster anti-vaccination groups. These groups are going to have more influence, and more people are going to refuse vaccination."
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