Cordoba, Spain (CNN) Unseasonably warm weather, Champions League football and other major events, homes on the beach and the café culture: just a few of the factors that may have helped carry an insidious virus across southern Europe -- from country to country and city to city, from Italy to Spain and Portugal.

The virulence and lethality of the coronavirus was compounded by the fact that symptoms take at least several days to emerge -- and by a series of missteps by governments as they chased its impact, before eventually succumbing to the reality that only a total lockdown could stem the tide.

More than 5,000 people have died since a coronavirus outbreak exploded in Spain, one of the countries worst affected by the pandemic. The country has more than 54,000 active cases of the virus, according to recent figures from the ministry of health.

On February 19, nearly 3,000 Valencia football fans traveled from Spain to Milan to watch their team play Atalanta in a European Champions League game. Some 40,000 Italians were also at the game, many of them from Bergamo and surrounding towns.

Atalanta fans cheer during a Champions League match between their team and Valencia on February 19 in Milan.

Milan was buzzing that evening, according to the Mayor of Bergamo, Giorgio Gori. Besides those who attended the game, "others watched it from their homes, in families, in groups, at the bar," Gori said this week. "It is clear on that evening there was an opportunity for a strong spread of the virus."

Immunologist Francesco Le Foche is of the same view, telling the Corriere dello Sport: "It's probable that there were several major triggers and catalysts for the diffusion of the virus, but the Atalanta-Valencia game could very well have been one of them.

"With hindsight, it was madness to play with a crowd present, but at the time things weren't clear enough," Le Foche said.

Two days later, in the town of Codogno, some 60 kilometers (40 miles) from Bergamo, a 38-year-old man known as "patient one" was diagnosed with the virus. But by then, according to research reported by nearly 20 Italian specialists, the virus had long been on the move.

"At the time of detection of the first Covid-19 case, the epidemic had already spread in most municipalities of southern Lombardy," they say.

After examining nearly 6,000 confirmed cases the researchers discovered that there were already 388 patients in the Lombardy region with novel coronavirus as early as February 19 -- even if they'd not yet been identified as such.

"In the week that followed, [the] Codogno area, as well as several neighboring towns in southern Lombardy, experienced a very rapid increase in the number of detected cases," the researchers note.

Although the research has not been published in a peer-reviewed journal, it was mentioned in a report by the journal Nature on Friday.

By then the visitors from Valencia were back home. One of them was sports journalist Kike Mateu. He told CNN that four days after returning home he had a cough and difficulty breathing. A few days later, "I decided to go to the hospital because by then there was an explosion of coronavirus cases in Lombardy."

People keep their distance from each other as they wait in a supermarket queue in Barcelona on March 16.

On February 27, a health department spokesman in the Valencia region confirmed to CNN six new cases of coronavirus in the city. Three days later, a Portuguese man who had visited Valencia tested positive after returning home. Mateu passed it on to four of his co-workers, and Valencia football club would later report that more than a third of their players and coaching staff had tested positive for the virus.

In the first week of March, the Spanish health ministry ordered large sporting events to be held behind closed doors, including the return leg of the Valencia-Atalanta tie.

Rallies for But in other respects, life in Spain went on pretty much as normal. Bars and cafes were open; unseasonably warm weather brought Spaniards out into common spaces.Rallies for International Women's Day on March 8 brought tens of thousands onto the streets across Spain, including a crowd estimated at 120,000 in Madrid. Two female cabinet ministers who attended the event later tested positive for coronavirus, although it's not known how they contracted the virus. Opposition parties have criticized the government for allowing those events to go ahead.

Health workers prepare to receive the first coronavirus patients at Ifema exhibition complex in Madrid on March 22.

The following week, the government moved to what its health minister, Salvador Illa, called "reinforced containment." The main measure was to close schools and universities in Madrid from March 11. But this may not have had the intended effect.

Hundreds of thousands of students enjoyed a sudden and unexpected holiday. Many Madrilenos left the capital, perhaps anticipating stricter measures. The roads were crowded when Spanish Prime Minister Pedro Sanchez declared on March 13 that a "state of alarm" would be introduced. But its details were left to a Cabinet meeting the following day.

Even before those details were published -- essentially putting Spain on lockdown -- local authorities in places like Murcia and Valencia began to close beaches and tell people from Madrid not to visit their homes on the coast.

The following weekend, the Guardia Civil, the national police force, felt it necessary to tweet: "Do not travel to your second residence at the beach, in the mountains or in the town."

Durante el #finde estableceremos dispositivos en vías y espacios públicos para asegurar el cumplimiento de las restricciones de la circulación y se sancionará su incumplimiento#QuedateEnCasa

No viajes a tu 2ª residencia en la playa, montaña o el pueblo. pic.twitter.com/JM2RRmAUcg — Guardia Civil 🇪🇸 (@guardiacivil) March 20, 2020

The overall response seemed disjointed, complicated by familiar rivalries between the central government and the regions -- especially Catalonia.

Spain has certainly been far from alone in scrambling to keep up with the impact of coronavirus. As PM Sanchez himself has admitted, "We can understand that right now every measure seems insufficient, but just a week ago it might have seemed exaggerated.

"Limiting freedoms is something a democratic government can do only when it is absolutely necessary," he told a session of parliament. Spain is still haunted by the Franco era and his iron rule from Madrid.

On Thursday, Health Minister Salvador Illa spoke of a "phase of stabilization" in the trend of diagnoses, a hope echoed by the Director of Spain's Center for Health Emergencies Fernando Simón.

Members of the Military Emergencies Unit (UME) carry out a general disinfection at Malaga airport on March 16, 2020.

Even if true, the strain on the health service -- which Spaniards are proud of -- will continue for weeks to come. Thousands of health workers have been infected.

The cost to the economy of the lockdown -- now extended for two more weeks -- will deepen. The Spanish government is demanding more forceful action from the European Union to finance recovery

And some awkward questions will begin to be asked. The government is already being sued by a Madrid attorney for allowing the March 8 rallies to go ahead. And Kike Mateu, now recovering in Valencia, is one of many thousands of Spaniards who are angry. "Instead of isolating people, the government invited people to go out to the streets. And this is a huge irresponsibility."