The first of the three Grand Tours, the Giro d’Italia, has been postponed due to the coronavirus pandemic and the Tour de France, which starts on June 27, is likely to be affected too.
The Vuelta starts in the Netherlands on August 14 and finishes in Madrid on September 6.
“It's a new set of circumstances," Guillen told Spanish news agency EFE.
"But the whole Vuelta team is working with motivation, and with the idea that the Vuelta will go ahead.
“We have to be prepared. For that reason, I'm transmitting excitement and motivation in these difficult times, and I can assure you that we are all more coordinated and united than ever. We want to put on a great Vuelta 2020 – the best in history.”
More than 3,000 people have died in Spain from the coronavirus and the country is currently on lockdown.
“I'm worried by everything that's happening, but above all from a human point of view," added Guillen.
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"It's an exceptional, unheard of, unprecedented situation. From here, I'm trying to comply with the established measures, which are necessary, and I'm using work as therapy.
“We're discovering new things, such as videoconferencing technology, and we're working with a new ideas committee with motivation and imagination.”