Nico Hulkenberg is travelling to Barcelona this week.
But team boss Otmar Szafnauer is now "99 percent" sure that Perez will be virus-free for this weekend in Spain.
However, Hulkenberg told RTL: "I'll prepare for Barcelona in the simulator, and then go there on Wednesday or Thursday.
"Then I'll wait for good news - or for the end."
Former Renault driver Hulkenberg, who lost his full-time place in F1 at the end of last year, was hailed after qualifying third at Silverstone - but then he finished seventh.
"It wasn't the fairytale that everyone wanted in the end, but that was maybe a bit presumptuous when you see how strong Mercedes and Red Bull are.
"It was good," he insisted.
However, it might not be good enough to secure him a return to F1 next year.
"I fear that will be the case," Ralf Schumacher told Sky Deutschland.
"On the one hand, in the past he didn't look so good against some teammates, like Daniel Ricciardo. And there are very strong young drivers coming up. Sebastian (Vettel) still exists too," said the former F1 driver.
"It could well be that someone will snatch a good place from him yet again," Schumacher said. "Haas will be interested, but then there's the question of whether he wants to go there."