All teams are being kept apart in individual "bubbles" at and away from the circuits, with then each team divided into further separate groups, in order for the impact of any positive coronavirus cases to be mitigated.
With confirmation that grands prix would not be canned in the event of a positive test teams therefore needed standbys at the ready.
Racing Point's reverse drivers are Esteban Gutierrez and Stoffel Vandoorne, the test drivers on the books of engine suppliers Mercedes.
First and foremost Perez's health is the most important aspect, and everyone wishes him a speedy and full recovery.
It left Racing Point with a choice between just two drivers.More news: Google Teases Pixel 4a Launch for 3rd August
Hulkenberg said: "I was on my way to the Nurburgring for another racing project when the call from Otmar came".
"I tried to take it step by step today, to get up to speed with the auto and understand it". And also he has relevant experience from having driven in F1 past year. "It just shows how vulnerable we all are to this".
While Gutierrez drove up from London - where he is based - Hulkenberg headed over to the United Kingdom from Germany, with his boots and helmet, landing in Birmingham at 19:00, before travelling to Racing Point's factory. A contract and Super Licence paperwork also had to be wrapped up.
"Perez has entered self-quarantine in accordance with the instructions of the relevant public health authorities, and will continue to follow the procedure mandated by those authorities", read a statement issued by Formula 1 and the FIA. It just takes time to inhale everything, understand it, know how you have to drive it and learn.
F1's managing director Ross Brawn warned at the Styrian Grand Prix that the championship could not afford to get complacent over its hygiene protocols and stressed a positive test result was likely at some stage.More news: Lou Williams shares surprising reason why he likes Magic City strip club
He will miss at least the two races at Silverstone this weekend and next.
After finishing ninth in opening practice, Hulkenberg improved to seventh, but remained six-tenths off the pace set by Racing Point team-mate Lance Stroll who topped the times in FP2.
"But the reason for it is there is a bit of uncertainty, and we're still not sure if it is seven or 10 days".More news: UK's Johnson hits the brakes after 'warning light' of spike in cases