Lance Stroll on Thursday defended his decision not to undergo a coronavirus test after falling ill at the Eifel Grand Prix earlier this month.
The Canadian, who returns to action for the Racing Point team owned by his father Lawrence Stroll at this weekend's Portuguese Grand Prix, explained he had phoned his personal doctor in Switzerland, from the Nurburgring, and was told he did not have Covid-19 symptoms, but should self-isolate.
He suggested that advice had persuaded him to follow his routine and not to take any additional tests before he reached his Swiss home on Sunday evening – having missed qualifying and the race - when he returned a positive result for Covid-19.
"I went into the weekend, tested negative and had clearance to race," he told reporters.
"My next scheduled test was in the evening at the end of that weekend -- I stuck to that plan, with the conclusion from speaking to my doctor.
"I woke up Saturday morning and I had an upset stomach, which was quite bad, so I was not fit to drive Saturday morning. I took the decision to stay away from the track and spoke to my doctor.
"I had the same symptoms after Russia, a stomach issue, and I tested negative twice after the Russian Grand Prix. It was a very similar issue I had on Saturday morning, so I spoke to my doctor and he told me to self-isolate.
"He told me they were not Covid symptoms. I was not coughing, I didn't have a fever. I didn't have a head ache, I just had an upset stomach.
"I flew home the next day, on Sunday, and took my test that I always take after the race weekend and it was positive."
Racing Point team chief Otma Szafnauer had claimed Stroll missed qualifying and the race due to a stomach upset, adding that he also had some flu-like symptoms.
Stroll's team-mate Sergio Perez had tested positive for Covid-19 in July when he missed both races at Silverstone.
The Racing Point team is the only one whose drivers have been infected this season.
Asked if he should have taken a test on Saturday in Germany, Stroll said: "Hindsight is a beautiful thing, for sure. At that time, I didn't think I had Covid. I had the same symptoms in Russia but tested negative twice.
"In Germany, had I guessed I had Covid I should have got tested, but like I said I spoke to my doctor and we concluded that it wasn't Covid."
Szafnauer said earlier Thursday that Formula One had further tightened up its strict testing protocol and introduced another test to be taken by all involved in the travelling circus during the race weekend.