Vunipola will not be involved in Saturday's Six Nations game against Wales after travelling through Hong Kong at the weekend.

But he has continued to train with club Saracens as he is symptom free.

"Our medical team looks at our team environment, not other people's," Borthwick told BBC Radio 5 Live.

"And that's the advice we followed. We are a camp-based environment and we stay in together 24 hours a day effectively.

"Mako didn't come into camp on the advice of our medical team, who looked into the situation closely and as a precaution they advised us that the best thing for our environment was for him not to come in.

"Mako is not ill, he is not in self-isolation, but the advice we got for our environment from our medical team and the relevant parties they consulted was that he should not come into camp, and that's the advice we followed."

Ireland's game against Italy has been postponed because of the virus, but Six Nations organisers said on Monday the rest of the weekend's fixtures would go ahead.

Lock Maro Itoje, 25, admitted the coronavirus situation in general was "a little bit weird" but said the outbreak has not distracted England from the task at hand.

"The focus has fully been on Wales," he added. "This is Test match week. We can control what we can control in front of us.

"Wales are a top team. Any team they play against, they always put teams under pressure. I'm sure they're going to come to Twickenham looking for a win.

"They're an extremely passionate group of people so it's going to be a good test for us."

'I have other things to focus on' - Marler

Joe Marler started England's victory against Ireland in place of Vunipola, who had travelled to Tonga for family reasons.

And when asked how he felt about his fellow forward's absence and coronavirus uncertainty, Marler was typically candid in his response.

"We haven't really made a lot of it," he said. "We asked 'where's Mako?', got the answer and moved on. I guess they are taking all the precautionary measures we have to do.

"There are other things I have got to focus on. I have bills I am currently late on. My son has parents' evening next week and I am trying to work out how to get around that.

"We have been given the advice of washing our hands for at least twice the Happy Birthday song, which our prime minster has recommended. So I am doing that several times a day, as well as using hand sanitiser, which is rocketing in price."