In a message on Twitter, he wrote: "Thank you for all the love and support I am doing fine and am in the best hands".
He said: 'We could have folded and disappeared.
"Their retention of the ball was top class".
Playing bravely out from the back rather than clearing long, England worked the ball to Kane who found the marauding Shaw on the left and his precise pass was ideal for Rashford to slot past his Manchester United team mate David De Gea.
"We tried to press and play with high intensity".
Shaw, who revealed this week he came close to losing his leg after a serious break suffered while playing for United against PSV in 2015, was making his first global appearance for 18 months.More news: Democrats threaten to leak documents on Kavanaugh's hidden views
Rashford so almost levelled with a powerful header that De Gea clawed away from his goal while Jordan Pickford comfortable kept out Saul after another sweeping move forward.
The referee gave nine minutes of injury time following the delay for Shaw's injury and substitute Danny Welbeck looked to have scored the equaliser from close range, but was harshly whistled for a foul on De Gea as he jumped for a loose ball in front of his net.
It was a packed 90 minutes for England's opening Nations League match, with games against Spain and Croatia - both home and away - yet to come. However, the strike was ruled out for a foul on De Gea as Spain hung on to claim three points.
"We have one of the best goalkeepers in the world, he's showed that for many years in the Premier League". We are a different profile of players who can't play like they do.
England then suffered a blow at the start of the second half as Shaw had to be stretchered off after a collision with Dani Carvajal.
The impact was audible from the stands and led to him leaving on a stretcher wearing an oxygen mask and a neck brace after lengthy treatment.