Raab stood in for Johnson as for almost a month while the prime minister recovered.
Johnson first became ill with the coronavirus in late March and ended up in intensive care at one point.
Johnson's fiancée Carrie Symonds was pregnant with their son at the time.
DOMINIC RAAB: And then coronavirus struck. It shook the world. It hit us hard, taking lives on a tragic scale. Every community scarred. Every one of us affected. It nearly took the life of our prime minister, our friend, as well as our leader. And you know, I get asked a lot how I felt when I was covering for him.
Well, I really worried that we might lose him. And I worried for Carrie, pregnant with baby Wilf. But I always had the faith that with the outstanding NHS care he received and his fighting spirit, that he'd pull through. Of course, there'll be lessons to be learnt from this unprecedented global pandemic, but the greatest lesson lies in the challenges we can overcome, the scale of what we can achieve when we in this country all come together.