The left-arm spinner is feeling healthy and fit now.
The left-arm spinner had returned home from South Africa in January after struggling to recover from sepsis (immune system's over reaction to infection). He also contracted flu before the Test series opener in Centurion.
"I guess we'll never know. If you had those symptoms I had in South Africa now, you'd say this is definitely coronavirus. But I feel healthy and fit, and I want to stay that way as much as possible," Leach was quoted as saying by PTI on Sunday (June 28).
After a lengthy COVID-19 hiatus, the international cricket is set to return with the England-West Indies Test series from July 8.
Leach one of the five spinners selected in England's squad for the three-Test series which also features Dom Bess, Moeen Ali, and newcomers Amar Virdi and Matt Parkinson.
The 29-year-old feels he can cut through the competition and is looking to take inspiration from his batting performance at Headingley last year.
"I probably overthink at times, and that's a mental thing that I've been working hard on. In my best moments, there hasn't been a lot going through my mind. I think back to when I was out there with Stokes, and how focused I felt," he said.
"It was a simple focus on what I was trying to do, and I want to apply that to my bowling as well - find that headspace where I can give my absolute best...if I keep getting remembered for batting innings, I'll take that because I'll be doing something right if I'm playing a lot."
Jack Leach’s participation in the upcoming series has raised some questions as he has suffered multiple health issues and his immune system is not the best. But he is feeling much safer in the bio-secure environment in Southampton.
"The medication that I'm on puts me a little bit of a higher risk, but actually what I came through in the winter suggests that I can fight things off quite well. The fact that I am fit, and reasonably healthy apart from that, gives me a good chance as well," Leach said.
"I've been doing everything I need to do to stick by the rules, as has everyone else around me, but I'm not too nervous. I feel safe here in a bio-secure environment."
(With PTI inputs)