As states begin to allow nonessential businesses such as gyms and restaurants to open their doors, many Americans will cautiously emerge from their homes after weeks of isolation.

Tayjus Surampudi, a Google employee, will not be one of them.

Surampudi, 24, works as a strategic program manager for the company's apps business, so it's been easy for him to work remotely these past few months. He expects that he'll continue to do so for the foreseeable future, regardless of any policy changes at Google or in Mountain View, California, where he lives.

That's because Surampudi has Duchenne muscular dystrophy, a genetic condition that causes progressive muscular degeneration. That makes him one of millions of Americans at high risk for complications if he contracts Covid-19.

"I have to be careful and really don't want to put myself in a situation where I could end up in the hospital," he said by phone. "I recognize that it could be a year or longer."

Surampadi is just one of about half a dozen people who told CNBC they're preparing to remain at home until there's a vaccine available, which could take 18 months or more, or until they hear from a scientific expert such as Dr. Anthony Fauci that it's safe for them to resume life as normal.

Somewhere between a third and half of Americans fall into a high-risk category when it comes to the coronavirus, suggests Dr. Ashish Jha, the director of the Harvard Global Health Institute. They include people over the age of 65, nursing home residents, and people with underlying medical conditions including heart problems, chronic lung disease or a condition that attacks their immune system.

The Centers for Disease Control and Prevention website recommends that this group stay at home as much as possible and avoid close contact with others.

But it's unclear exactly how long they should be following these guidelines. So some are proceeding with maximum caution.