Returning to Fox Business, Neil Cavuto credits vaccination with saving his life.

Neil Cavuto, the veteran Fox Business host who has not appeared on the network for over a month, returned on Monday, telling viewers that his absence was because of Covid-19 pneumonia that sent him to an intensive-care unit “for quite a while.”

“It really was touch and go,” Mr. Cavuto said on his show “Cavuto: Coast to Coast” on Monday, adding, “Doctors say had I not been vaccinated at all, I wouldn’t be here.”

Mr. Cavuto said this recent infection was “far, far more serious” than the one he got last year.

Mr. Cavuto, who hosts about 17 hours of television every week with three different shows, has been among Fox’s most vocal proponents of vaccination, and on Monday he sought to dispel misinformation about his recent illness.

“No, the vaccine didn’t cause that,” he said of his extended illness. “That ‘grassy knoll’ theory has come up a lot.”

“Because I’ve had cancer, and right now I have multiple sclerosis,” Mr. Cavuto continued, “I am among the vulnerable 3 percent or so of the population that cannot sustain the full benefits of a vaccine.”

Mr. Cavuto told viewers that Fox had not explained his prolonged absence — according to a Fox spokeswoman, he had not been on the network since Jan. 10 — because the network was “honoring my wishes, out of respect for my privacy.” But, he added, “this did drag on a long time for me, so you do deserve an explanation from me.”

The network has come under criticism after some of its popular hosts, including Tucker Carlson and Laura Ingraham, and their guests have falsely suggested that vaccines could be dangerous. Compared with them, Mr. Cavuto has been an outlier.

After recovering from Covid late last year, Mr. Cavuto appeared on the Fox program “Media Buzz” to discuss his experience. “I’d like to urge people of all sorts: Please get vaccinated,” Mr. Cavuto said at the time.

He received a diagnosis of cancer in the 1980s, a diagnosis of multiple sclerosis in 1997, and had heart surgery in 2016, the network reported. Because of his medical history, Mr. Cavuto said he, like “plenty of people” at Fox and another companies, “are susceptible” to Covid.

“If you can get vaccinated,” he went on to say, “and think of someone else and think of what that could mean to them and their survivability from something like this, we’ll all be better off.”