Dr. Neil Handelman is 75. He’s dealt with some of the worst scourges known to humans — tuberculosis, cancer, viral hepatitis. But he’s never seen COVID-19, and now at a time when he could be kicking back with a good book, he’s being told his age group is dangerously susceptible to this nation-rattling disease. He should lie low and stay away from everyone, the advice goes.

His response? Handelman has come out of semi-retirement and is cranking out 12-hour shifts working with patients from his home office in San Rafael.

“I don’t think of it as patriotic,” said Handelman, who works with Heal, a national home-visit and tele-health organization. “It is, I suppose, but really, I view this work now the same way as I did before — it’s about taking care of patients. I feel this is humanitarian. That’s the reason we doctors do it to begin with. We want to help people.”

He’s got a lot of company from his age group on the medical front lines these days. And it’s growing.

The California Medical Association, Gov. Gavin Newsom and the Pentagon have called for retired physicians to help, particularly for the coming surge of coronavirus cases, and they are answering in droves. The state Health and Human Services Agency and most major hospitals report being swamped with calls from doctors — and nurses — who are retired and offering to pitch in. They’re also seeing those who are still on the job and in the highly vulnerable age range of 65-plus sticking with the already growing workload of COVID-19 patients.

That approaching surge of cases is expected by health professionals to be huge in the next few weeks. Newsom estimates the state will have to add 50,000 hospital beds for the crisis. And with a national shortage of masks and other protective medical gear, nurses in particular have been protesting that they feel endangered when they tend to COVID-19 patients. But those on the front lines are still showing up, and the retired ones are still volunteering.

“The attitude for most nurses, regardless of age, is they know they can do the job. We know how to keep diseases from spreading — it’s our work all the time, already,” said Deborah Burger, 69, a registered nurse. “And we are incredibly dedicated.”

Burger works at Kaiser Permanente. But she is also president of the California Nurses Association, and she’s been leading calls for better protections for her colleagues around the state as the number of coronavirus cases mount daily, reaching about 2,000 by Monday in the Bay Area.

“When this crisis started, I thought, ‘OK, we can deal with all of this,’” Burger said. “But I’ve been a nurse for 45 years, and I’ve never seen anything like this. We’re upset that all the PPE (personal protective equipment) is kept under lock and key by managers, that we’re told to reuse our masks. Think about it: A lot of what we do is hands-on care. We clean wounds, we tend to their intimate bodily functions. We need the proper resources and supplies to protect the nurses, the patients and their families and the community.”

Still, none of that stops her from showing up.

“I’m a bit torn, yes, because I know people like me who are over 65 are more vulnerable,” she said. “But as long as I’m employed at Kaiser, I feel I should take my turn just as much as anyone else. It’s a personal decision for everyone. But people should understand that nurses, regardless of age or chronic conditions, are willing to do the work.”

That can-do attitude is reflected at the other major hospitals around the region, from John Muir Hospital in Walnut Creek to San Francisco General Hospital.

“We have quite a few doctors here who are older, they’ve been through many crises in their times — and they understand how important it is to be here in emergencies like this,” said Brent Andrew, a spokesman for San Francisco General Hospital. “And frankly, they wouldn’t want to be anywhere else because this is a time when they’re needed and they know it.

“We’re also getting retired people calling, and right now we’re not cycling them in. But who knows?” he said. “We just don’t know what is ahead and what we might need.”

The California Medical Association has logged calls from “hundreds of physicians reaching out to help,” and that includes not only retired doctors but those who have closed their practices in the economic crisis as non-COVID-19 patients have trimmed back on their visits, said spokesman Anthony York.

According to the Medical Board of California, the state has 27,974 active physicians who are 65 or older, and 2,442 who are retired. The nurses union says there are 44,530 registered nurses with active licenses in California who are at least 65. But the union did not have retirement figures.

The state was short of doctors before the pandemic hit, “and now we will need everyone we can get,” York said. “Doctors, especially older ones, are literally putting their own health at risk — physical, mental, financial — at this time. But that’s just what they do.”

He said reports from places like New York, where COVID-19 cases have overwhelmed hospitals, are unnerving. “It’s World War I-esque,” he said. “And the surreal part is now, when you know it hasn’t really hit yet. But you know it’s coming.”

York said that given the extra danger for older people, “We’re looking for other ways retired physicians can serve without running directly into the burning building, so to speak.” One of those ways is by creating a program for retired doctors to coach younger ones, “which can maybe not expose them as much to the virus.”

Another technique is telemedicine, or treating patients via video links. And that’s what Dr. Handelman is trying to stick to these days, to reduce virus exposure. The same goes for Dr. Mary Jones, 72-year-old medical director of the Rett program at UCSF Benioff Children’s Hospital.

“I would have no qualms going into the office, but I take care of my granddaughter who is 2, and her other two caregivers — her other grandparents — are over 80,” Jones said.

The worry is that Jones could bring home the virus. So for now she’s doing screen-to-screen time with patients from nine states who depend on her program, which is a vital resource for children with Rett syndrome, a genetic neurological disorder that leads to severe impairments in the ability to speak, eat, walk and breathe easily.

Both she and Handelman said they find their patients like the video technique not only because it helps them avoid traveling to a medical office, but because they also get to spend a little more time with their doctors. And it’s safer for everyone.

“This is something I never thought about before — this idea of not going in because of something like this coronavirus,” Jones said. “But I don’t notice other older doctors backing away from the work either. We’re just adjusting. We have to. I did not consider stopping working even for one minute.”

Kevin Fagan is a San Francisco Chronicle staff writer. Email: kfagan@sfchronicle.com Twitter: @KevinChron