Members of the D.C. homeless community have constructed an encampment in front of the Central Union Mission. These crowded spaces can become breeding grounds for diseases such as the flu. (Carmen Heredia Rodriguez/KHN/Carmen Heredia Rodriguez/KHN)

The flu descended on Connie Gabaldon like a fog, she recalled, clouding her mind and compromising her judgment. It progressed to chest and back pain, the aches perhaps made worse by a fall the 66-year-old had while riding the bus in Santa Fe, N.M.

Gabaldon is homeless. When she went to the emergency room in late January, doctors told her she had pneumonia, a sinus infection and the flu.

For the healthy, the flu represents a serious health concern. But for the homeless — who deal with higher rates of chronic illness, fewer resources and crowded conditions in shelters — catching the flu can be a matter of life or death.

This year, the nation is experiencing a vicious flu season that is on track to break recent records, according to the Centers for Disease Control and Prevention. Although the outbreak has shown signs of decline over the past two weeks, it is still ongoing in 45 states and the District, thousands of people have been hospitalized and 114 children have died.

If you’re homeless, having the flu “might mean that you can’t get up and manage to stay warm. You can’t go get food. And if you have a substance abuse disorder and you need to maintain either alcohol or opioid use, then you go into withdrawal,” said Eowyn Rieke, a board member of the National Health Care for the Homeless Council.

“The gravity of the flu for people who are homeless is enormous. And I think we often underestimate that.”

Paul Martin recovers after getting a flu vaccine at a homeless shelter. (Carmen Heredia Rodriguez/KHN/Carmen Heredia Rodriguez/KHN)

Avoiding the flu is just one of many health challenges for those who are homeless. Homelessness worsens depression and cognitive function, said Margot Kushel, a professor of medicine at the Zuckerberg San Francisco General Hospital and Trauma Center.

Chronic diseases are also harder for the homeless to manage. Roughly two-thirds of the group cope with a chronic condition or a substance abuse disorder. Smoking is common. And 3 in 10 people who are chronically homeless have a serious mental illness, according to the Office of National Drug Control Policy.

William Coleman, a 51-year-old former construction worker who has struggled with cocaine addiction problems, is in counseling and anger management classes at Central Union Mission shelter, located near Washington’s Union Station. He is also accessing more preventive health care — including the flu vaccine, which he got earlier this year.

“I really want to take care of my health,” he said, the pungent smell of bleach rising beside him from the bucket and mop that he uses to clean the sleeping quarters in the shelter. “I want to live as long as possible.”

But the tight quarters at shelters make Coleman and the others vulnerable to illnesses. Crowding and poor hygiene create an environment primed for the flu to spread, said Jeff Engel, executive director of the Council of State and Territorial Epidemiologists.

Subpar conditions among the homeless have led other outbreaks in recent years. In Atlanta, a drug-resistant tuberculosis problem began in a homeless shelter in 2008 and infected more than 100 people in the city and surrounding county, according to the health department.

Last year, poor access to restrooms among the homeless community in San Diego and other parts of Southern California fueled a rash of hepatitis A cases that infected hundreds and killed 21 people, according to the state’s health department.

“You’ve got very vulnerable people, who’ve got underlying health problems, poor access to health care, poor environmental conditions, crowded together,” Kushel said. “And then you throw in a particularly nasty flu, and then you really got a recipe for disaster.”

In Washington, flu activity is two levels below the most severe “widespread” category, according to the CDC. However, the number of people who have been infected so far is the highest in five years, with 2,150 confirmed cases as of Feb. 17 . Maryland reported 23,111 laboratory-confirmed cases as of Feb. 17, and Virginia health officials said the state had 2,652 cases as of last Friday.

Deborah Chambers, senior director of strategic partnerships and community engagement at Central Union Mission, said the facility has been on alert all winter for the flu. In addition to daily cleaning of the shelter, hand sanitizers have been placed throughout the building and flu shots are offered, she said.

These efforts are partly a response to a flu outbreak last year that “ran through the whole building,” Chambers said. This year, other than a few staff members falling ill to the virus, she said, the organization has not seen a spike in the number of flu cases.

Nonetheless, the organization held a vaccine clinic Feb. 9. The CDC said this year’s vaccine is 36 percent effective overall, but only about 25 percent effective against the dominant H3N2 strain. Nevertheless, experts say it provides some protection and is worth getting, even at this late date.

Unity Health Care, a nonprofit that caters to low-income residents in Washington, also held flu clinics Jan. 25 at two shelters for the homeless. The health system had promoted the vaccine in the fall, but those events had marginal success, said Catherine Crosland, Unity’s medical director of homeless outreach services.

To try again, she and Caroline Garber, a Walgreens pharmacist, arrived at one of the shelters with a big red bag containing 50 vaccine doses. Paul Martin was their first client. “I really don’t like needles, but I do need the flu shot,” he told Garber.

A steady trickle of men made their way in to get shots. Among them was Robert Ford.

He had been unemployed and homeless for about two years, he said. He is diligent about his flu vaccines, in part because he has diabetes. He takes medication to manage it and watches his diet. By the end of the night, he was one of 26 men who got vaccinated.

Because the vaccine does not completely immunize a person from the flu, doctors say that when someone fall ill, isolation is one of the best ways to prevent the spread of the virus. But that is difficult to arrange for the homeless.

Crosland said 45 medical beds for the more than 7,700 people living without homes in the District are “definitely not” enough to meet the demand.

Moreover, these beds are not equipped to isolate a person with the flu from the rest of the population. The women’s respite beds, for instance, consist of 12 bottom bunks scattered throughout the general clients’ sleeping quarters at Patricia Handy Place for Women.

“I think we’re going to get hit,” said Janelle Goetcheus, chief medical officer for Unity Health Care, which manages medical respite beds for the homeless in the District. “It’s only a matter of time.”

In Santa Fe, shelters use medical respite beds for those sickened by the flu. At the Interfaith Community Shelter, an increasing number of clients use these accommodations to recover from the virus and upper respiratory infections, said Sue Carr, assistant to the executive director.

On doctor’s orders, Gabaldon occupied one of those beds after being released from the hospital.

After several days, she said, she’s “coming around.” But her physician authorized her to extend her stay in medical respite, for which Gabaldon is grateful.

“I still feel weak,” she said. “But thank God the doctor gave me four more days, because it’s freezing out there in the morning when they put us out.”

Heredia Rodriguez is a reporter for Kaiser Health News, a nonprofit news service covering health issues and an editorially independent program of the Kaiser Family Foundation. Heidi de Marco, a reporter and producer for California Healthline, contributed to this story.