New Haven has a bad case of the flu, with symptoms including overflowing emergency rooms, stressed doctors and crowded hospital hallways.

The Yale-New Haven Hospital has seen an increase in both influenza infections and hospital admissions in the past few weeks, said Dr. Phillip Brewer, a professor of emergency medicine at the Yale School of Medicine. During the last week in January, the hospital documented 109 positive swabs for respiratory illnesses, approximately 60 of which were influenza. Over 50 of the patients with positive swabs had to be admitted to the hospital, Brewer said.

Yale-New Haven Hospital usually experiences a short period of severe crowding during the winter flu season, but this year has been worse than most, he said. These annual situations usually last for about six to eight weeks, and Brewer said the hospital is currently halfway through this year’s outbreak.

“These are very stressful times and conditions for both patients and staff,” Brewer said. “The overall hospital census tends to rise because you have more admissions and people occupying beds for greater lengths of time.”

During the winter, both the types of illnesses observed and the way in which patients are admitted to the hospital are different than during the rest of the year.

“Pretty much everybody that gets admitted to the hospital comes in through the emergency department, which is really a big problem for everybody,” Brewer said.

Crowding in the emergency department and increasing admissions lead to crowding throughout the hospital. During peak times, hospital workers are sometimes forced to shut down part of the emergency department, Brewer said, essentially turning it into an inpatient ward. Hospital administrators have numerous strategies for dealing with overcrowding, but measures tax hospital resources and often cause stress for doctors and other hospital employees.

This week Yale-New Haven hired temporary staff and increased overtime for employees in order to fully utilize vacant hospital space.

“It was challenging … but they were able to open up an additional 10 beds, which helped a lot,” Brewer said.

Overcrowding also forces hospital administrators to cancel or defer elective surgeries because of the lack of recovery space, a measure that frustrates both patients and doctors, he said. In addition, the hospital is forced to temporarily board patients in hallway beds until space in rooms becomes available.

“When we are at what we call [the] red zone [of emergency department overcrowding], the floors are required to accept overflow patients on hallway beds,” Brewer said. “If you don’t do that then the ‘out of sight, out of mind’ mentality prevails, and the floor to which a patient has been assigned really has no incentive to create an inpatient space for them.”

Brewer said one possibility for the increase in influenza cases may be the shortcomings of this year’s vaccine.

“The epidemiologists have to kind of predict what the flu strains are going to be and put that into the vaccine,” he said. “Sometimes they get it just right and sometimes not.”

This year about 25 percent of influenza cases documented by the hospital involved strains not covered by the vaccine, Brewer said.

The outbreak in New Haven reflects a statewide trend in influenza infection.

According to the Centers for Disease Control and Prevention, Connecticut was classified in the highest disease activity group last week.

Although the Yale-New Haven has observed an increasing number of influenza cases, there has not been a similar trend in the University community, said Paul Genecin, the director of Yale University Health Services.

Genecin said the number of documented cases at Yale has been relatively low despite projected vaccine shortages.

“This has been a mild year, and … we have not seen a spike in influenza in the Yale population,” he said.

The lack of a correlating influenza outbreak may be due in part to the University Health Services’ attempts to immunize certain groups within the Yale community which are most likely to contract the disease, Genecin said. These measures may have limited the impact of the flu despite this year’s immunization shortage.

“We are a little unusual in the sense that we target very specifically the at risk populations at Yale for immunizations,” he said.

Vulnerable populations include the elderly, young children, health care workers, care givers, pregnant women and individuals with illnesses that may impair the immune system and leave them especially susceptible to infectious diseases. These illnesses include diabetes, asthma, cancer and cardiovascular disease.

While immunization does not guarantee influenza prevention, it is an important precaution, Genecin said. In addition, other measures, such as frequent hand washing, are also key in terms of avoiding the disease.