Flu cases among young pregnant women surged at a large public hospital, calling attention to yet another group at serious risk of the flu. About 80 expectant mothers have been diagnosed with the flu since early October, and more than 60 were treated for a time in the intensive care unit at Parkland Health and Hospital System, said Dr. Jeanne Sheffield, a maternal and fetal medicine specialist.
Pregnancy weakens a woman’s immune system, making her more vulnerable to the virus. Only two of the women had the flu shot, and they had it just before they became ill, so they were not protected.
But Sheffield said it is rare to see so many pregnant women get sick. Most were in their teens and early 20s; all recovered and are out of the hospital.
“Maybe we may have admitted five or 10 a year in the past,” Sheffield said. “This is much different than normal.”
It isn’t clear why Parkland had so many flu cases among pregnant women. Some health officials speculate that it’s because Parkland - with 15,000 births annually among the leading hospitals for deliveries - is a large public hospital that treats many uninsured people. Its patients are less likely to see a doctor regularly or early in an illness, Sheffield said.
A Texas Department of Health survey found no other serious outbreaks among pregnant women in the state, and the Centers for Disease Control and Prevention has not heard of any similar outbreaks in the nation.
Sheffield believes Parkland also is being more aggressive about testing for the flu than other hospitals. Testing was done on all pregnant women who showed flu symptoms after one sick woman with an unusually high heart rate was diagnosed with it in October.
"Suddenly all of us were very aware that influenza was around, and it was affecting our pregnant women,” she said. “We jumped on it very, very quickly.”
Among the states with major flu outbreaks, Texas was the first where the virus was widespread. That may explain why Dallas is the first to report such a high number of ill pregnant women, said Dr. Tim Uyeki, a CDC epidemiologist.
“Any type of infection can lead to pre-term labor,” Sheffield said, adding that the flu can progress to more dangerous infections such as pneumonia or meningitis.
While flu shots are encouraged for everyone, women in their second and third trimesters are among those at high risk, along with women at any stage of pregnancy who are HIV-positive.
Parkland began a vaccination campaign among pregnant women when doctors noticed the upswing in cases, Sheffield said, and free shots are offered to all pregnant women treated at the hospital or any of its community clinics.
The number of flu cases began to taper off last week, the doctor said.
Search for more vaccine
Meanwhile, government officials said Tuesday they are searching for alternative supplies of influenza vaccine and monitoring whether shortages are putting patients in danger.
“We know that some areas of the country are particularly hard hit with influenza and it has been a difficult and frightening thing for many people, particularly in the context of reports of vaccine shortages,” Dr. Julie Gerberding, director of the CDC, told a news conference.
For example, supplies of flu shots at Georgia’s public health clinics are running low, though the vaccine still may be available with private providers, state health officials said.
“We are starting to run out,” said Richard Quartarone, spokesman for the Georgia Division of Public Health. “What we have we have. Some districts have a little more than others.”
Health districts in Cobb and DeKalb counties have started to reserve remaining supplies for the elderly, infants between 6 months and 23 months and those with compromised immune systems.
CDC's Gerberding said the two companies that make the flu vaccine thought they made enough, but did not anticipate that the flu season would start earlier and include a more severe strain than seen last year.
“We have a gap between what we wish we have and what we have,” Gerberding said. “We are trying to get vaccine to the people who who need it most.”
Drug maker Chiron Corp. said Tuesday it is working with the U.S. government to help boost flu vaccine supplies for this year after raising production of its own vaccine by about 50 percent versus last season. The company also said it was assessing the possibility of using extra production material to supply an additional 400,000 doses of its vaccine.
The vaccine was formulated last year and includes a mix of the three most common strains at the end of the season in February. The Fujian strain now causing severe disease was around, but manufacturers had trouble getting it into the vaccine mix, Gerberding said.
“Viruses are finicky. They don’t always grow well in eggs,” she said. The vaccine is made using chicken eggs.
So the manufacturers decided that they would leave the Fujian strain out of the mix so as not to jeopardize overall production, she said.
Increased demand for vaccine
Last year the vaccine manufacturers -- Aventis Pasteur and Chiron -- had to throw away 12 million doses because so few people bothered to get flu shots.
Gerberding said 185 million Americans fall under the guidelines for getting the flu vaccine, but only between 70 million and 75 million usually are vaccinated.
Gerberding noted, however, that the latest flu season started early and the predominant strain is the H3N2 Fujian strain, known to cause a more severe disease. These factors pushed up demand for the vaccine.
“So the trick here is what we can do as federal agency to assure the manufacturers will make more doses than we need on average,” Gerberding said.
She said Health and Human Services Secretary Tommy Thompson had asked the CDC to make recommendations, which may involve the government paying the manufacturers to make more vaccine.
The CDC meanwhile is checking who has the vaccine and who does not. The entire production had been spoken for, but Gerberding said it would take time to determine where all the doses went.
The CDC said it would closely watch flu complications among children, who have swamped hospitals in some states and surprised doctors with the severity of their illnesses.
A new concern is the rise of a common drug-resistant staph infection that is undermining efforts to treat children with the flu, an official with the CDC said Monday.
Dr. Tim Uyeki, epidemiologist with the influenza branch of CDC, said that some children have died from the staph infections -- a phenomenon the CDC has not seen before.
Flu and its complications are the sixth leading cause of death nationally among children age 4 and younger, according to the CDC.
The Associated Press and Reuters contributed to this report.