When administered to pregnant women, the influenza vaccine can prevent flu-related infant hospitalization, research efforts led by Yale School of Medicine professor Marietta Vázquez ’90 showed in late October.

Because vaccines are not typically licensed for children under 6 months old, Vázquez said, researchers have to find alternative methods to protect them from the flu.

“Young children often have very high hospitalization rates [for the flu],” Vázquez said.

The immune response of pregnant women is weaker than normal, so they are more susceptible to the flu and possible complications, Louise Dembry, the director of hospital epidemiology at Yale-New Haven Hospital, said.

Vázquez’s team studied data from 350 children who were hospitalized at Yale-New Haven from 2000-’09. Children up to 12 months old who were hospitalized due to the flu were compared to a control group of children of the same age who were hospitalized because of other illnesses, Vázquez said.

The researchers then checked to see whether the infants’ mothers had been vaccinated during pregnancy, Vázquez said. The researchers found that the flu vaccine, when given to expectant women, was 89 percent effective in preventing children up to 6 months old from being hospitalized due to influenza.

Vázquez said the new findings are significant for three main reasons.

“First and most importantly, this is a way to protect the young,” Vázquez said. “Second, it is cost-effective because it protects two individuals, the mother and her child. And third, we hope this data will help the vaccination program for pregnant women to move forward.”

Vázquez and her team presented their findings at the 47th annual meeting of the Infectious Diseases Society of America, which was held Oct. 30 in Philadelphia. The Infectious Diseases Society of America is the largest national organization for both pediatric and adult infectious disease specialists, Vázquez said.

The annual battle against the flu has been complicated by the outbreak of the H1N1 flu this year. New Haven has had a shortage of both seasonal flu vaccines and swine flu vaccines this year, Dembry said. The H1N1 vaccine, which comes from the state government, has only been sent to certain health care providers, she added.

Yale-New Haven sent in a request over the past summer for 18,000 doses of the swine flu vaccine, Dembry said. But the hospital had received only 500 doses as of last week, she added. Yale University Health Services has received about 700 doses, which were prioritized for children ages 2 to 5 and pregnant women, YUHS Director Paul Genecin said in late October.

But there are still opportunities to get vaccinated for the seasonal flu, New Haven Health Department Director William Quinn SPH ’75 said. The New Haven Health Department is holding an open clinic at its main office from 9 a.m. to 12 p.m. Tuesdays until Nov. 24. Quinn encouraged high-risk groups such as emergency care providers and pregnant women to come to the clinic.

Although the seasonal flu vaccine is in very high demand, Quinn said, he added that he is optimistic the Health Department will not run out before next week’s clinic.

“It looks like we will make it though this week and have enough vaccine for next Tuesday,” he said.

President Barack Obama declared the swine flu outbreak a national emergency on Oct. 24.