In a reminder that the new strain of H1N1 influenza may be more dangerous than originally thought, federal health officials reported Thursday that 100 pregnant women infected with the virus were hospitalized in intensive care units in the first four months of the outbreak, and 28 have died.
"What we are seeing is quite striking," said Dr. Anne Schuchat, director of the National Center on Immunization and Respiratory Disease at the Centers for Disease Control and Prevention in Atlanta. She is helping direct the government's response to the pandemic.
"The obstetric caregivers here, and the ones that we're speaking with [around the country], have rarely seen this kind of thing in practice," Schuchat said at a weekly briefing. The 28 deaths occurred between the emergence of the new strain in late April and the end of August.
Until this outbreak, hospitals were not required to report to public health authorities deaths from influenza, except in children. As a consequence, the "expected" mortality of pregnant women who become ill with seasonal flu strains is not known.
"Whether this is more common or people are just noticing it because we're attending to this H1N1 virus, it's difficult to say," Schuchat said. However, she added, anecdotal reports are that "doctors around the country . . . have never seen this kind of thing before."
Most previous influenza pandemics have also had what appeared to be unusually high death rates in pregnant women.
In one series of 1,350 "Spanish flu" cases in pregnant women in 1918, 27% were fatal. In the "Asian flu" outbreak of 1957, half the women of reproductive age in Minnesota who died of the infection were pregnant.
Pregnant women are among the five "initial target groups" that public health authorities say should be offered the H1N1 vaccine when it is available.
In the briefing, Schuchat said that 600,000 doses of the nasal-spray form of the vaccine will be delivered to 25 states and cities by Tuesday. The shipments mark the start of the unprecedented effort to offer a pandemic flu shot to every American who wants one.