Swine flu has been hitting pregnant women unusually hard, so they are likely to be among the first group advised to get a new swine flu shot this fall.
Pregnant women account for 6 percent of U.S. swine flu deaths since the pandemic began in April, even though they make up just 1 percent of the U.S. population.
On Wednesday a federal vaccine advisory panel is meeting to take up the question of who should be first to get swine flu shots when there aren't enough for everyone. At the top of the list are health care workers, who would be crucial to society during a bad pandemic.
But pregnant women may be near the top of the list because they have suffered and died from swine flu at disproportionately high rates.
"Are they more at risk for severe disease? That's the issue," and it appears they are, said Dr. Denise Jamieson, an epidemiologist with the U.S. Centers for Disease Control and Prevention.
Pregnant women's risk from swine flu has been a raging topic in Europe, following the contentious suggestion this month by British and Swiss health officials that women should consider delaying pregnancy if they can.
Most health officials call that advice unwarranted — since pandemics can last more than one year — but have agreed that the health risks are significant. In a recent report, World Health Organization experts found that pregnant women appear to be "at increased risk for severe disease, potentially resulting in spontaneous abortion and/or death, especially during the second and third trimesters of pregnancy."
However, so far, WHO has not recommended that pregnant women get priority vaccinations.
Now doctors are waiting to see what's decided by the Advisory Committee on Immunization Practices, whose guidance usually is accepted by the CDC and influences doctors and U.S. insurance coverage.
Immunity may be passed to child
For more than a decade, the committee has recommended that pregnant women get vaccinated for seasonal flu, which is considered a serious threat even to pregnant women who are young and healthy. Pregnant women are unusually vulnerable — especially in the third trimester — due to changes in the lungs and immune system that make it harder for them to shake off respiratory infections, said Dr. Kevin Ault, an Emory University obstetrician.
CDC data indicate swine flu is at least as dangerous. Of 302 U.S. deaths attributed to swine flu to date, the CDC has detailed information on 266 of them. The agency has found that 15 of the 266 were pregnant women — or about 6 percent.
The first American with swine flu to die was a pregnant woman in Texas. Judy Trunnell, 33, died May 5 after slipping into a coma and giving birth to a healthy baby girl, delivered by Cesarean section.
Some infected pregnant women have other health problems. Trunnell, for example, also had asthma. But many of the pregnant women who died were considered relatively healthy, suggesting pregnancy itself is a significant risk, Jamieson said.
"I think the whole concept that this flu only affects pregnant women with underlying medical conditions is incorrect," Jamieson said.
Experts believe an effective vaccine would benefit not only a pregnant woman but also her unborn child.
Infants, whose immune systems are weak, should not get a flu shot until they are at least 6 months old. So whatever immunity they have is passed on to them by their mothers, doctors say.
The belief in the protective powers of a mother's vaccination on their unborn children was demonstrated in a study of women in Bangladesh published last year in the New England Journal of Medicine. It found that flu shots given to pregnant women reduced flu in infants by 63 percent.
Only about 15 percent of pregnant women get seasonal flu shots, experts noted, so it's not clear how many will get the new shot.
Some women avoid regular flu shots, worried about possible risks to the fetus, but studies have not shown any increased dangers from the shot.
Until recently, many obstetricians haven't offered them, choosing to avoid the expense of buying and storing vaccine and the hassle of trying to convince reluctant patients, said Dr. William Schaffner, a Vanderbilt University flu expert.
"Obstetricians are only now getting with the program and are growing comfortable with administering flu vaccine," he said.
Not a ‘major concern’ yet
It's not clear that the demand for swine flu shots would be much greater. Pregnant patients haven't expressed much concern about swine flu, said the CDC's Jamieson, who is also an obstetrician seeing inner-city patients at Atlanta's Grady Memorial Hospital.
"It hasn't been a major concern," viewed as a relatively mild illness. They worry more about economic concerns — "how to take care of the baby, how to get food to eat and how to get safe and secure housing," Jamieson said.
So far, swine flu has likely infected more than 1 million Americans, the CDC believes, with at least 300 deaths.
The United States expects to begin testing swine flu vaccines on some volunteers in August, and predicts 160 million doses may be ready by October.
As countries scramble to develop a vaccine to stop the virus, Japan found a third case of Tamiflu-resistant swine flu in a man who had taken the drug to prevent infection, the Tokushima prefectural office said Tuesday.
Just six cases of Tamiflu-resistant swine flu have been reported worldwide.
In a statement, the prefectural health department said the man in his 30s was given Tamiflu after his colleague was infected with the virus this month.
The Tamiflu-resistant strain does not appear to have spread beyond the man, who has recovered, the prefectural health department said.
Preventive use of Tamiflu has occasionally given rise to resistant viruses, including those of seasonal flu.
Denmark, Hong Kong and Canada also have reported one case each of Tamiflu-resistant swine flu.