2009 H1N1 aka Swine Flu

Pregnant women are at very high risk from the H1N1 (swine flu) virus. Here are expert answers to questions about the vaccine.


Public health experts continue to warn that the 2009 H1N1 virus (aka swine flu) has the potential to cause widespread, serious illness—even death. And because pregnant women are among those at highest risk, officials are recommending that they be at the front of the line to receive the vaccine. Clinical trials on pregnant women have been conducted, and a vaccine became available in October.

The introduction of any new vaccine can raise concerns, especially when pregnancy is involved. To help address them, here are answers to some of the most common questions about this strain of the influenza virus. For more information, including breaking news and updates, visit flu.gov.

Is the 2009 H1N1 vaccine recommended for all pregnant women?

Yes—except for women who cannot receive the regular seasonal flu vaccine because they are allergic to eggs. (Both vaccines contain a virus that is grown in eggs.) “We’re recommending that all other pregnant women get the vaccine as soon as it’s available, regardless of their stage of pregnancy,” says Anthony S. Fauci, M.D., director of the National Institute of Allergy and Infectious Diseases at the National Institutes of Health. Expectant women should not receive the nasal spray flu vaccine.

Why is it so important that pregnant women be vaccinated?

Expectant women are more susceptible to serious complications from infection with all types of influenza viruses, including the 2009 H1N1. “There is not only an increased risk of being hospitalized, but we’ve found a disproportionate number of deaths among pregnant women,” explains Denise Jamieson, M.D., MPH, a medical officer with the Centers for Disease Control and Prevention (CDC). Pregnant women comprise 1 percent of the population, yet 6 percent of deaths from H1N1 have been among pregnant women.

What should a pregnant woman do if she thinks she may have the virus?

Regardless of whether a woman has been vaccinated, she should call her doctor immediately if she experiences any symptoms, which include fever, cough, sore throat, runny or stuffy nose, body aches, headache, chills and fatigue (the same symptoms as the seasonal flu). This is also the case if she’s been exposed to anyone confirmed to have the virus. Additionally, all people who contract the disease—especially pregnant women—are urged to receive antiviral drugs within 48 hours of the onset of symptoms. “But even after 48 hours, there’s still a benefit,” Jamieson says.

How do we know the vaccine is safe?

Because the H1N1 vaccine is so similar to the seasonal flu vaccine, Fauci, who oversaw the government-sponsored trials, is confident about its safety. “Very similar vaccines made by the same companies, with similar properties, have been safely given to pregnant women to prevent seasonal flu for decades,” he says. “These vaccines have a very good safety record, with no red flags.”

Fauci adds that while there is a theoretical risk from any vaccine, the dangers of not getting vaccinated far exceed any potential ones the new vaccine may pose. Side effects most commonly associated with the seasonal flu vaccine include swelling and redness at the injection site.

Will there be enough vaccine available for everyone who wants it?

Because there was uncertainty about whether enough would be available, the CDC targeted five groups who have priority: pregnant women (they are at the head of the line); people who live with or care for children younger than 6 months of age; health care personnel with direct patient contact; children ages 6 months through 4 years; and those ages 5 through 18 years with chronic medical conditions.

Does the H1N1 vaccine take the place of the seasonal flu vaccine?

No. The vaccines protect against completely different viruses, and pregnant women are advised to get both.

Does either vaccine contain thimerosal?

According to the CDC, pregnant women may receive flu vaccines with or without thimerosal. While there’s no evidence that the preservative is harmful to a pregnant woman or a fetus, some moms-to-be are concerned about exposure during pregnancy. As a result, thimerosal-free seasonal and 2009 H1N1 influenza vaccines are available in single-dose units for pregnant women and small children.