Interim guidance issued on pregnant women and swine flu
If your practice includes care of pregnant women, be sure to review just-issued interim guidance from the Centers for Disease Control and Prevention (CDC) in regard to swine influenza A (H1N1) virus infection. Epidemiologists are now tracking several reports of human infection, following cases identified in April 2009 in the United States and Mexico.
While officials say there are insufficient data to determine who might be at increased risk for complications from the infection, they point to an instance in 1988, where a previously healthy pregnant woman was hospitalized for pneumonia and died eight days later after infection with another variant of swine influenza virus. Observations from previous pandemics and findings from studies among pregnant women who had seasonal influenza indicate that influenza might be more severe in pregnant women, says the CDC in an interim guidance issued April 28.1 (Editor's note: To access a copy of the guidance, go to www.cdc.gov. Under "2009 Flu Info," select "U.S. Info." At the "Swine Flu" page, select "Guidance for Professionals," then "Pregnant Women: Considerations for Clinicians.")
"An excess of influenza-associated deaths among pregnant women were reported during the pandemics of 1918-1919 and 1957-1958," notes the CDC guidance. "Adverse pregnancy outcomes have been reported following previous influenza pandemics, with increased rates of spontaneous abortion and preterm birth reported, especially among women with pneumonia."
Pregnancy increases the risk for influenza complications for the mother and might increase the risk for adverse perinatal outcomes or delivery complications, based on case reports and epidemiologic studies conducted during interpandemic periods, the agency notes.
What should clinicians look for when it comes to swine influenza infection? Look for typical acute respiratory illness symptoms, such as cough, sore throat, rhinorrhea, as well as fever or feverishness. Many pregnant women will go on to have a typical course of uncomplicated influenza, says the CDC guidance. However, for some pregnant women, the illness might progress rapidly and might be complicated by secondary bacterial infections, including pneumonia. Fetal distress associated with severe maternal illness can occur in such instances.
The CDC advises that pregnant women who have suspected swine influenza A (H1N1) virus infection should be tested. Specimens from women who have unsubtypeable influenza A virus infections should be sent to the state public health laboratory for additional testing to identify the virus. [Editor's note: Get the interim guidance on specimen collection by visiting the "Health Professionals" web page listed earlier. Select "Interim Guidance on Specimen Collection and Processing for Patients with Suspected Swine Influenza A (H1N1) Virus Infection."]
Clinicians who care for pregnant women who meet current case definitions for confirmed, probable, or suspected swine influenza A (H1N1) infection should look at the antiviral medications zanamivir and oseltamivir, the CDC advises. The strain is sensitive to the two neuraminidase inhibitor antiviral medications, but it is resistant to the adamantane antiviral medications amantadine and rimantadine, it states. Those pregnant women who meet the current case definitions should receive empiric antiviral treatment, the agency guidance states.
"Pregnant women who are close contacts with persons with suspected, probable, or confirmed cases of swine influenza A (H1N1) should receive antiviral chemoprophylaxis," the guidance states. "These recommendations for treatment and chemoprophylaxis are the same ones used for others who are at higher risk of complications from influenza."
Antiviral treatment with zanamivir or oseltamivir should be initiated as soon as possible after the onset of symptoms. Benefits should be expected to be greatest if started within 48 hours of onset, study findings suggest. Recommended duration of treatment is five days, while chemoprophylaxis duration is 10 days. The oseltamivir and zanamivir treatment and chemoprophylaxis regimens recommended for pregnant women are the same as those listed for adults who have seasonal influenza, the guidance notes. Recommendations for use of antivirals for pregnant women might change as additional data become available.
Pregnancy should not be considered a contraindication to oseltamivir or zanamivir use, the CDC advises. Pregnant women might be at higher risk for severe complications from swine influenza. The benefits of treatment or chemoprophylaxis with those drugs are likely outweighing the theoretical risks of antiviral use, it notes.
Oseltamivir, with its systemic activity, is preferred for treatment of pregnant women, the CDC guidance states. The drug of choice for prophylaxis is less clear, the guidance reports.
"Zanamivir may be preferable because of its limited systemic absorption; however, respiratory complications and medication delivery system challenges that may be associated with zanamivir because of its inhaled route of administration need to be considered, especially in women at risk for respiratory problems," the guidance states.
Reference
- Centers for Disease Control and Prevention. Interim Guidance — Pregnant Women and Swine Influenza: Considerations for Clinicians. April 28, 2009. Accessed at www.cdc.gov/swineflu/clinician_pregnant.htm.
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