Antiviral treatment might still be beneficial in patients with severe, complicated or progressive illness and in hospitalized patients when given after 48 hours of illness onset. For example, antiviral treatment of pregnant women (of any trimester) with influenza A (2009 H1N1) has been shown to be most beneficial in preventing respiratory failure and death when started within 3 days of illness onset but still provided benefit when started 3– 4 days after onset compared to 5 or more days. A larger study reported similar findings and showed that starting oseltamivir treatment up to 4 days after illness onset provided benefit in reducing the risk of severe illness compared to later treatment of 2009 H1N1.

Dosing:

• Oseltamivir: 75 mg BID X 5 days for acute infection; Q day X 10 days for prophylaxis
• Zanamivir: Two 5-mg inhalations (10 mg total) BID X 5 days for acute infection; Q day X 10 days for prophylaxis

Risks in Pregnancy: During previous influenza epidemics and pandemics, pregnant women have appeared to suffer higher influenza-associated morbidity and mortality compared with women who are not pregnant. This is thought to be related to several physiologic changes that occur during pregnancy, including alterations in the cardiovascular, respiratory, and immune systems.

Pneumonia: Influenza can lead to a primary viral pneumonia with potential for a secondary bacterial pneumonia. Incidence has been reported in 12% of influenza infected pregnant women. Primary influenza pneumonia does not respond well to antiviral therapy, and mortality remains high. Consider admission of all pregnant patients with respiratory symptoms as well as confirmed pneumonia.

H1N1: Pregnant women who were otherwise healthy were severely affected by the 2009 H1N1 influenza A virus (formerly called “novel H1N1 flu” or “swine flu”). In comparison to the general population, a greater proportion of pregnant women infected with the 2009 H1N1 influenza virus had been hospitalized. In addition, severe illness and death had occurred in pregnant women, including a higher fatality rate compared to general population.

Symptomatic treatment: See discussion under CAP.

Risks to Fetus: Influenza infection increases risk of preterm labor and spontaneous abortion. Fetal distress associated with severe maternal illness can occur.

Patient Education: Web information for patients to be downloaded include:

• For seasonal flu vaccine: http://www.cdc.gov/flu/about/qa/fluvaccine.htm
• For general flu: http://www.marchofdimes.com/pnhec/188_10596.asp

Pregnant women appear to suffer higher influenza-associated morbidity and mortality compared with women who are not pregnant. This is thought related to physiologic changes.

Varicella

The two scenarios most likely to confront an emergency physician are (1) a patient with varicella exposure and no symptoms, and (2) a patient with active infection. Although the focus of this paper is acute pulmonary disease, dealing with prevention of pneumonia is deemed important.