Các Khuyến Cáo Tạm Thời Cập Nhật dành cho Nhà Cung Cấp Dịch Vụ Y Tế Sản Khoa liên quan đến Việc Sử Dụng Thuốc Kháng Vi-rút trong Điều Trị và Phòng Ngừa Cúm trong Mùa Cúm 2009-2010

Ngày 29 Tháng Mười Hai năm 2009, 1:30 Chiều - Giờ Miền Đông

These recommendations have been updated to provide additional guidance for obstetric health care providers in prescribing antiviral medications for treatment and prevention of influenza during the 2009-2010 season. This document, last updated on September 17, 2009, has been updated to:

• Include women up to 2 weeks postpartum (including following pregnancy loss) as at higher risk for complications from 2009 H1N1 influenza.
• Provide additional information on dosing and length of treatment for severely ill patients.  
• Add link to information on oseltamivir (Tamiflu®) or zanamivir (Relenza®) from US Food and Drug Administration (FDA).
• Provide further clarification of recommendations for chemoprophylaxis by providing definition of "close contact" with a person likely to be infectious with influenza. 

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• Pregnant women are at higher risk for severe complications and death from influenza, including both 2009 H1N1 influenza and seasonal influenza. Changes in the immune, respiratory and cardiovascular systems that occur during pregnancy result in pregnant women being more severely affected by certain pathogens, including influenza.

• Postpartum women, who are in transition to normal immune, cardiac, and respiratory function, should be considered to be at increased risk of influenza-related complications up to 2 weeks postpartum (including following pregnancy loss).

• Treatment with antiviral medications is recommended for pregnant women or women who are up to 2 weeks postpartum (including following pregnancy loss) with suspected or confirmed influenza and can be taken during any trimester of pregnancy. The duration of antiviral treatment is 5 days. See Table 1 (below) for dosing information.

• Hospitalized patients with severe infections (such as those with prolonged infection or who require intensive care unit admission) might require longer treatment courses. Some experts have advocated use of increased (doubled) doses of oseltamivir for some severely ill patients, although there are no published data demonstrating that higher doses are more effective.

• Oseltamivir and zanamivir are antiviral medications that are FDA approved for treatment of influenza.
  Pregnancy should not be considered a contraindication to oseltamivir or zanamivir use. These medications are "Pregnancy Category C" medications, indicating that no clinical studies have been conducted to assess the safety of these medications for pregnant women. However, the available risk-benefit data indicate pregnant women with suspected or confirmed influenza should receive prompt antiviral therapy.

• Treatment should be initiated as early as possible because studies show that treatment initiated early (i.e., within 48 hours of illness onset) is more likely to provide benefit. However, some studies of hospitalized patients with seasonal and 2009 H1N1 influenza have suggested benefit of antiviral treatment even when treatment was started more than 48 hours after illness onset.

• Treatment should not wait for laboratory confirmation of influenza because laboratory testing can delay treatment and because a negative rapid test for influenza does not rule out influenza. The sensitivity of rapid tests can range from 10 % to 70%. See CDC's information on the use of rapid influenza diagnostic tests.

• For treatment of pregnant women or women who are up to 2 weeks postpartum (including following pregnancy loss) with suspected or confirmed influenza, oseltamivir is currently preferred because of its systemic absorption.  See Table 1 (below) for dosing information.

• At this time, most 2009 H1N1 influenza viruses are susceptible to oseltamivir and zanamivir.  However, antiviral treatment regimens might change depending on new antiviral resistance or viral surveillance information.

• Based on global experience to date, 2009 H1N1 influenza viruses likely will be the most common influenza virus among those circulating in the coming season, particularly those causing influenza among younger age groups.

• Since rapid access to antiviral medications is essential, health care providers who care for pregnant and postpartum (including following pregnancy loss) women should develop methods to ensure that treatment can be started quickly after symptom onset. Actions that will support early treatment initiation include:

  • Informing pregnant and postpartum (including following pregnancy loss) women of signs and symptoms of influenza and the need for early treatment after onset of symptoms. In a recent case series of pregnant women with 2009 H1N1 influenza, manifestations included fever (97%), cough (94%) rhinorrhea (59%), sore throat (50%), headache (47%), shortness of breath (41%), myalgia (35%), vomiting (18%), diarrhea (12%) and conjunctivitis (9%), similar to those in the general population.  Individuals may be infected with influenza, including 2009 H1N1, and have respiratory symptoms without fever.

  • Ensuring rapid access to telephone consultation and clinical evaluation for pregnant and postpartum (including following pregnancy loss) women

  • Considering empiric treatment of pregnant women and women who are up to 2 weeks postpartum (including following pregnancy loss) based on telephone contact if hospitalization is not indicated and if this will substantially reduce delay before treatment is initiated

• Post-exposure antiviral chemoprophylaxis can be considered for pregnant women and women who are up to 2 weeks postpartum (including following pregnancy loss) who have had close contact with someone likely to have been infectious with influenza. Close contact, for the purposes of this document, is defined as having cared for or lived with a person who has confirmed, probable, or suspected influenza, or having been in a setting where there was a high likelihood of contact with respiratory droplets and/or body fluids of such a person. Examples of close contact include sharing eating or drinking utensils or physical examination. Close contact typically does not include activities such as walking by an infected person or sitting across from a symptomatic patient in a waiting room or office.

• The drug of choice for chemoprophylaxis of pregnant women and women who are up to 2 weeks postpartum (including following pregnancy loss) is less clear. Zanamivir may be the preferable antiviral for chemoprophylaxis of pregnant women because of its limited systemic absorption. However, respiratory complications 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. For these women, oseltamivir is a reasonable alternative.  The duration of antiviral chemoprophylaxis post-exposure is 10 days after the last known exposure. See Bảng 1 (below) for dosing information.

• Pregnant women and women who are up to 2 weeks postpartum (including following pregnancy loss) who are given post-exposure chemoprophylaxis should be informed that the chemoprophylaxis lowers but does not eliminate the risk of influenza and that protection stops when the medication course is stopped. Those receiving chemoprophylaxis should be encouraged to seek medical evaluation as soon as they develop a febrile respiratory illness that might indicate influenza.

• All pregnant women should be counseled about the early signs and symptoms of influenza infection and advised to immediately call for evaluation if clinical signs or symptoms develop while pregnant or in the first two weeks after delivery or pregnancy loss.  

• Early treatment is an alternative to chemoprophylaxis for some pregnant and postpartum (including following pregnancy loss) women who have had contact with someone likely to have been infectious with influenza.  Clinical judgment is an important factor in treatment decisions.

• Fever in pregnant women should be treated because of the risk that it appears to pose to the fetus.  Acetaminophen appears to be the best option for treatment of fever during pregnancy.