No definitive data, but masks may block flu

Offer coughing patients masks

Beset by influenza questions in a season without sufficient vaccine, the Centers for Disease Control and Prevention recently issued some guidance on the role of masks to prevent flu transmission.

Human influenza is transmitted from person to person primarily via virus-laden large droplets (particles > 5 µm in diameter) that are generated when infected people cough or sneeze; these large droplets then can be deposited directly onto the mucosal surfaces of the upper respiratory tract of susceptible people who are near (i.e., within 3 feet) the droplet source. Transmission also may occur through direct and indirect contact with infectious respiratory secretions.

A combination of infection control strategies is recommended to decrease transmission of influenza in health care settings. These include placing influenza patients in private rooms when possible and having health care personnel wear masks for close patient contact (i.e., within 3 feet) and gowns and gloves if contact with respiratory secretions is likely. The use of surgical or procedure masks by infectious patients may help contain their respiratory secretions and limit exposure to others.

Likewise, when a patient is not wearing a mask, as when in an isolation room, having health care personnel mask for close contact with the patient may prevent nose and mouth contact with respiratory droplets.

However, no studies have definitively shown that mask use by either infectious patients or health care personnel prevents influenza transmission.

During periods of increased respiratory infection activity in the community, masks should be offered as part of a respiratory hygiene/cough etiquette strategy to patients who are coughing or have other symptoms of a respiratory infection when they present for health care services.

Patients: Masks should be worn by these patients until one of these situations occur:

1. It is determined that the cause of symptoms is not an infectious agent that requires isolation precautions to prevent respiratory droplet transmission.
2. The patient has been isolated appropriately, either by placement in a private room or by placement in a room with other patients with the same infection (cohorting). Once isolated, the patient does not need to wear a mask unless transport outside the room is necessary.

Health care personnel: A surgical or procedure mask should be worn by health care personnel who are in close contact (i.e., within 3 feet) with a patient who has symptoms of a respiratory infection, particularly if fever is present, as recommended for standard and droplet precautions. These precautions should be maintained until the patient has been determined to be noninfectious or for the duration recommended for the specific infectious agent.