Novel H1N1 Influenza Continues to Spread in United States

More than 1 million persons in the United States may have been infected with novel H1N1 (swine) influenza virus, according to US health officials. In a recent media briefing, Dr Anne Schuchat, Director of the National Center for Immunization and Respiratory Diseases, CDC, noted that the infection is continuing to spread well past the typical influenza season in the Northern Hemisphere. The 6000 new cases reported last week represent the largest 1-week increase since the start of the outbreak in April.

The H1N1 vaccine currently in development will be tested in clinical trials this summer. Although the CDC has not yet established recommendations for vaccination, the focus will most likely be on children and adolescents, pregnant women, and persons with underlying chronic disorders, such as asthma and diabetes, that put them at risk for influenza-related complications.

In the meantime, health care providers are urged to follow infection-control procedures to protect themselves from novel H1N1 influenza. Of 26 confirmed cases among health care workers, 50% became infected while at work, according to a report in the June 19 issue of the CDC’s Morbidity and Mortality Weekly Report. The risk of transmission is greatest in the outpatient setting.

The CDC’s interim infection-control recommendations for the care of patients with novel H1N1 influenza include the use of fit-tested N95 respirators, eye protection, and contact precautions in addition to routine infection-control practices applied to seasonal influenza. The CDC also recommends that aerosol-generating procedures (eg, bronchoscopy) be performed in an airborne infection-isolation room with negative pressure air handling.