Novel H1N1 Flu: CDC Response

Updated: August 19, 2009

CDC is taking aggressive action to respond to the new 2009 H1N1 influenza virus and a possibly severe upcoming flu season. CDC’s response goals are to reduce the spread and severity of illness, and to provide information to help health care providers, public health officials and the public address the challenges posed by this public health threat. While the timing, spread and severity of the upcoming U.S. flu season are uncertain, CDC anticipates that 2009 H1N1 influenza viruses and regular seasonal influenza may spread at the same time. It’s possible that a lot more people will get sick this season than normally occurs during a regular flu season. There also may be more people hospitalized and more deaths this season than during a normal flu season.

Clinician Guidance

CDC has issued interim guidance for clinicians on identifying and caring for patientswith 2009 H1N1 influenza. Special guidance also has been prepared for clinicians caring for patients who are at high risk of serious complications from infection with the new H1N1 virus, including pregnant women, infants and young children, people with HIV/AIDS, and people with heart disease. In addition CDC has provided interim guidance on the use of antiviral drugs. Influenza antiviral drugs are prescription medicines (pills, liquid or an inhaled powder) with activity against influenza viruses, including 2009 H1N1 influenza. The priority use for influenza antiviral drugs during the 2009 H1N1 outbreak is to treat people hospitalized with influenza illness, and to treat people who are sick and who are at increased risk of severe illness, including pregnant women, young children, and people with chronic health conditions like asthma, diabetes and other metabolic diseases, heart or lung disease, kidney disease, weakened immune systems, and persons with neurologic or neuromuscular disease. Guidance is being continually reviewed and will be updated as the evolving situation warrants.

Public Guidance

CDC has provided guidance for the public on what to do if they become sick with flu-like symptoms, including infection with 2009 H1N1 influenza. CDC also has issued instructions on taking care of a sick person at home and the use of facemasks and respirators to reduce 2009 H1N1 transmission. Everyone should take everyday preventive actions to stop the spread of germs, including frequent hand washing and people who are sick should stay home and avoid contact with others in order to limit further spread of the disease. CDC has also released guidance and a tool kit for school administrators and health officials to help decrease the spread of flu among students and school staff during the 2009-2010 school year. The new guidance is designed to decrease the spread of regular seasonal flu and the 2009 H1N1 flu while limiting the disruption of day-to-day activities and the vital learning that goes on in schools. In addition, CDC has prepared downloadable flyers and brochures, including a guide for parents and a brochure for people with chronic underlying health conditions that place them at higher risk of serious flu-related complications (like asthma and diabetes, for example).

Testing

At the beginning of the 2009 H1N1 outbreak, CDC developed a diagnostic kit to test for this new virus and began distributing the test kit on May 1, 2009. By May 7, CDC had sent the test kit to all 50 states, Puerto Rico and the District of Columbia. CDC has also sent test kits internationally to more than 130 countries. In addition, the worldwide spread of 2009 H1N1 virus highlighted the need to evaluate commercially available, widely used, rapid influenza diagnostic tests (RIDTs) for their ability to detect viral antigens in respiratory clinical specimens.  As an initial assessment, CDC conducted an evaluation of multiple RIDTs.  Findings indicate that, although a positive RIDT result can be used in making treatment decisions, a negative result does not rule out infection with 2009 H1N1 virus. Patients with illnesses compatible with 2009 H1N1 virus infection but with negative RIDT results should be treated based on the level of clinical suspicion, underlying medical conditions, severity of illness, and risk for complications.

Vaccine

A vaccine to protect against the 2009 H1N1 virus is expected to be available this fall and manufacturing is underway.  CDC's Advisory Committee on Immunization Practices has made recommendations for the use of 2009 H1N1 vaccination. Various clinical trials on the 2009 H1N1 vaccine have begun, some under the direction of the National Institutes of Health and others by manufacturers under contract with Health and Human Services. Additional information can be found at http://www.cdc.gov/h1n1flu/vaccination/, including steps to take until the vaccine is available.

Stockpile Deployment

CDC deployed 25 percent of the pandemic influenza supplies in the Strategic National Stockpile (SNS) to all U.S. states and territories.  These included antiviral drugs, personal protective equipment and respiratory protection devices.  CDC is currently replenishing the antiviral drugs deployed in April in order to be ready for the upcoming fall flu season.

Surveillance

Currently, 2009 H1N1 activity is being detected through CDC’s influenza surveillance systems and reported weekly in FluView. CDC continues to work with the Council of State and Territorial Epidemiologists (CSTE) to determine ways to enhance surveillance for 2009 H1N1 flu during the 2009-10 flu season.  In addition, a subset of states will participate in an influenza incidence study, which is intended to help scientists better understand disease trends over time in a community.