2009 H1N1 Flu: CDC Response

Updated: January 12, 2010

CDC continues to respond to the 2009 H1N1 influenza virus. CDC’s response goals since the emergence of the pandemic have been 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. CDC’s response to the pandemic has included:

Clinician Guidance

CDC issued interim guidance for clinicians on identifying and caring for patients with 2009 H1N1influenza. Special guidance also was 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 provided interim guidance on the use of antiviral drugs. Guidance was and continues to be continually reviewed and updated as the situation warrants.

Public Guidance

CDC 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 issued instruction son taking care of a sick person at home and the use of facemasks and respirators to reduce 2009 H1N1 transmission. CDC also provided advice on everyday preventive actions that people could take to stop the spread of germs, including staying home when sick in order to limit further spread of the disease. CDC 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 guidance was designed to decrease the spread of regular seasonal flu and 2009 H1N1 flu while limiting the disruption of day-to-day activities and the vital learning that goes on in schools. In addition, CDC 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 kits 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 also sent test kits internationally to more than 130 countries. In addition, the world widespread of 2009 H1N1 virus highlighted the need to evaluate commercially available, widely used, rapid influenza diagnostic tests (RIDT's) for their ability to detect viral antigens in respiratory clinical specimens. As an initial assessment, CDC conducted an evaluation of multiple RIDTs. Findings indicated 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. CDC advised that patients with illnesses compatible with 2009 H1N1 virus infection but with negative RIDT should be treated based on the level of clinical suspicion, underlying medical conditions, severity of illness, and risk for complications.

Vaccines

CDC isolated the new H1N1 virus and prepared and provided vaccine viruses to manufacturers to use in the production of a vaccine against 2009 H1N1. These vaccines were produced by the same manufacturers that make seasonal flu vaccines in the same way that seasonal flu vaccines are made. The same safety systems were used for these vaccines as well, which included the successful completion of clinical trials. The first doses of vaccines against 2009 H1N1 were available for shipping in October. By the end of 2009,more than 100 million doses of 2009 H1N1 vaccine had been made available. As supplies of vaccine increased, many places opened up vaccination to everyone.

Stockpile Deployment

In April 2009, 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.

In October, U.S. Department of Health and Human Services (HHS) approved the release of 300,000 bottles of Tamiflu® oral suspension to fill production gap and meet the increasing demand of this formulation. As the situation progressed, CDC SNS distributed 234,000 additional bottles of suspension to all U.S. states and territories to continue the federal government’s commitment to the nation’s response to the H1N1 influenza outbreak.
Also in October, HHS authorized the release of 59.5 million N95 respirators to all U.S. states and territories that requested them.

On October 23rd, 2009, FDA issued an Emergency Use Authorization (EUA) for Peramivir IV. Peramivir IV is an investigational intravenous antiviral drug used to treat people who have been hospitalized due to severe flu illness. This drug is being held in the Strategic National Stockpile (SNS) and distributed by CDC under an EUA.

Licensed clinicians may make requests for this product through the CDC website electronic request system. For additional information regarding peramivir and SNS distribution of this product please see "Emergency Use Authorization (EUA) of Medical Products and Devices" .

Surveillance

Currently,flu activity, including 2009 H1N1 activity, is being detected through CDC’s influenza surveillance systems and reported weekly in FluView. CDC worked with the Council of State and Territorial Epidemiologists (CSTE) to enhance surveillance for 2009 H1N1 flu during the 2009-10 flu season, including implementing a new web-based Aggregate Hospitalization and Death Reporting Activity (AHDRA). The Emerging Infections Program(EIP), begun in 2004 to conduct surveillance for laboratory-confirmed influenza hospitalizations, was expanded in the fall by an additional 6 sites representing 40 counties. EIP now represents 8.5% of the U.S. population. In addition, CDC developed a method to provide an estimated range of the total number of 2009 H1N1 cases, hospitalizations and deaths in the United States since April, 2009, as well as a breakdown of these estimates by age groups. CDC made the first set of estimates available on November12 and committed to updating these figures every three to four weeks.