Swine Flu Update: WHO Declares Pandemic In Response To Ongoing Global Spread Of Novel Influenza A (H1N1) Virus

More than 70 countries are now reporting cases of human infection with novel H1N1 flu. This number has been increasing over the past few weeks, but many of the cases reportedly had links to travel or were localized outbreaks without community spread. The WHO designation of a pandemic alert Phase 6 reflects the fact that there are now ongoing community level outbreaks in multiple parts of world.

WHO’s decision to raise the pandemic alert level to Phase 6 is a reflection of the spread of the virus, not the severity of illness caused by the virus. It’s uncertain at this time how serious or severe this novel H1N1 pandemic will be in terms of how many people infected will develop serious complications or die from novel H1N1 infection. Experience with this virus so far is limited and influenza is unpredictable. However, because novel H1N1 is a new virus, many people may have little or no immunity against it, and illness may be more severe and widespread as a result. In addition, currently there is no vaccine to protect against novel H1N1 virus.

In the United States, most people who have become ill with the newly declared pandemic virus have recovered without requiring medical treatment, however, CDC anticipates that there will be more cases, more hospitalizations and more deaths associated with this pandemic in the coming days and weeks. In addition, this virus could cause significant illness with associated hospitalizations and deaths in the fall and winter during the U.S. influenza season.

Background

Novel influenza A (H1N1) is a new flu virus of swine origin that first caused illness in Mexico and the United States in March and April, 2009. It’s thought that novel influenza A (H1N1) flu spreads in the same way that regular seasonal influenza viruses spread, mainly through the coughs and sneezes of people who are sick with the virus, but it may also be spread by touching infected objects and then touching your nose or mouth. Novel H1N1 infection has been reported to cause a wide range of flu-like symptoms, including fever, cough, sore throat, body aches, headache, chills and fatigue. In addition, many people also have reported nausea, vomiting and/or diarrhea.

The first novel H1N1 patient in the United States was confirmed by laboratory testing at CDC on April 15, 2009. The second patient was confirmed on April 17, 2009. It was quickly determined that the virus was spreading from person-to-person. On April 22, CDC activated its Emergency Operations Center to better coordinate the public health response. On April 26, 2009, the United States Government declared a public health emergency and has been actively and aggressively implementing the nation’s pandemic response plan.

Since the outbreak was first detected, an increasing number of U.S. states have reported cases of novel H1N1 influenza with associated hospitalizations and deaths. By June 3, 2009, all 50 states in the United States and the District of Columbia and Puerto Rico were reporting cases of novel H1N1 infection. While nationwide U.S. influenza surveillance systems indicate that overall influenza activity is decreasing in the country at this time, novel H1N1 outbreaks are ongoing in parts of the U.S., in some cases with intense activity.

CDC is continuing to watch the situation carefully, to support the public health response and to gather information about this virus and its characteristics. The Southern Hemisphere is just beginning its influenza season and the experience there may provide valuable clues about what may occur in the Northern Hemisphere this fall and winter.

CDC Response

CDC continues to take aggressive action to respond to the outbreak. 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 new public health threat.

CDC is issuing updated interim guidance in response to the rapidly evolving situation (see: http://www.cdc.gov/h1n1flu/recommendations.htm).

Clinician Guidance

CDC has issued interim guidance for clinicians on identifying and caring for patients with novel H1N1 (see: http://www.cdc.gov/h1n1flu/identifyingpatients.htm), in addition to providing interim guidance on the use of antiviral drugs (see: http://www.cdc.gov/h1n1flu/recommendations.htm). Influenza antiviral drugs are prescription medicines (pills, liquid or an inhaled powder) with activity against influenza viruses, including novel influenza H1N1 viruses. The priority use for influenza antiviral drugs during this outbreak is to treat people hospitalized with influenza illness, and to treat people 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.

Public Guidance

CDC has provided guidance for the public on what to do if they become sick with flu-like symptoms, including infection with novel H1N1 (see: http://www.cdc.gov/h1n1flu/sick.htm). CDC also has issued instructions on taking care of a sick person at home (see: http://www.cdc.gov/h1n1flu/guidance_homecare.htm) and the use of facemasks and respirators to reduce novel influenza A (H1n1) transmission (see: http://www.cdc.gov/h1n1flu/masks.htm). 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.

Testing

CDC has developed a PCR diagnostic test kit to detect this novel H1N1 virus and has now distributed test kits to all states in the U.S. and the District of Columbia and Puerto Rico. The test kits are being shipped internationally as well. This will allow states and other countries to test for this new virus.

Vaccine

Vaccines are a very important part of a response to pandemic influenza and the U.S. Government is aggressively taking early steps in the process to manufacture a novel H1N1 vaccine, working closely with manufacturers. CDC has isolated the new H1N1 virus, made a candidate vaccine virus that can be used to create vaccine, and has provided this virus to industry so they can begin scaling up for production of a vaccine, if necessary. Making vaccine is a long multi-step process requiring several months to complete.

Stockpile Deployment

CDC has deployed 25 percent of the supplies in the Strategic National Stockpile (SNS) to all states in the continental United States and U.S. territories. This included antiviral drugs, personal protective equipment, and respiratory protection devices. The influenza A (H1N1) virus is susceptible to the prescription antiviral drugs oseltamivir and zanamivir. These supplies and medicines will help states and U.S. territories respond to novel H1N1 virus.

Surveillance

Novel influenza A (H1N1) activity is now being detected through CDC’s routine influenza surveillance systems and reported weekly in FluView. CDC tracks U.S. influenza activity through multiple systems across five categories. While our influenza surveillance systems indicate that overall influenza activity is decreasing in the United States, novel H1N1 outbreaks are ongoing in different parts of the U.S., in some cases with intense influenza-like activity. Most of the influenza viruses being detected now are novel H1N1 viruses.

Shared Responsibility

Individuals have an important role in protecting themselves and their families.

• Stay informed. Health officials will provide additional information as it becomes available.
• Everyone should take these everyday steps to protect your health and lessen the spread of this new virus:
  • Cover your nose and mouth with a tissue when you cough or sneeze. Throw the tissue in the trash after you use it.
  • Wash your hands often with soap and water, especially after you cough or sneeze. Alcohol-based hand cleaners are also effective.
  • Avoid touching your eyes, nose or mouth. Germs spread this way.
  • Try to avoid close contact with sick people.
  • If you are sick with a flu-like illness, stay home for 7 days after your symptoms begin or until you have been symptom-free for 24 hours, whichever is longer. This is to keep from infecting others and spreading the virus further.
  • Follow public health advice regarding school closures, avoiding crowds and other social distancing measures.