The CDC provides regular updates on the Novel H1N1 flu and public resources at http://www.cdc.gov/h1n1flu.
Information for businesses can be found at: http://www.cdc.gov/h1n1flu/business.
Information for day care, schools and colleges can be found at http://www.cdc.gov/h1n1flu/schools.
Information for families and caregivers can be found at http://www.cdc.gov/h1n1flu/parents.





The Flu
The flu is a respiratory illness caused by infection with the influenza virus. Three types of influenza virus can cause disease in humans: influenza A, influenza B and influenza C. Influenza A and B viruses are associated with yearly seasonal outbreaks of flu. Influenza C tends to cause mild infections and is generally thought not to cause serious outbreaks.

Influenza A viruses can be further classified by two proteins found on the surface of the virus cells: hemagglutinin (referred to as H) and neuraminidase (N). Scientists have identified 16 different subtypes of hemagglutinin, among which H1, H2 and H3 are most associated with human disease. There are 9 subtypes of neuraminidase.

Seasonal flu appears in the U.S. during the fall and winter, with most illnesses occurring from November through March. The virus is spread through contact with contaminated respiratory droplets. Incubation is from one to four days. Signs include: sudden fever, dry cough, headache, sore throat, tiredness, sneezing, runny or stuffy nose, chills, fatigue and muscle aches.

Most patients recover in a few days to two weeks, though weakness and fatigue may persist. Some people develop serious complications from the flu, like pneumonia, bronchitis or exacerbation of underlying medical conditions. People 65 and older, young children, pregnant women, and those with weakened immune systems or chronic medical conditions are most at risk for developing flu complications.

During an average flu season, 5 to 20 percent of Americans will get the flu. More than 200,000 people require hospitalization and 36,000 die from flu complications.

Flu Pandemics
A pandemic is a worldwide outbreak of a disease. An influenza pandemic typically occurs when a new flu virus appears, for which humans have little or no immunity. The virus may have mutated into a new strain, or an animal virus may jump species and begin to infect humans. With no prior exposure, large numbers of people become sick.

The World Health Organization (WHO) monitors influenza outbreaks and posts alerts based on the potential threat level to humans:

* Phase 1 - no animal viruses have been detected in humans
* Phase 2 - a flu virus normally circulating only in animals has been reported to cause illness in humans.
* Phase 3 – the virus has caused sporadic clusters or small clusters of illness. At this point, human-to-human transmission of the new virus is very rare.
* Phase 4 – human-to-human transmission has been verified, increasing the risk of community or sustained outbreaks.
* Phase 5 – human-to-human spread of the virus has been confirmed in at least two countries in one designated WHO region.
* Phase 6 (the pandemic phase) – community level outbreaks have been reported in at least one other country in a different WHO region.



During a pandemic, a large number of people can become sick at the same time and death rates can be high. Here is a brief overview of the three major pandemics that hit in the last 100 years:

1918 - It was caused by the H1N1 virus and referred to as the Spanish flu. Up to 40 percent of the world’s population got sick and more than 50 million died. In the U.S. alone, there were about 675,000 deaths from the flu. Some died within hours of becoming ill.

1957 – This pandemic was caused by the H2N2 flu virus and referred to as the Asian flu. This pandemic hit the U.S. in two waves. In the first, school children spread the virus to classmates and families. Infection rates were highest among children, young adults and pregnant women, but rate of death was highest among the elderly. Viral activity appeared to settle by the end of 1957. However, between January and February, there was a resurgence of cases among the elderly. In total, about 69,800 people in the U.S. died from the Asian flu.

1968 – The 1968 pandemic was caused by the H3N2 flu virus and called the Hong Kong flu. While the virus reached the level of a pandemic, the rate of death was relatively low. Between September 1968 and March 1969, about 33,800 people in the U.S. died from the flu. Rates of death were higher among those over 65.



The Novel H1N1 Flu
The current flu concern, formerly called the swine flu, is now referred to as novel H1N1 flu. The first cases were reported in April 2009 in Mexico. Soon after, two confirmed cases in children were identified in California, near the Mexican border. The virus was eventually typed and found to be a strain of type A influenza of the H1N1 serotype. Although the virus originated in pigs (hence the earlier reference to “swine” flu), researchers found it was actually a new virus with genetic components of influenza viruses from swine, birds and humans.

The H1N1 virus has spread rapidly. By early June nearly 30,000 cases were reported in 74 countries. On June 11th, the World Health Organization raised the pandemic alert level to phase 6, marking the start of the 2009 influenza pandemic. By June 19th, H1N1 cases of infection were reported in all 50 states, the District of Columbia, Puerto Rico and the U.S. Virgin Islands. As of August 28, the CDC reports more than 8,800 people in the U.S. have been hospitalized for H1N1 flu complications. More than 550 people have died from the illness. The U.S. continues to report the largest number of cases of H1N1 infection in the world.

So far, death rates from the flu have been relatively low. However, health experts fear that could change if the flu virus mutates into a more potent strain. Like the H1N1 virus that caused the 1918 pandemic, risk for infection, complications and death appears to be highest among younger people.

Scientists expect that, as children return to school, the number of cases of H1N1 infection will rapidly increase. John Treanor, M.D., Infectious Diseases Expert with the University of Rochester Medical Center, says when a new flu strain emerges, infection may hit 40 percent or more of the population, many of them becoming ill around the same time. If that happens, schools, businesses and basic services (like public transportation) may be temporarily shut down because there may not be enough healthy people to keep services running. Some economists fear a widespread flu outbreak could disrupt delivery of food and consumer goods, eventually having an impact on local economies.

Combatting the Flu
As public health officials gear up for this year’s flu season, there are two main concerns – the Novel H1N1 flu AND the regular seasonal flu. The regular flu shot to protect against seasonal flu will not provide immunity to H1N1. Currently, several manufacturers are testing vaccines to protect against the Novel H1N1 flu.

In the meantime, production of the seasonal flu vaccine has been ramped up. About half the doses are expected to be available by the end of August and the rest by the end of September. Health experts are recommending seasonal flu vaccination as soon as possible for high risk groups, including the elderly, children 6 months to 18 years, health care workers, patients with chronic diseases or weak immune system, adults 50 and older and household contacts of those at high risk of flu complications.

The first batches of the H1N1 vaccine are expected to be available sometime in September/early October (although production delays may set these dates back further). The first doses will be targeted for children, young adults, pregnant women, health care workers, patients 25 to 64 with chronic medical conditions and caregivers of children under six months. Researchers say two doses of the H1N1 vaccine may be needed to provide optimal protection.

Immunologist, David Topham, Ph.D., says older people seem to have some immunity against the H1N1 virus. However, young adults are expected to be hit hard. No one knows why young, seemingly healthy people are so susceptible. Some people believe the virus causes the immune system to overreact, increasing the risk for more severe illness and complications.

For patients who become ill, antiviral medications can be used. Currently, four antiviral medications are approved in the U.S. – oseltamivir (TAMIFLU®), zanamivir (RELENZA®), amantadine (SYMMETREL®) and rimantadine (Flumadine®). Scientists have found that H1N1 is resistant to amantadine and rimantadine, but so far, is still susceptible to oseltamivir and zanamivir.

As with seasonal flu, there are steps to take to reduce risk for H1N1 infection. Everyone should practice good hygiene - wash your hands frequently and avoid touching your eyes, nose or mouth (you can pick up flu germs by touching contaminated surfaces). Those who are sick should avoid contact with healthy people and stay home until 24 hours after the fever is gone. For most healthy people, that’s 3 to 5 days after the first symptoms.

Public health officials also recommend that employers and school administrators take steps to reduce potential spread of the virus and develop contingency plans if many key personnel are unable to come to work. Families need to be prepared with a stockpile of food, water and illness remedies in case caregivers are unable to leave the house. Parents also need to have back-up arrangements for child care if a child becomes sick or if day cares or schools need to close because of high infection rates or lack of support staff.

AUDIENCE INQUIRY
For information on seasonal flu or H1N1 flu:
Centers for Disease Control and Prevention, http://www.cdc.gov, or http://www.pandemicflu.gov

Information for businesses can be found at: http://www.cdc.gov/h1n1flu/business.

Information for day care, schools and colleges can be found at http://www.cdc.gov/h1n1flu/schools.

Information for families and caregivers can be found at http://www.cdc.gov/h1n1flu/parents.

BIBLIOGRAPHY
Chang, Luan-Yin, et al., “Novel Swine-origin Influenza Virus A (H1N1),” Journal of the Formosan Medical Association, July 2009, Vol. 108, No. 7, pp. 526-532.

Gallaher, William, “Towards a Sane and Rational Approach to Management of Influenza H1N1 2009,” Virology Journal, May 7, 2009, Vol. 6 No. 51.

Khanna, M., et al.,” Emerging Influenza Virus,” Journal of Bioscience, November 2008, Vol. 33, No. 4, pp. 475-482.

Khazeni, Nayer, M.D., et al., “Safety and Efficacy of Extended-Duration Antiviral Chemoprophylaxis Against Pandemic and Seasonal Influenza,” Annals of Internal Medicine, October 6, 2009, Vol. 151, No. 7 (early release).

Mossad, Sherif, M.D., The Resurgence of Swine-Origin Influenza A (h1N1),” Cleveland Clinic Journal of Medicine, June 2009, Vol. 76, No. 6, pp. 337-343.

Nelson, Martha, et al., “Multiple Reassortment Events in the Evolutionary History of H1N1 Influenza A Virus Since 1918,” PLoS Pathogens, February 29, 2008, Vol. 4, No. 2, p. 1000012.

Opstelten, Wim, et al., “Threat of an Influenza Pandemic,” BMC Family Practice, February 3, 2009, Vol. 10, No. 11.

“Prevention and Control of Seasonal Influenza with Vaccines,” MMWR: Morbidity and Mortality Weekly Report, July 31, 2009, Vol. 58, No. RR-8.

“Swine Influenza: Frequently Asked Questions,” Weekly Epidemiological Record, May 1, 2009, Vol. 84, No. 18, pp. 149-151.