Pandemic influenza medical countermeasures Jo Hofmann MD Communicable

Pandemic influenza: medical counter-measures Jo Hofmann, MD Communicable Disease Epidemiology Section Washington State Department of Health July 2006

Influenza - overview • Review the difference between seasonal, avian and pandemic influenza • Update on avian influenza (H 5 N 1) situation in Asia, Europe, Middle East and Africa • Discuss the use of medical interventions to control the spread of pandemic influenza

Seasonal, avian or pandemic? • Seasonal influenza § Flu that circulates each winter; the virus changes a little from year-to-year • Avian influenza § A common infection of birds but virus may also infect other species • Pandemic influenza § A widespread, multi-continental outbreak of serious human influenza § Caused by a new virus adapted to spread quickly between people

How is influenza spread? • Flu virus infects cells in nose and throat • Virus can be spread 24 hours before a person is ill until 5 -7 days later • Spread by coughing, sneezing and surfaces contaminated with flu virus

Influenza virus subtypes Neuraminidase “N” • Proteins determine characteristics of a virus § Which species it infects § How deadly it is to host • 2 proteins on surface determine virus subtype § Hemagglutinin (“H”) § Neuraminidase (“N”) Hemagglutinin “H” • Virus subtypes designated by H and N numbers v For example -- H 5 N 1, H 3 N 2

Influenza virus • Infects people, animals and/or birds • Has a simple genetic structure • Likes to share genes and evolves by: RNA genes § Mutation § Reassortment

Areas with confirmed H 5 N 1 influenza in poultry and/or wild birds, 2003 -06 As of August 2, 2006

Areas with confirmed H 5 N 1 influenza in people, 2003 -06 As of August 9, 2006 Total cases 241 Total deaths 141

Avian influenza and pandemics • All 20 th century pandemics were caused by a virus closely related to avian influenza • Genetic fingerprint of the 1918 -1919 “Spanish” influenza pandemic virus looks “avian-like” but the actual source of the virus is unknown

Controlling the spread of influenza

Medical counter-measures • List is small § Influenza vaccine § Antiviral medications

Annual process of development, manufacturing, and distribution of influenza vaccine: January- May

Annual process of developing, manufacturing and distribution of influenza vaccine: May-October Source: Treanor, J. N Engl J Med 2004; 351: 2037 -2040

Problems with vaccine in a pandemic • Current technology can’t produce vaccine without knowing virus structure § Is H 5 N 1 a future pandemic virus? • Vaccine unlikely to be available until months into pandemic • Federal gov’t will probably control distribution of limited vaccine supplies to state and local government agencies

Influenza antivirals • Medications to treat or prevent influenza § M 2 inhibitors - amantidine, rimantidine v. First approved in 1976 v. No longer recommended due to resistant influenza strains § Neuraminidase inhibitors – oseltamivir, zanamivir (Tamiflu®, Relenza®) v. First approved in 1999

Antivirals – how they work M 2 inhibitors (amantidine, rimantidine) Neuraminidase inhibitors (oseltamivir, zanamivir)

Neuraminidase inhibitors • Compared with M 2 inhibitors, fewer side effects but more $$$$$$ • Can reduce duration of flu symptoms by 24 hours if taken within the first 48 hours of illness • Can reduce chance of getting flu if exposed • None shown to reduce the complications associated with flu • Seasonal influenza viruses and H 5 N 1 have been identified that are resistant to oseltamivir

Problems with antivirals in a pandemic • Pandemic virus could be resistant • Antivirals may not prevent flu complications or deaths • HHS stockpile enough to treat only 25% of the US population • Waiting list for state/local stockpiles orders is long • Current guidelines are for treatment, not prevention of influenza

Summary • No magic bullets for the pandemic • We need more research and improved technology for vaccine and antiviral production • We need more information on how well other prevention measures work • A combination of measures will be needed to limit a pandemic

The estimated impact of a pandemic on the US and Washington State Moderate (1957/68 -like) Severe (1918 -like) US Washington Outpatient care 23– 54 million . 5 – 1. 1 million 45 million 943, 000 Hospital Care . 5– 1. 2 million 10 -24, 000 9. 9 million 210, 009 ICU care 77– 180, 000 15– 3600 1. 5 million 31, 500 Deaths 117– 270, 000 23– 5400 1. 9 million 40, 400

Modern Quarantine Honey - will you join me in registering our whereabouts with the appropriate government bureaucracies? Oh, Jim you romantic fool – of course I’ll wear my CDC Division of Global Migration and Quarantine Electronic Locator Ring™