Influenza A H1N1: A Pandemic in Real Time – What’s Next? Danny Chen, MD FRCPC MSc Infectious Disease Specialist Grand Rounds, York Central Hospital September 9, 2009

SEX

PB2 PB1 PA HA NP NA MP NS PB2 PB1 PA HA NP NA MP NS PB2 PB1 PA HA NP NA MP NS Classical swine, N. American lineage Avian, N. American lineage Human seasonal H3N2 Eurasian swine lineage Eurasian swine H1N1 N. American H1N1 (swine/avian/human) Pandemic (H1N1) 2009, combining swine, avian and human viral components Genetic origins of the pandemic (H1N1) 2009 virus: Quadruple viral reassortment

WHO phases of pandemic alert

Symptoms Definition of Influenza-like Illness (ILI): –Acute onset fever and cough AND –one or more of: Sore throat, arthralgia, myalgia, or prostration, –In children < 5 years of age, GI symptoms may also be present. –In patients 65 years fever may not be prominent. Guidance for Management of Patients with Influenza-like Illness (ILI) in Emergency Departments, MOHLTC June 4, 2009

Transmission

Prevention ENHANCED DROPLET PRECAUTIONS –Hand hygiene always –Gown, gloves, eye protection, N95 mask = droplet + contact + N95

Treatment Recommendations Oseltamivir recommended within 48 hours of the onset of symptoms: –ILI requiring hospitalization OR –ILI and at risk for complicated disease Other patients with ILI do not require treatment.

Laboratory confirmed cases of pandemic (H1N1) 2009 in Ontario by week between April 13 and August 29, 2009

Hospitalizations among confirmed cases of pandemic (H1N1) 2009 in Ontario, April 13 – September 3, 2009

Incidence of hospitalization and death due to pH1N1 in Ontario, April 13 to September 3, 2009

Seasonal influenza Every year:Every year: 5 million Canadians (1 in 6) will be infected5 million Canadians (1 in 6) will be infected –Up to 75,000 hospitalized – people will die 90% are >65 yrs90% are >65 yrs –half of those in LTCHs Bacterial pneumoniaBacterial pneumonia Cardiac failureCardiac failure Mortality rate: 13/100,000 population 0.2% of cases

PANDEMIC H1N CASES AT YCH Number Seen in ER and discharged 24 Hospitalized15 TOTAL39

So What Next

“Potential for catastrophe…” vs “…a pandemic dud.”

Laboratory confirmed cases of pandemic (H1N1) 2009 in Australia, to 28 August 2009 by jurisdiction

Rate of ILI reported from GP ILI surveillance systems from 2007 to 23 August 2009 by week

Rates of absenteeism of greater than 3 days absent, National employer, 1 January 2007 to 19 August 2009, by week

Hospitalised confirmed cases of pandemic (H1N1) 2009, by length of hospital stay and age group, to 28 August 2009, Australia

Age specific rates of hospitalised confirmed cases of pandemic (H1N1) 2009 compared with average annual age specific rates of hospitalisations from seasonal influenza, Australia

Hospitalized (n= 1145) Comorbidity64% (731) chronic respiratory51% (n=379) diabetes14% (n=107) pregnancy11% (n=77) chronic cardiac11% (n=84) immunocompromised11% (n=77) morbid obesity8% (n=57) renal5% (n=35)

Hospitalised confirmed cases of pandemic (H1N1) 2009 in pregnant women by weeks of gestation, to 28 August 2009, Australia

Numbers of deaths among confirmed cases of pandemic (H1N1) 2009, by age group and sex, compared with total laboratory confirmed pandemic (H1N1) 2009 notifications by age group Median age = 54 (cf seasonal flu: 83yo)

Percentage of all deaths classified as influenza and pneumonia, WA Registry of Births, Deaths and Marriages, 1 January 2008 to 23 August 2009

Seasonal Flu Pandemic H1N SymptomsSimilar TransmissionSame PreventionSame (enhanced droplet) SeveritySimilar Age affectedOlder (>65)Younger

But no room for complacency Pandemics take some time to get going (1918 and 1968). Some pandemic viruses have ‘turned nasty’ (1918 and 1968). There will be severely ill people and deaths — in risk groups (young children, pregnant women and especially people with underlying illnesses). Health services capacity? Resistance to antivirals? Attack rate? An inappropriate and excessive response to the pandemic could be worse than the pandemic itself…

“…the H1N1 influenza and influenza generally is unpredictable...” Dr. Anne Schuchat, CDC

Pandemic Model York Region Impact 35% of the population, including YCH staff, will be infected during the first wave of pandemic influenza Need to MAXIMIZE CAPACITY to manage increased patient volumes in the face of depleted resources

Summary H1N1 now the dominant virus strain Large populations susceptible to infection –Vaccine? Not the same as seasonal influenza –Age distribution Influenza is unpredictable Be prepared –Capacity, resources

Summary What next… –Replay the Australian experience?

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