Influenza A H1N1: A Pandemic in Real Time – What’s Next?

Danny Chen, MD FRCPC MScInfectious Disease Specialist

Grand Rounds, York Central HospitalSeptember 9, 2009

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Classical swine, N. American lineageAvian, N. American lineageHuman seasonal H3N2Eurasian 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 < 5 years of age or >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 hospitalizedUp to 75,000 hospitalized– 2000-4000 people will die 2000-4000 people will die

• 90% are >65 yrs90% are >65 yrs– half of those in LTCHshalf of those in LTCHs

• Bacterial pneumoniaBacterial pneumonia• Cardiac failureCardiac failure

Mortality rate:13/100,000 population0.2% of cases

PANDEMIC H1N1 2009

CASES AT YCHNumber

Seen in ER and discharged

24

Hospitalized 15

TOTAL 39

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)

Comorbidity 64% (731)

chronic respiratory 51% (n=379)

diabetes 14% (n=107)

pregnancy 11% (n=77)

chronic cardiac 11% (n=84)

immunocompromised 11% (n=77)

morbid obesity 8% (n=57)

renal 5% (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 H1N1 2009

Symptoms Similar Similar

Transmission Same Same

Prevention Same Same

(enhanced droplet)

Severity Similar Similar

Age affected Older (>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?

• http://www.sesamestreet.org/video_player?p_p_lifecycle=0&p_p_id=videoPlayer_WAR_sesameportlets4369&p_p_uid=140598a2-90b4-461f-82d4-53011bdf3849