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
SEX
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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
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