2009 Influenza A(H1N1) – Human Swine Flu Is this the pandemic? Allison McGeer, MSc, MD, FRCPC Mount Sinai Hospital University of Toronto

Nasal Congestion Sore Throat Muscle Pains Headache Cough Malaise Infectious Clinical Characteristics of Seasonal Influenza Infection Days After Onset 0 1 2 3 4 5 6 7 8 Nöel GE. Life-threatening “flu”? Can J Diagnosis 1999;Mar Fever

Be an influenza virus, see the world

Changes in Influenza Viruses Antigenic drift (continuous mutation) minor changes in A & B strains, s ame subtype every year while virus is in humans Antigenic shift (recombination with non-human viruses) produce new subtype with changed H and/or N population has no immunity to this new virus

Antigenic drift (continuous mutation)

minor changes in A & B strains, s ame subtype

every year while virus is in humans

Antigenic shift (recombination with non-human viruses)

produce new subtype with changed H and/or N

population has no immunity to this new virus

Human virus Reassortant virus Avian virus 16 HAs 9 NAs Mechanisms of Antigenic Shift Swine virus

2009 H1N1 influenza A April 10-15 Mexican authorities recognize increase in acute respiratory disease/pneumonia, especially in young adults April 17 US recognizes new influenza strain, mostly derived from pigs (a “swine” flu), in two unrelated children in California

April 10-15

Mexican authorities recognize increase in acute respiratory disease/pneumonia, especially in young adults

April 17

US recognizes new influenza strain, mostly derived from pigs (a “swine” flu), in two unrelated children in California

2009 A(H1N1) – Human Swine flu Disease Symptoms – typical influenza Fever (>90%) Cough (>90%) “ Prostration” Nasal congestion Sore throat (66%) Diarrhea (25%) Vomiting (25%) Provisos Almost certainly, milder disease occurs More severe disease likely won’t present “typically”

Symptoms – typical influenza

Fever (>90%)

Cough (>90%)

“ Prostration”

Nasal congestion

Sore throat (66%)

Diarrhea (25%)

Vomiting (25%)

Provisos

Almost certainly, milder disease occurs

More severe disease likely won’t present “typically”

How severe is it? WHO totals: 61 deaths / 5728 cases Case fatality rate=1% 2009 A(H1N1) – Human Swine flu Disease

How severe is it?

WHO totals: 61 deaths / 5728 cases

Case fatality rate=1%

How severe is it? WHO totals: 61 deaths / 5728 cases Case fatality rate=1% WHO Rapid Pandemic Assessment Collaboration (Science 11 May) Case fatality rate: 0.4% (0.3-1.5%) 0 (U95%CL 0.6%) 2009 A(H1N1) – Human Swine flu Disease

How severe is it?

WHO totals: 61 deaths / 5728 cases

Case fatality rate=1%

WHO Rapid Pandemic Assessment Collaboration (Science 11 May)

Case fatality rate: 0.4% (0.3-1.5%)

0 (U95%CL 0.6%)

No – not quite “humanized” Yes – and “first wave” will start in the next few weeks Yes – but “first wave” won’t start until sometime in the fall 2009 A(H1N1) – Human Swine flu Is it the next pandemic?

No – not quite “humanized”

Yes – and “first wave” will start in the next few weeks

Yes – but “first wave” won’t start until sometime in the fall

So, what are we doing in hospitals? Brushing off our pandemic plans, and activating phase 5 Filling in the gaps Recognizing that the pressure in ICUs may be less than anticipated, but the workload in ED and primary may be higher

Brushing off our pandemic plans, and activating phase 5

Filling in the gaps

Recognizing that the pressure in ICUs may be less than anticipated, but the workload in ED and primary may be higher