2009 Influenza A(H1N1) – Human Swine FluIs this the pandemic?

2009 Influenza A(H1N1) – Human Swine FluIs this the pandemic?

Allison McGeer, MSc, MD, FRCPC

Mount Sinai Hospital

University of Toronto

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 InfectionClinical Characteristics of Seasonal Influenza InfectionClinical Characteristics of Seasonal Influenza InfectionClinical Characteristics of Seasonal Influenza Infection

Days After Onset 0 1 2 3 4 5 6 7 8

Nöel GE. Life-threatening “flu”? Nöel GE. Life-threatening “flu”? Can J DiagnosisCan J Diagnosis 1999;Mar 1999;Mar

Fever

Be an influenza virus, see the world

Changes in Influenza VirusesChanges in Influenza VirusesChanges in Influenza VirusesChanges in Influenza Viruses

Antigenic drift (continuous mutation) – minor changes in A & B strains, same 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, same 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

HumanHuman virusvirus

ReassortantReassortantvirusvirus

AvianAvianvirusvirus

16 HAs16 HAs 9 NAs9 NAs

Mechanisms of Antigenic Shift

SwineSwinevirusvirus

2009 H1N1 influenza A2009 H1N1 influenza A2009 H1N1 influenza A2009 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 flu2009 A(H1N1) – Human Swine fluDiseaseDisease2009 A(H1N1) – Human Swine flu2009 A(H1N1) – Human Swine fluDiseaseDisease

Symptoms – typical influenza Fever (>90%)

Cough (>90%) “Prostration”

Nasal congestion Sore throat (66%)

Diarrhea (25%) Vomiting (25%)

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”

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%

How severe is it?– WHO totals: 61 deaths / 5728 cases

Case fatality rate=1%

2009 A(H1N1) – Human Swine flu2009 A(H1N1) – Human Swine fluDiseaseDisease2009 A(H1N1) – Human Swine flu2009 A(H1N1) – Human Swine fluDiseaseDisease

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%)

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 flu2009 A(H1N1) – Human Swine fluDiseaseDisease2009 A(H1N1) – Human Swine flu2009 A(H1N1) – Human Swine fluDiseaseDisease

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

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 flu2009 A(H1N1) – Human Swine fluIs it the next pandemic?Is it the next pandemic?2009 A(H1N1) – Human Swine flu2009 A(H1N1) – Human Swine fluIs it the next pandemic?Is it the next pandemic?

So, what are we doing in hospitals?So, what are we doing in hospitals?So, what are we doing in hospitals?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