Influenza

Timothy Wiemken, PhD MPH CICAssistant Professor

Division of Infectious DiseasesUniversity of Louisville

tim.wiemken@louisville.edu

Overview

• The influenza virus• Influenza transmission• Available Vaccines• Vaccine Efficacy/Effectiveness

The Influenza Virus

The Influenza Virus

Three types of influenza viruses

A

B

C

The Influenza Virus

Three types of influenza viruses

Influenza A Separated into serotypes using

Hemagglutinin and Neuraminidase

16 different H’s9 different N’s

Influenza A Strains

1918-19

Severe

1957-58

Severe

1968-69

Moderate

1977-78

Mild

2009- 12

H1N1

Mild

1918 1950 1960 1970 1980 2000 2009 2012

H2N2 H3N2 2009 H1N1

The Influenza Virus

2012-

H3N2

H1N1

Influenza A Strains

1918-19

Severe

1957-58

Severe

1968-69

Moderate

1977-78

Mild

2009- 12

H1N1

Mild

1918 1950 1960 1970 1980 2000 2009 2012

H2N2 H3N2 2009 H1N1

The Influenza Virus

2012-

H3N2

H1N1

Influenza A Strains

1918-19

Severe

1957-58

Severe

1968-69

Moderate

1977-78

Mild

2009- 12

H1N1

Mild

1918 1950 1960 1970 1980 2000 2009 2012

H2N2 H3N2 2009 H1N1

The Influenza Virus

2012-

H3N2

H1N1

Influenza A Strains

1918-19

Severe

1957-58

Severe

1968-69

Moderate

1977-78

Mild

2009- 12

H1N1

Mild

1918 1950 1960 1970 1980 2000 2009 2012

H2N2 H3N2 2009 H1N1

The Influenza Virus

2012-

H3N2

H1N1

Influenza A Strains

1918-19

Severe

1957-58

Severe

1968-69

Moderate

1977-78

Mild

2009- 12

H1N1

Mild

1918 1950 1960 1970 1980 2000 2009 2012

H2N2 H3N2 2009 H1N1

The Influenza Virus

2012-

H3N2

H1N1

The Influenza Virus

6 19 33

12984

190

321

431

686

1195

65

358

0

200

400

600

800

1000

1200

Age group (yrs)

Pe

r 1

00

,00

0 p

op

ula

tio

n

Influenza-related mortality Influenza-related hospitalizations

65-69 70-74 75-79 80-84 ≥8550-64

The Influenza Virus

Naming of influenza viruses

1. Antigenic type (A, B, C)2. Host of Origin (unless human)3. Geographical Origin4. Strain Number5. Year of Isolation6. For A’s, H and N antigens

The Influenza Virus

A/Perth/16/2009 (H3N2)

Influenza A

The Influenza Virus

A/Perth/16/2009 (H3N2)

Influenza A

No Host – Human!

The Influenza Virus

A/Perth/16/2009 (H3N2)

Influenza A

No Host – Human!

From Perth

The Influenza Virus

A/Perth/16/2009 (H3N2)

Influenza A

No Host – Human!

From Perth

16th strain

The Influenza Virus

A/Perth/16/2009 (H3N2)

Influenza A

No Host – Human!

From Perth

16th strain

First isolated in 2009

The Influenza Virus

A/Perth/16/2009 (H3N2)

Influenza A

No Host – Human!

From Perth

16th strain

First isolated in 2009

Since it is Flu A, need H and N type, H3N2

The Influenza Virus

• B’s are named the same but don’t have subtypes

• Lineages are Victoria or Yamagata

The Influenza Virus

Overview

• The influenza virus• Influenza transmission• Available Vaccines• Vaccine Efficacy/Effectiveness

Influenza Transmission

Droplet

Contact

Influenza Transmission

Overview

• The influenza virus• Influenza transmission• Available Vaccines• Vaccine Efficacy/Effectiveness

Available Vaccines

• Trivalent (2 A’s, 1 B) Intramuscular• Trivalent Intramuscular High Dose• Trivalent Intradermal• Quadrivalent (2A’s, 2 B’s)

Intramuscular• Quadrivalent Intranasal

Available Vaccines

• What should I use?• When should I use it?

Available Vaccines

• CDC says whatever.

Available Vaccines

• Kids/around kids = quadrivalent– Intranasal (quadrivalent)

• HCW = quadrivalent• Comorbidities = quadrivalent• ≥65 = high dose

Available Vaccines

• Kids/around kids = quadrivalent– Intranasal (quadrivalent)

• HCW = quadrivalent• Comorbidities = quadrivalent• ≥65 = high dose

In other words, don’t waste the quadrivalent on creepers.

Available Vaccines

Overview

• The influenza virus• Influenza transmission• Available Vaccines• Vaccine Efficacy/Effectiveness

Vaccine Efficacy/Effectiveness

Efficacy: Did it work in the clinical trial versus placebo?

Effectiveness: Does it work in real life?

The numbers vary based on the outcome under study.

Vaccine Efficacy/Effectiveness

• Trivalent (2 A’s, 1 B) Intramuscular

Vaccine Efficacy/Effectiveness

• Trivalent (2 A’s, 1 B) Intramuscular• Effectiveness for preventing ARI due

to Flu

Age Group Subtype Vaccine Effectiveness (95% CI)

Overall All 56% (47%-63%)

Overall H3N2 47% (35%-58%)

Overall B 67% (51%-78%)

Vaccine Efficacy/Effectiveness

• Trivalent (2 A’s, 1 B) Intramuscular• I heard it was 9% though?

Vaccine Efficacy/Effectiveness

• Trivalent (2 A’s, 1 B) Intramuscular• I heard it was 9% though?

• For H3N2 only… for those over 65…– Effectiveness 9%– 95% CI: -84% to 55%– ~200 people only!!!

Available Vaccines

Pop quiz

How effective is the flu vaccine if you don’t receive it?

Vaccine Efficacy/Effectiveness

Influenza B effectiveness… historicallySeason % B % Yamagata % Victoria Vaccine

2000–2001 46 100 0 Yamagata

2001–2002 13 23 77 Yamagata

2002–2003 43 0.4 99.6 Victoria

2003–2004 1 93 7 Victoria

2004–2005 25 74 26 Yamagata

2005–2006 19 22 78 Yamagata

2006–2007 21 24 77 Victoria

2007–2008 29 98 2 Victoria

2008–2009 33 17 83 Yamagata

2009–2010 0.2 12 88 Victoria

2010–2011 30 6 94 Victoria

2011–2012 14 51 49 Victoria

Vaccine Efficacy/Effectiveness

• Quadrivalent (2 A’s, 2 B) Intramuscular

Overview

• The influenza virus• Influenza transmission• Available Vaccines• Vaccine Efficacy/Effectiveness