H1N1 Update

COL Michael Sigmon, MD MPHPublic Health Emergency Officer

Joint Task Force- Homeland Defense Hawaii

What is a Pandemic?• A pandemic is a global disease outbreak. An influenza

pandemic occurs when a new influenza A virus emerges for which there is little or no immunity in the human population, begins to cause serious illness and then spreads easily person-to-person worldwide.

• Three conditions for a pandemic:

1) The virus must be novel and unknown to man; AND

2) It must be capable of causing severe disease in humans; AND

3) It must be capable of being passed easily among humans.

WHO Pandemic Phase H1N1

World Health Organization’sChief Concern

• In past pandemics, influenza viruses have needed more than six months to spread as widely as the new H1N1 virus has spread in less than six weeks.

• Pandemic (H1N1) 2009 briefing note 3 (revised)

• Changes in reporting requirements for pandemic (H1N1) 2009 virus infection

• 16 JULY 2009 | GENEVA

1918 Pandemic- “Spanish Influenza”

Overwhelming Health and Social Systems

Age Distribution remains a concern

CDC Pandemic Severity Index

Some Current Case Fatality Ratios for Novel H1N1

WHO World Wide: .12%

(3486 deaths/296471 cases)

WHO West Pacific/Southeast Asia: .04%

(337 deaths/76348 cases)

Hawaii (media reports) .40%

(4 deaths/1000 cases)

CDC Surveillance as of last week

Significant Increase in ILI Activity

Seasonal Influenza

• Kills 36,000 Americans yearly

• Predominant strain H3N2

• Flu shot 80% effective and best countermeasure

• Immunization important:– Treat a serious illness

– Keep beneficiaries from becoming viral “mixing bowls”

– Red flag if influenza-like illness appears in a highly vaccinated population

Seasonal influenza highly resistant to antivirals!

Novel H1N1 Influenza

15

NA inhibitors Mechanism of Action

Oseltamivir/Zanamivir

NAI prevent virus release and spread in respiratory tract

H1N1 Influenza Vaccine

H1N1 Vaccine ready soon

Good News: Vaccine will start to be made

available in early October.

Rapid approval since it is not experimental,

Non-adjuvanted

One dose of vaccine only*

Bad news: 40 million doses for entire country distributed through state per capita basis. Hawaii is .4% of US population.

ACIP Priorities

• pregnant women,

• persons who live with or provide care for infants aged <6 months (e.g., parents, siblings, and daycare providers),

• health-care and emergency medical services personnel,

• persons aged 6 months--24 years, and

• persons aged 25--64 years who have medical conditions that put them at higher risk for influenza-related complications.

• These five target groups comprise an estimated 159 million

persons in the United States.

Consider Non-pharmacologic Measures

• .

• Public health measures– Likely to work if implemented– Handwashing (gels), masks, social distancing– Stay at home when ill

• Quarantine and “Protective Sequestration”– Some successes in 1918: relies on self-reliant communities– May disrupt essential services more than disease spread

• Reason: asymptomatic viral shedding 24-48 h prior to becoming ill

Community-based interventions

1. Delay disease transmission and outbreak peak

2. Decompress peak burden on healthcare infrastructure

3. Diminish overall cases and health impacts

Daily

Cases

#1

#2

#3

Days since First Case

Pandemic outbreak:No intervention

Pandemic outbreak:With intervention

San Francisco Naval Training Station Experience

• Population: Approx. 6,000

• Pop. Density: 33,103 persons/sq. mi.

• Geographical : San Francisco Bay island (116 acres); no bridges (1918) to land (boat ferry only)

NPI-Implementation

• Protective sequestration

• Face masks for personnel

• Daily inspection of sailors

• Prevention of overcrowding

• Nose/throat sprays (10% argyrol)

• Isolation of suspected cases

Interventions

10 March 2007

San Francisco Naval Training Station Success

• Influenza Cases: 0 during period of protective sequestration; 25 cases after NPI lifted 11/21/18

• Influenza Deaths: 0 during period of protective sequestration; 3 influenza + 2 pneumonia after

• First Reported Case: Dec. 6, 1918

Summary

• H1N1 is now producing illness equivalent to peak seasonal influenza, but mortality and morbidity are within baseline

• H1N1 has different target population. Pregnant, school age children, vulnerable under 50.

• H1N1 vaccination program is also novel for 2009

• Non-pharmacologic measures work

For Further Information

• www.flu.gov

• http://fhp.osd.mil/aiWatchboard/

• http://www.who.int/csr/disease/swineflu/en/

• http://h1n1.nejm.org/

Questions?