Influenza Primer: Seasonal and Pandemic

Influenza Primer: Seasonal and Pandemic

October 2, 2009

Dr. Judy MacDonaldDeputy Medical Officer of Health

2www.albertahealthservices.ca

Note

Information and recommendations will change as further information about the epidemiology of pandemic H1N1 and its clinical course is available.


OutlineOutline• Terminology

• Influenza Basics, Pandemic Primer

• Update on H1N1 – epidemiology, characteristics

• Pandemic Planning

– Alberta Health Services – Calgary zone

– Public Health Measures

• Relevance to Post-secondary Institutions


TerminologyTerminology

• pandemic - “pan” = all “demos” = the people

– occurrence of large numbers of cases of a [communicable] disease at the same time around the world

• epidemic - “epi” = upon “demos” = the people

– occurrence of cases of a [communicable] disease in excess of normal expectations

• endemic - “en” = in “demos” = the people

– occurrence of cases of [communicable] disease at a constant background level


TerminologyTerminology

• seasonal influenza is caused by viruses that are already among people

• avian influenza is a contagious

disease in birds caused by

influenza A viruses

• swine influenza is a disease in pigs

caused by influenza A viruses that can also infect humans

• pandemic influenza emerges as a result of major genetic changes in the influenza A virus

Source: WHO avian influenza website


Influenza - the VirusInfluenza - the Virus

• 3 types - A, B and C host of origin (if not human)

A/California/7/2009 (H1N1)

geographic strain year of HA NAtype origin number isolation subtype

B/Malaysia/2506/2004

• epidemics - A and B; pandemics - A only


• spherical RNA virus

• influenza A subtypes classified

by surface antigens:

– haemagglutinin (H) - H1,

H2, H3

– neuraminidase (N) – N1,

N2

• surface antigens unstable,

change constantly

Influenza A – the VirusInfluenza A – the Virus

8 internal genes


Pandemic HistoryPandemic History

• earliest report of epidemic – 412 BC (Hippocrates)• earliest recorded pandemic - 1580

Asia Africa Europe Americas– high death rates (CFR 11% in Rome)

• 17th century – localized epidemics• 18th century – at least 3 pandemics (1729-30;

1732-33; 1781-82)• 19th century – 3 pandemics (1830-31; 1833-34; 1889-

90)


Pandemics of the 20Pandemics of the 20thth Century Century


WHO Pandemic PhasesWHO Pandemic Phases

# confirmed cases >300,000# deaths 3917

As of Sept 20:

12www.albertahealthservices.ca12

As of July 15: 10,156 cases (individual cases not reported after this date)

As of Sept 19: 78 deaths

As of Sept 19:1,467 hospitalized cases, 292 ICU cases

Case count July 15


Influenza tests reported and percentage of tests positive, Canada, by report week, 2008-2009

Apr 26 – May 2Jun 7-13


Canadian Influenza SurveillanceCanadian Influenza Surveillance

97.7% of typed positive influenza A specimens = Pandemic H1N1


H1N1 Laboratory FindingsH1N1 Laboratory Findings

• All pandemic (H1N1) 2009 viruses tested to date are antigenically similar to the A/California/7/2009 vaccine virus

• Pandemic viruses sequenced to date are all closely related to A/California/7/2009 virus with very minor genetic variation (no reassortment with other influenza viruses)

• Serology studies: older adults less vulnerable


FluWatch: www.phac-aspc.gc.ca/fluwatch/09-10/w37_09/index-eng.php


H1N1 EpidemiologyH1N1 Epidemiology

• H1N1 cases:– younger than seasonal cases, especially for those with

severe or fatal illness– Usually mild but some develop severe respiratory failure

(unlike seasonal)• Vulnerable groups:

– Pregnant– Chronic medical conditions (lung, heart disease; diabetes)– Immune compromised– Morbid obesity ?indigenous peoples


FluWatch: www.phac-aspc.gc.ca/fluwatch/09-10/w37_09/index-eng.php

Canadian Epidemiology

Hospitalized cases (n=1467)


Why Worry about this Flu?

• It’s a new strain of influenza virus to which most people have little or no immunity, which may lead to more infections than seen with seasonal influenza

• Though it’s caused mostly mild disease to date, this could change


The Virus is Spread….

Directly:- Person-to-person via infected droplets expelled by coughing

and/or sneezing that are inhaled (up to a two-metre distance).

And Indirectly:

- From contaminated hands and/or surfaces, with subsequent touching of your eyes, nose and/or mouth.

Transmission may be possible over longer distances during aerosol generating medical procedures.


Signs and Symptoms (Influenza-like Illness)

• Acute onset of new cough or change in existing cough, plus 1 or more of the following:

• Fever (≥ 38 C)

• Sore throat

• Joint pain

• Muscle aches

• Severe exhaustion

• Some cases - diarrhea, nausea and/or vomiting

• Few cases progress to severe respiratory illness


Incubation/Infectiousness

Incubation Period:

• Up to 4 days

(seasonal influenza 1-3 days)

Infectious Period (virus shedding):

• In an untreated previously healthy person:

– 1 day prior to, and up to 7 days after onset of symptoms

• In immune compromised or severely ill persons:

– prolonged periods


Prevention – Look after Yourself

• Hand hygiene – diligently and frequently• Respiratory etiquette – cover your cough!!• Stay away from those who are ill• Stay home when you are ill until you are feeling well

enough to participate fully in daily activities– Self Care Strategywww.health.alberta.ca/health-info/influenza-

self-care.html

• Get vaccinated!• Personal preparedness - www.albertahealthservices.ca/files/ns-

2009-08-13-personal-disaster-preparedness-quick-guide.pdf


What about Masks?

Masks – public use

• no evidence of effectiveness in preventing influenza when used in public settings

• may be useful in settings where person is ill with cough and fever

• may give false sense of security to wearer - eyes still exposed; hands can become contaminated


What to do?

Watch for symptoms of influenza-like illness (ILI):

• Sudden onset of new cough +/- fever, with one or more of: sore throat, muscle aches, joint pain, extreme fatigue or weakness

• Vomiting or diarrhea may also be present, especially in young children


What to do if you have ILI? (2)What to do if you have ILI? (2)

• If healthy: – most illness is mild– stay home and recover until symptom-free,

feeling well and able to participate fully– if chest pain, shortness of breath or fever

lasts more than 3 days, go to doctor• If underlying medical condition or pregnant:

– see your doctor right away for early treatment


Diagnosis

Mild disease in a previously healthy person does not require testing!

Testing is only recommended for persons with ILI who:

• Are at higher risk for influenza related complications (pregnant, chronic medical conditions, immune compromised

• Have symptoms severe enough to require admission to hospital


Treatment

• Early treatment with an antiviral (best within 48 hours of onset) is only recommended for those at risk of complications:

• Pregnant women • Persons with chronic cardiopulmonary conditions or other co-

morbid illness

• Persons with severe disease

• ≥ 65 years or older (in outbreak settings)

Prophylaxis is not recommended because of possibility of antiviral resistance


Pandemic Planning - Health SystemPandemic Planning - Health System

overall goals of influenza pandemic preparedness and response are:

• first, to reduce morbidity and mortality

• second, to minimize societal disruption among Albertans by providing access to appropriate prevention measures, care and treatment

Source: Alberta Pandemic Influenza Plan for the Health System, December 2007


AHS - Pandemic Steering CommitteeAHS - Pandemic Steering Committee

Who is involved?

• AHS Executive

• Public Health Leads

• Various Sections and Working Groups:

– ethics, legal, finance, liaison, operations (acute

care, community), public health operations,

logistics, communications, planning (HR, OHS)


Capacity ManagementCapacity Management

• In a pandemic, focus shifts to population survival

• Focus resources on patients with best chance of recovery and survival

• Define Essential Health Services

• With diminishing healthcare (non-monetary) resources, focus of services should be outcomes based


Capacity ManagementCapacity Management

• Addition of Non-Traditional Sites:

– Influenza Assessment Clinics

– Alternate Care Centres/Sites

• Re-deployment of workforce

• Mass Vaccination Clinics

– Challenge: Vaccination of our total population(~1.2 million)


Communication/PreparednessCommunication/Preparedness

• External Web Site (Information, Resources)

• Pandemic Presentations (all levels of the organization, municipalities, private and non-profit agencies)

• Tabletop Exercises

• Personal Preparedness Training and Ethics Presentations


AntiviralsAntivirals

• 55 million doses stockpiled nationally for early treatment (90% oseltamivir, 10% zanamivir)

• Developing mechanisms for delivery within 48 hours of symptom onset

• May not work against pandemic strain; some resistance already reported to oseltamivir


VaccinesVaccines

Primary public health intervention during pandemic to decrease morbidity and mortality

• need to provide safe and effective vaccine program to all Canadians as quickly as possible

• need to allocate, distribute and administer vaccine as rapidly as possible to appropriate groups of people

• must monitor safety and effectiveness of vaccination program

Reference: CPIP, 2006


H1N1 Vaccine

• No cross protection from seasonal influenza vaccine

• Vaccines developed for use in Canada

• Enough vaccine for whole population

• One dose of vaccine needed for most people

• Expected to be available in November 2009


Outstanding questions

• Will disease severity change?• Will pandemic H1N1 virus

replace seasonal influenza strains as predominant circulating influenza virus? – Likely but seasonal

influenza strains also expected to circulate at lower levels (~10-20%)

• Will new risk factors be identified?


What’s the relevance to you?

H1N1 outbreak hits US university – Calgary Herald, Monday, Sept 7, 2009

• 2000 students reporting symptoms of ILI in first 20 days of fall semester

• Blog set up to provide information to students about how to prevent illness and further spread


Are you prepared?

• PHAC - Public Health Guidance for Post Secondary and Boarding Schools regarding the Prevention and Management of Influenza-like-illness (ILI), Including the Pandemic (H1N1) 2009 influenza Virus

www.phac-aspc.gc.ca/alert-alerte/h1n1/hp-ps/psili-eng.php


Resources

• Alberta Health & Wellness

www.health.alberta.ca/health-info/influenza-H1N1.html

• Alberta Health Services www.albertahealthservices.ca

• Public Health Agency of Canada

www.phac-aspc.gc.ca/alert-alerte/h1n1/index-eng.php


Questions??Questions??

Documents

Influenza Primer: Seasonal and Pandemic