Influenza: From Basics to Pandemics

1. Influenza: From Basics to Pandemics

2. Why Worry? Why Plan? • Influenza is Serious! • Annual deaths: 36,000 • Hospitalizations: >200,000 • Who is at greatest risk for serious complications? • Persons 65 and older • Persons with chronic diseases • Infants • Pregnant women • Nursing home residents

3. Influenza= Flu • Respiratory infection • Rapid onset of Fever, Chills, Body aches, Sore throat, Non-productive cough, Runny nose, Headache • Takes 1- 5 days from exposure to beginning of symptoms • Contagious maximum 1-2 days before to 4-5 days after onset of symptoms • Peak usually occurs December through March in North America

4. Influenza Virus: How it spreads • Close contact (<6 feet) with sick person who is coughing or sneezing by way of droplets OR • Touching a surface contaminated by respiratory secretions and getting the virus into mouth, nose or eyes.

5. Influenza Epidemic Pattern • Epidemic: Higher than normal number of cases of a disease in a community • Also called “outbreak” • Abrupt onset in a community: overall attack rate 10-20% • Sharp peak in 2- 3 weeks, lasts about 5-6 weeks

6. Influenza Epidemic Pattern • First sign: Increased # children with febrile respiratory illness • Followed by: increased hospitalization rate for pneumonia/COPD/CHF/croup • Absenteeism a late indicator

7. Influenza background • Flu strains typically found in many mammals • Birds and swine common hosts for what ultimately become human flu viruses • Flu hosts usually develop an immunity to the virus after infection

8. How does the virus survive? • Minor mutation in flu virus is referred to as drift. • A much bigger change is referred to as a shift • Shift: Major change = new subtype = Pandemic potential • Pandemic – An epidemic that spreads around the world

9. Influenza types • Type A(Party Girls) • Animals and humans • More versatile, more virulent • Epidemics and pandemics • All ages • Type B (DAR) • Humans only • Milder epidemics • Primarily affects children

10. Key Influenza A Viral Features Two surface glycoproteins (major antigens) Hemagglutinin (HA) • Site of attachment to host cells • Antibody to HA is protective Neuraminadase (NA) • Helps release virions from cells • Antibody to NA can help modify disease severity HA NA

11. The Pandemic Influenza Cycle • Rapid transmission worldwide • Multiple waves of disease over a 18-24 month period • Occurrence of cases outside usual season • High attack rate and high death rate • All age groups, especially young adults • Cycles every 10-40 years • Last pandemic was mild-1968

12. How does the virus survive? • Minor mutation in antigens of flu virus is referred to as drift. • A much bigger immunologic change (mutation) is referred to as a shift • Shift: Major change = new/novel subtype = Pandemic potential • Pandemic – an infectious disease occurring over a wide geographic area targeting a high percentage of the population

13. DIRECT - 1918 Mechanisms of Antigenic Shift Non-human virus Human virus Reassortant Virus – 1957, 1968

14. The Pandemic Influenza Cycle • Rapid transmission with worldwide outbreaks; multiple waves of disease over a 18-24 month period • Occurrence of cases outside the usual season • High attack rate for all age groups, with high mortality rates, esp for young adults • Cycles 10-40 years. Last pandemic was mild, 1968

15. Credit: US National Museum of Health and Medicine Influenza Pandemics in the 20th Century 1918: “Spanish Flu” 1957: “Asian Flu” 1968: “Hong Kong Flu” A(H1N1) A(H2N2) A(H3N2) 20-40 m deaths 675,000 US deaths 1-4 m deaths 70,000 US deaths 1-4 m deaths 34,000 US deaths

16. Impact of Past Influenza Pandemics/Antigenic Shifts

17. The social and medical importance of the 1918-1919 influenza pandemic cannot be overemphasized • About half of the 2 billion people living on earth in 1918 became infected • At least 20 million people died

18. 1918 Spanish Flu: United States • 20 million flu cases were reported and almost ½ million people died “It is impossible to imagine the social misery and dislocation implicit in these dry statistics.” America’s Forgotten Pandemic,Alfred Crosby

19. H5N1 “Avian” flu • The current strain of avian flu, H5N1, represents a major shift • When the major shift “waits” 50-75 years: • Community has very little or no immunity/protection • Entire population is a ripe target

20. Current outbreaks for H5N1 Avian Flu in poultry and birds are largest ever documented Duration of outbreak creates potential for genetic change that could result in person-to-person transmission

21. Nations With Confirmed Cases H5N1 Avian Influenza(July 7, 2006)

22. Avian Influenza A Viruses • Wild waterfowl are natural reservoir • Infect respiratory and gastrointestinal tracts of birds • Usually do not cause disease • Genetic re-assortment is frequent • Viruses are present in respiratory secretions, feces • Can survive at low temperatures and low humidity for days to weeks, and in water

25. H5N1 in Humans –2003-2006 • As of June, 2006: 256 cases, 152 deaths • Ten countries • Millions have been exposed to poultry • 50% cases in persons <20 years old • 90% cases <40 years old • Sporadic, with occasional clusters • All lived in countries with poultry outbreaks • Most had touched or handled sick poultry • Few cases of probable, limited human-to-human transmission

26. Global Status of Current Pandemic Threat • World Health Organization (WHO) defines 3 major periods (broken into 6 phases) of increasing human infection with new flu virus: • Interpandemic (no human infection) • Pandemic Alert (limited human infection) • Pandemic (widespread human infection) • Presently at Pandemic Alert (Phase 3) • “Isolated human infections with a novel influenza strain [H5N1] with no (or rare) person-to-person transmission”.

27. “The pandemic clock is ticking, we just don’t know what time it is”

28. Assumptions About Disease Transmission • No one immune to virus • 1 out of every 3 people will become ill • People may be contagious up to 24 hours before they know they are sick • Most will become ill 2 days (range 1-10) after exposure • People are most contagious the first 2 days of illness • Sick children are more contagious than adults • On average, each ill person can infect 2 or 3 others (if no precautions are taken)

29. Social and Economic Impact Assumptions • Absenteeism • At the peak of a 6-8 week wave, ~40% of employees may be absent • Illness • Caring for sick family member • Fear • Hospital demands • Estimated >25% more patients than normal needing hospitalization • Hospitals will not be able to take everyone they normally would!

30. Federal or other outside volunteers and resources? • Volunteers will be needed in their own communities • Communities should plan to respond with their own resources, not rely on outside help

31. HHS Estimated Medical Burdenin Tennessee (Pop: 6 million) *HHS Recommends that states plan for severe scenario

32. Estimated Medical Burden in Knox County

33. HHS Assumptions: Objectives of Pandemic Planning & Response • Primary objective: • Minimize sickness and death • Secondary objectives: • Preserve functional society • Minimize economic disruption • There is not complete consensus on the proper order of these assumptions!

34. Surveillance: • Traditional responsibility of Department of Health • Syndromic Surveillance: Monitor 911 calls, emergency department visits, doctor visits, and school absenteeism • Sentinel health care providers: Testing and active surveillance for patients with ILI • CDC planning additional national surveillance activities

35. Disease Control:Early Stage • Initial objective: slow spread of disease • Isolate sick patients • Quarantine exposed healthy persons. • Housing, health care, food, psychological, spiritual, needs must be met • Legal measures possible but will rely on voluntary cooperation

36. Once beyond initial cases, shift strategy to “Stay home when you are sick”

37. Disease Control: Social Distancing • Once pandemic begins in US, gatherings of >10,000 people subject to cancellation • During local waves: Suspend discretionary public gatherings of >100

38. School and Daycare Closure • Key to slowing spread is to disrupt nodes of intense transmission • Preschool through 12th grade are such nodes • Attack rates of 40% possible in schools during ordinary flu season • Pre-emptive school/large daycare closure is central component of proposed federal strategy

39. School and Daycare Closure • Key to slowing spread is to disrupt nodes of intense transmission • Preschool through 12th grade are such nodes (Attack rates of 40% possible in schools during ordinary flu season) • Pre-emptive school/large daycare closure is central component of proposed federal strategy

40. Infection Control:“Cover Your Cough” • “Respiratory hygiene”, “Cough etiquette”, “Good health manners”

41. Infection ControlAssumptions • Survival @ 82oF, 35-49% humidity (longer if lower temp, lower humidity) • 48h on hard non-porous surfaces • 8-12h on cloth, paper, tissue • Susceptible to EPA registered disinfectants • Transmission: Droplet- surgical masks protective

42. Infection ControlAssumptions • Airborne transmission (less common, but much more infective: 10-100 x vs. droplets). Surgical masks NOT protective • Aerosol-generating procedures (e.g., intubation, suctioning, nebulizer treatment, bronchoscopy, intubation, BiPAP, CPAP): N95 respirators should be used

43. Production minimum 6 month process: Process requires eggs (93 million!) but virus is lethal to birds Unlikely to be available before 1st pandemic wave HHS priority groups Military and Vaccine manufacturers Healthcare workers with direct patient care Persons at highest risk for complications Two doses needed for protection What About Vaccine?

44. Tamiflu Anti-viral agent, currently in short supply Could be used in one area of world to contain first human outbreak Resistance described Should be used within 48 of infection Unlikely to markedly affect course of pandemic Tamiflu ≠ Preparedness What About Antivirals?

45. Vaccine/Antiviral Distribution • Prioritization of personnel : based on level of patient contact • Vaccine will be administered by public health personnel over months • Prioritization determined by Feds and may change

46. Guidance for Planning Because resources will be limited… Contingency planning should include: • Planning for absenteeism: ~40% • Hygiene products and education in the workplace • Supply shortages • Home offices for critical personnel • Sick leave policies compatible with state recommendations

47. Internal and External Communication networks • Detailed communications plans needed: • Internal- Ensure employees know panflu policy, communications plan, their specific role, esp in surge capacity • External- POC with Health Department • Info via KCHD website, Broadcast FAX, Email, Media • Coordinate with like organizations to develop/coordinate emergency plans • Communicate with other facilities affected by yours

48. Infection Control: Education • Signage to educate personnel and patients • Adequacy of surgical masks for patient contact not involving aerosolization procedures • Possibility of using surgical masks over reusable N95s as well as goggles/face shields for high-risk procedures • Establishing regularly scheduled environmental cleaning

49. Infection Control:Using PPE Follow protocol for donning and removing PPE • Provide tissues & instructions when to use them: proper disposal; importance of hand- hygiene Provide hand hygiene materials (>60% alcohol)

50. Surveillance for those at work • Develop screening for employees with flu-like symptoms • Develop sick leave policy specific for panflu: liberal and non-punitive • Determine when ill employee may return to work