Control of infection in the community

Darina OFlanaganDirector

Health Protection Surveillance Centre

Learning objectivesImportance of Surveillance/ Epidemic IntelligenceNew International Health RegulationsClusters of unusual diseasesIceberg conceptImportance of reporting culturePrimary prevention of infection in the community: VaccinationSecondary Prevention ChemoprophylaxisHaemophilus influenzae meningitisInvasive Meningococcal disease, Invasive Group A Strep, TBOutbreak Management in the CommunityFoodborne Outbreaks done with Dr McNamaraLegionnaires DiseaseResponding to Emerging Diseases: Pandemic Influenza

Definition of public health surveillanceThe ongoing systematic collection and analysis of data and the provision of information which leads to action being taken to prevent and control a disease, usually one of an infectious nature.

Risk Assessment vs. Risk ManagementRisk assessmentRisk managementMonitor informationImplement control measuresAssess signalInvestigate PH alertDisseminate informationRisk communicationRisk monitoring

Epidemic Intelligence Framework Important for new International Health RegulationsReportDataCapture Filter VerifyCollect Analyse InterpretAssessInvestigateSignalEvent monitoringEvent-based componentIndicator-based componentControl measuresPublic health AlertEWRSRapid inquiriesE-AlertsIHREpi bulletinWEBDisseminateSurveillance systems

Epidemic IntelligenceDefinition Epidemic intelligence is the process to detect, verify, analyze, assess and investigate signals that may represent a threat to public health. It encompasses all activities related to early warning surveillance functions but also signal assessments and outbreak investigation.

Indicator-based EI componentHealthcare settingsIdentified risksMandatory notificationLaboratory surveillanceEmerging risksSyndromic surveillanceMortality monitoringHealth care activity monitoringPrescription monitoringPoison centres

Risk monitoringEvent-based surveillanceDomesticMedia monitoringEI focal pointsInternationalInformation scanning tools (GPhin, MedISys)Distribution lists/NetworksPROMED WHO-OVLInternational agencies

Event-based surveillanceInfo scanning tools - GPhin

Outbreak detectionMay 2000 ScotlandSevere soft tissue abscesses systemic illness and death in IDUEU rapid alert issuedSurveillance set up in A & EIrish outbreak identified22 cases, 8 deathsClostridium novyii identifedNew methadone clinics offeredMessages to IDU not to muscle popAttend early if any abscess

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National Disease Surveillance Centre

Unusual clusters or changing patterns of illness (Outbreak)

A cluster (outbreak) of infection or food-borne illness may be defined as two or more linked cases of the same illness or the situation where the observed number of cases exceeds the expected number. Clusters (outbreaks) may be confined to some of the members of one family or may be more widespread and involve cases either locally, nationally or internationally. Notifiers are also required to notify changing patterns of illness that may be of public health concern, including those that may indicate a bioterrorist related outbreak.

ExposedClinical specimenDisease Pos. specimenInfectedSeek medical attentionReportSurveillance:you see what you look atLaboratory-based surveillanceClinically-based surveillanceSerological surveyCommunity-based surveillance

Acute Gastroenteritis Survey* North and SouthFrequency of IID4.5% per 4 week period9000 new episodes per day3.2M episodes per year

Days of illness 12.6M per year

GP Consultations 3000 per day (7.5% lab spec -2% ill)1.1M per year

Working Days lost 1.5M per yearLoss of Earnings173M per yearSource: FSPB. Acute Gastroenteritis in Ireland, North and South, FSPB, Dublin: 2003

Invasive Meningococcal Disease(IMD)A highly succesful example of primary prevention of infectious disease in the community

IMD in Ireland 1999- 2004Monthly number of casesOct 2000 Men C vaccine

Invasive Haemophilus influenzae type b (Hib) diseaseAn example of surveillance data being used to influence the childhood immunisation schedule

Quarterly immunisation uptake rates at 24 months in Ireland

Invasive Hib in Ireland 1987- 2005

Summary Hib in IrelandIn 2005Incidence of invasive Hib disease increased in

Chemoprophylaxis

Chemoprophylaxis- Meningococcal AimEliminate carriage from network of close contacts*Prevent further cases among susceptible close contactsSaliva inhibitory to meningococcal growthSecondary cases are rare less than 3% of all cases are considered secondary cases. Risk of disease is highest amongst household contactsHighest risk in the 1st week, and falls over next 2-3 months. With chemoprophylaxis this is extended up to 6 months Attack rate x 500-1000 = 1% households in 1st month (1 in 300 secondary contacts)Secondary cases in crches etc: v. rare, 4 cases over 3 years in population 56 million. (1 in 1500 for crche, 1 in 1800 for primary school and 1 in 33000 for secondary school. A randomised control trial is impossible.)

Chemoprophylaxis-Meningococcal For index patient as soon as can tolerate oral medication (unless treated with ceftriaxone if cefotaxime still need chemo)For close contactsIf contact within 7 days prior to the onset (incubation 3-5 days;) Eligible close contacts are household contact: shared living/sleeping accommodation; includes baby mindersmouth kissing contact (usually close contact)Gave mouth to mouth resuscitation (1 in 100,000, wear masks!)in same nursery/crche : where nature/duration of contact is similar to to that for household contacts

Chemoprophylaxis- School setting (1) School contactsProphylaxis not indicated for sporadic cases, but give adviceIf 2 or more cases in the same class in the same term give to class members and teachers

Chemoprophylaxis- School setting (2) in different classes management depends on factors such asinterval between cases, size of the contact group, carriage rate in the school, whether due to vaccine preventable strain,incidence of the disease in the community ? community outbreakthe degree of public concern

ChemoprophylaxisNot recommended routinely on public transport e.g. bus and trainSpecial consideration to party esp with pre-school children present - if decide to give give to all adults and children Special consideration to members of extended family where overcrowding or adverse living conditions Simultaneous administration is ideal but if someone missed then give up to within a month

Chemoprophylaxis usedRifampicinFrequently used, oral (two days)CiprofloxacinBecoming more frequently used (one dose)CeftriaxoneOften used for pregnant contactsIM injection

Chemoprophylaxis - Hib diseaseRifampicin recommended for 4 days4 days needed to eradicate carriage (more days than for meningo) 20mg/kg/day (up to a max of 600mg daily) once daily for four daysRecent recommendations from UK recommend rifampicin to all household members if at risk individuals in household (regardless of immunisation status) i.e. Children < 4 years in householdImmunocompromised individual In crche or playgroupTwo or more cases in 120 day period, offer to all room contacts (children and adults)

Invasive Group A Strep iGASMost GAS infections mild such as strep throat or impetigo. Rare occasions can become invasive e.g. necrotising fasciitis or Streptococcal toxic shock syndromeClose contacts should receive chemo (oral penicillin) if symptoms suggestive of localised GAS infectionMother and baby if either develops iGAS in the neonatal periodOther contacts should be given leaflet and warned to look out for symptoms for 30 days after diagnosis in the index case see leaflet on www.hpsc.ie

TB

TB notification rates per 100,000 population, Europe, 2003

National Notifications of Tuberculosis 1952 - 2003BCG introduced early 50sSource: DoHC 1952-1997, HPSC 1998-2003

What do we want to do? Stop people getting TBHow?Find people with infectious TB as soon as possible and treat themFind their contacts and examine them to ensure that they haveNot got TBAre not developing TB (TB infection / latent TB)Find people who have a high risk of having latent TB, test them and if positive for TB, treat them with chemoprophylaxis (new entrant screening)BCG

Incidence rate per million population of legionnaires disease in various European countries, 2004

Chart1

23.8

21

19.9

19

14.8

12.1

6.3

5.8

2.9

1

0.4

1.1

Country

Rate per million

Sheet1

SpainCroatiaFranceDenmarkNetherlandsSwedenScotlandE&WNIIrelandPolandRomania

23.82119.91914.812.16.35.82.910.41.1

Sheet1

Country

Rate per million

Sheet2

Sheet3

Incidence of Legionnaires DiseaseLess than 5% of cases are notified through passive surveillance (Marston,1997)Legionella causes 2 to 16% of community acquired pneumonia cases in industrialised countries (Bohte,1995)Legionella causes 14 to 37% of severe cases of community acquired pneumonia, with associated mortality in excess of 25% (Hubbard,1993)

Case Legionnaires in Ireland 1999-2004 Of 30 cases notified in this time period 11 were community acquired (36.8%)2 was nosocomial (6.6%) (Laboratory confirmed case that occurs in a patient who was in hospital for all 10 days before onset of symptoms.)17 were travel acquired (56.6%) (A case who in the ten days before onset of illness stayed at/visited an accommodation site reported to EWGLI)Countries acquired included: France, Ireland, Italy, Malta, Mexico, Portugal, Spain, Tunisia and USA. Male:female ratio is 2.2:1Age Range between 19-80 years and median age is 53 years

Diagnosis and follow upNotify MOHCheck 14 day diaryNotify EHO who will sample water at hotels +/- domestic houses

Emerging and re-emerging zoonoses, 19962004

SARS in Ireland

Notifiable since March 200350 cases investigated 17 cases in total identified (Case Definition)1 Probable Case 16 Suspect Cases 60% male, Age Range: 1-77 years; Median: 45 years, Mean: 43 years Distribution of casesERHA (12); NWHB (2); SHB (1); MHB(1);WHB-Probable Case (1)8 with alternative diagnosisInfluenza A (2), Influenza B (1)RSV (1), Acute Bacterial Pneumonia (2)Exacerbation of COPD (1)Atypical Pneumonia (1)-No organism isolated.

Influenza report available weekly at www.hpsc.ieILI rate per 100,000 population and the number of positive influenza specimens detected by the NVRL during the 2000/2001, 2001/2002, 2002/2003, 2003/2004 & 2004/2005 seasons, summer 2005 and the 2005/2006 season.

Fig 2

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&A

Page &P

Influenza A

Influenza B

ILI Rate

Season

ILI rate per 100,000 population

Number of positive specimens

Data

YearWeek NoFlu A from dbInfluenza AInfluenza BILI RateSeason

2000402018.7Please note that in order to present flu positive specimens as overlapping bars, flu B specimens need to be added to flu As. Ask Lisa D/Kate H if you need more information.

2000410028.1

2000420017.6

2000430022.2

2000440119.2

2000450024.6

2000460017.6

2000470015.1

2000482012.7

2000491010

2000502024.6

2000513030.7

2000521020.1

200113118.6

200125023.4

200138142.32000/2001

200149256.2

200057030

200169477.3

200171711108.9

200181410122.9

20019013104.6

200110141372

2001110111.3

2001120957.6

2001130366.1

2001140733.4

2001150626.9

2001160415.2

2001170012.9

200118003.5

200119002

200120000

200140009.4

2001410018.5

200142008.8

200143004.6

2001440018.3

200145009.6

200146006.4

2001470016.4

2001480014.5

200149007.1

200150007.4

2001510015.1

2001520010.8

200210012.5

200220022.6

200235024.32001/2002

200246025.4

200253011.5

2002611019.8

200275027.9

200287025.8

200298022.8

2002107020.4

2002114012.9

2002127129.1

2002135015.7

200214004.6

200215107.7

200216102.8

200217105

200218004.2

200219002.6

200220006

200240004.2

200241002.5

200242005.7

200243006.4

200244005.5

2002450014.1

200246001.3

2002470014.1

2002480012.5

200249003.5

2002500010.1

2002510014.4

200252005.1

200310015.3

200321115.3

20033108.12002/2003

200344112

200355415.2

20036121123.6

20037111036.1

20038111052.6

200399737

2003107719.9

2003113318.8

2003124117.4

2003135123.8

2003144114.6

2003157211.4

200316008.1

2003173010.1

200318006.4

200319003.7

200320001.4

2003400014.1

2003414031.8

2003429020.7

2003437026.6

20034429158.4

20034536272.7

20034628082.3

20034739162.9

20034832458.3

20034920934

20035014033.1

20035115324.9

2003522016.4

2004110129.4

200425042.7

2004330162003/2004

20044009.1

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20046107.3

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200411005.5

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200415201.2

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200418100

200419002.9

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2004401108.6

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2004420009.9

2004432208.9

20044411010.5

20044544014.4

20044633010.7

2004473309.2

20044855014.7

20044944015.5

20045066018.4

2004511414035.4

2004522424053.8

2004531111049.8

200411920189

200521112131.3

200532324128.52004/2005

2005457215.8

200554629.7

2005622012.3

200571107

2005813214.2

20059710313.7

20051026418.9

20051116516

20051206613.1

20051304411.2

2005140449

2005150111.9

2005160224.9

2005171763.3

2005180223.9

2005190115.8

2005200005

2005210004.2

2005220004.3

2005230003.3

2005240006.2

2005250000

2005260110

2005270002

2005280001

2005290000

2005300001.1

2005310000

2005320000

2005330005.3

2005340000

2005350002.7

2005360005.1

2005370003.7

2005380002.4

2005390000

2005400004

20054100011.5

2005420006.7

2005430005.6

20054400010.5

2005450009.9

2005460008.1

2005470008.3

20054800012.9

20054900011.3

20055000016.8

20055100016.3

2005521108.2

200510009.7

2005222010.8

2005300117.72005/2006

2005438516.3

2005538516.1

20056

20057

20058

20059

200510

200511

200512

200513

200514

200515

200516

200517

200518

200519

200520

lisadomegan:Please note that in order to present flu positive specimens as overlapping bars, flu B specimens need to be added to flu As. Ask Lisa D/Kate H if you need more information.

Why is there concern about avian influenza A/H5N1?H5N1 has causes the largest outbreak in birds on record, since late 2003Despite culling >150 million birds, its become endemic in parts of SE Asia

Why is there concern about avian influenza A/H5N1?May mutate and start the next pandemicDomestic ducks can excrete large quantities of H5N1without signs of illness - silent reservoirs H5N1 viruses now more lethal to experimentally infected mice and to ferrets (a mammalian model)H5N1 has expanded its host range.The behaviour of the virus in its natural reservoir, wild waterfowl, may be changing. Spring 2005 die-off of circa 6,000 migratory birds at a nature reserve in central China, due to H5N1, was highly unusual and probably unprecedented.

Why is there concern about avian influenza A/H5N1?When humans become ill with AI:unusually aggressive clinical course with severe disseminated disease affecting multiple organs and systems Rapid deteriorationHigh fatalityIt causes death in >50% of those affectedMost cases have occurred in previously healthy children and young adults

Controlling Spread?

Guidance re avian influenza at Phase 3Clinical assessment of people with ARI coming from country affected by H5N1Algorithm/guidelines for assessmentTravel advice No travel restrictionsAvoid wet markets, contact with poultryIf ill on return contact GPGeneral public concernsSeasonal flu vaccine for poultry workersIf an outbreak of AI occurred in birds, exposed workers might be under public health surveillance and given oseltamivir prophylactically

Details available at www.hpsc.ie/A-Z/Respiratory/AvianInfluenza/

Lessons from past pandemicsOccur unpredictably, not always in winter Great variations in mortality, severity of illness and pattern of illness or age most severely affectedRapid surge in number of cases over brief period of time, often measured in weeksTend to occur in waves - subsequent waves may be more or less severe Key lesson unpredictabilityWill also depend on the availability and effectiveness of antiviral drugs and vaccines

Emergence of pandemic virus: 3 requirementsNovel virus subtype emerges, with little or no immunity in humansVirus can replicate in humans and cause serious illnessCan be transmitted efficiently from person-to-person

WHO alert phases

Sheet1

Inter-pandemic phase New virus in animals, no human casesLow risk of human cases1

Higher risk of human cases2

Pandemic alert New virus causes human casesNo or very limited human-to-human transmission3

Evidence of increased human-to-human transmission4

Evidence of significant human-to-human transmission5

PandemicEfficient and sustained human-to-human transmission6

Sheet2

Sheet3

Four EU alert levelsAlert level 0No cases anywhere in the world

1Cases only outside the EU

New virus isolated in the EU

Outbreak(s) in the EU

4 Widespread activity across the EU

Expected scale and severity

Epidemic progression in IrelandWeighted sum of deaths over time from previous pandemics (1918, 1957, 1968) based on HPA UK planning model, Oct 2005

Chart2

7.756061945.217714396

10.9877544157.391762061

44.16646382529.711984755

168.0480087113.05047858

568.34698327382.342516018

1160.82393702780.917921268

1139.71021285766.71414319

768.71191672517.133471248

523.10328862351.905848708

406.33146719273.350259746

281.80358382189.576956388

140.25545341594.353668661

84.4548966856.815112312

46.5363716431.306286376

35.3331710623.769587804

Hospitalisations per week

Deaths per week

Week

Number of people

Sheet1

WeekProportion of total casesNo. casesCases per 100,000GP ConsultationsA&E ConsultationsHospitalisations per weekDeaths per week

10.1%1,410361417185

20.2%1,99851200100117

30.8%8,0302058034024430

43.1%30,5547803,0551,528168113

510.6%103,3362,63810,3345,167568382

621.6%211,0595,38821,10610,5531,161781

721.2%207,2205,29020,72210,3611,140767

814.3%139,7663,56813,9776,988769517

99.7%95,1102,4289,5114,755523352

107.5%73,8781,8867,3883,694406273

115.2%51,2371,3085,1242,562282190

122.6%25,5016512,5501,27514094

131.6%15,3553921,5367688457

140.9%8,4612168464234731

150.7%6,4241646423213524

All weeks1979,34025,00097,93448,9675,3863,624

979300.75

WeekProportion of total casesNo. casesCases per 100,000GP ConsultationsA&E ConsultationsHospitalisationsDeaths

10.1%15,000251,5007508356

20.2%30,000503,0001,500165111

30.8%120,00020012,0006,000660444

43.1%465,00077546,50023,2502,5581,721

510.6%1,590,0002,650159,00079,5008,7455,883

621.6%3,240,0005,400324,000162,00017,82011,988

721.2%3,180,0005,300318,000159,00017,49011,766

814.3%2,145,0003,575214,500107,25011,7987,937

99.7%1,455,0002,425145,50072,7508,0035,384

107.5%1,125,0001,875112,50056,2506,1884,163

115.2%780,0001,30078,00039,0004,2902,886

122.6%390,00065039,00019,5002,1451,443

131.6%240,00040024,00012,0001,320888

140.9%135,00022513,5006,750743500

150.7%105,00017510,5005,250578389

All weeks115,015,00025,0001,501,500750,75082,58355,556

15000000

WeekProportion of total casesNo. casesCases per 100,000GP ConsultationsA&E ConsultationsHospitalisationsDeaths

10.14400%21,600362,1601,08011980

20.20400%30,600513,0601,530168113

30.82000%123,00020512,3006,150677455

43.12000%468,00078046,80023,4002,5741,732

510.55200%1,582,8002,638158,28079,1408,7055,856

621.55200%3,232,8005,388323,280161,64017,78011,961

721.16000%3,174,0005,290317,400158,70017,45711,744

814.27200%2,140,8003,568214,080107,04011,7747,921

99.71200%1,456,8002,428145,68072,8408,0125,390

107.54400%1,131,6001,886113,16056,5806,2244,187

115.23200%784,8001,30878,48039,2404,3162,904

122.60400%390,60065139,06019,5302,1481,445

131.56800%235,20039223,52011,7601,294870

140.86400%129,60021612,9606,480713480

150.65600%98,4001649,8404,920541364

All weeks1.0000415,000,00025,0011,500,060750,03082,50355,502

Sheet1

No. cases

Week

Number of cases in Ireland

Sheet2

Hospitalisations per week

Deaths per week

Week

Number of people

Sheet3

Hospitalisations per weekLatent = 2 daysInfectious = 4 days

Effect of antivirals on hospitalisations per week, Ro=1.39Latent = 2 daysInfectious = 4 days

Effect of antivirals on hospitalisations per week, Ro=1.8Latent = 2 daysInfectious = 4 days

Key components of pandemic flu preparedness and response

Surveillance and early diagnosisAntiviral drugsVaccines (once they become available)Public health interventionsHealth system response and government responseCommunications

Public health interventionsPersonal interventionsBasic measures to reduce the spread of infectionHand washing: prevents acquiring the virus from contact with infected surfaces and from passing it onRespiratory hygiene: covering the mouth and nose when coughing or sneezingAvoiding crowds (where feasible): non attendance at large gatherings such as concerts, theatres, cinemas, sports arenas etc. nb STAY AT HOME IF YOU ARE SICK

Possible population-wide interventionsTravel restrictionsRestrictions of mass public gatheringsSchools closureVoluntary home isolation of casesVoluntary quarantine of contacts of known cases

AntiviralsGovernment has ordered stockpile sufficient to treat 25% of the population (including HCWs)Rationale:50% infection rate50% of cases asymptomatic 25% clinical attack rateEnough to treat all who require itPlan is to treat, not to give prophylaxisCould lead to 50-77% reductions in hospitalisations and LRTI requiring hospitalization (Gani 2005)Initial shipment of 600,000 doses delivered. Balance due 2006.Logistics of rapid delivery being examined

Vaccines

Routine seasonal flu vaccines will provide little or no protectionThe new virus strain has to be identified, and new vaccine must be developed to match the pandemic strain of virusFour to six months to produce, possibly longerUnlikely to be available during the early stages When available, aim to immunise whole population as soon as possible 2 dose schedule probableAs production will take time, vaccines will be given to some groups before others according to nationally agreed priorities

VaccinesPandemic vaccine priority groupsProviders of essential services (fire, utilities, etc)HC staff with patient contactHigh medical risk e.g. CHD, RF, DM, pregnant women (3rd trimester), children 6 months- 23 months>65 yrsSelected industries maintenance of essential suppliesAll age groupsH5N1 vaccineNot matched to pandemic strainMay provide some protection pending development of pandemic vaccineEnough to vaccinate 200,000 HCWs and essential staff

SummaryOpportunities for intervention depend on good surveillance dataUnusual clusters are notifiable let us know!Guidance for control in new and emerging diseases evolve on practically a weekly basis check the web site www.hpsc.ie for latest updates

Expansion to responseToo often perceived as traditional surveillance systemsRecent public health threats have proven the importance of expanding sources and ways of monitoring threatsHealth event monitoringNeed for standard operating proceduresNeed for integration of processesAttempt to conceptualize a common framework

In term of risk terminology:- Risk monitoring- Risk assessment, encompassing signal assessment and alert investigation- Risk management, implementation of control measures- Risk communication, dissemination of information

Epidemic intelligence, in its broad sense could be considered as the risk monitoring and assessmentThe components of epidemic intelligence are dual in nature:- the indicator-based component refers to traditional surveillance systems collecting routinely data about diseases of health events in order to detect aberration which may indicate a public health threat requiring intervention- the event-based component which refers to active review of unstructured information originating usually from non health care sources which may indicate a public health threat requiring intervention

While very different in nature, these 2 components follow similar processes for their handling: collect of data versus capture of events, filtering of events vs analysis of data, verification of events vs interpretation of indicators

They both generate unusual health events or signals which need to be assessed for their public health relevance, generating public health alerts which should be investigated, controlled and communicated.

The indicator-based surveillance is operated in most countries, using defined standard operating procedures. However, the event-based component is often operated on an ad-hoc basis and lacks a structured approach because of its diverse nature. Traditionally, te indicator-based EI component relies on system collecting routinely data on occurrence DTaP BCG*95% against tetanus, 50% against all TB97% against diphtheria 64% against meningitis80-84% against pertussisIPV90% protected after 2 doses99% protected after 3 dosesHib95% after 3 dosesMMR90-95% after 1 dose99% after 2 dosesMen C Vaccine (short term efficacy data)97% in adolescents92% in toddlers Pink Book 2002 *Vaccines Plotkin 3rd edition

% Uptake at 24 monthsCohort born 01/04/2001 30/06/2001Health BoardNo. in cohortD3P3T3Hib3Polio3MenC3MMR1ERHA5,34183838383 837974MHB88292899292 929288MWHB1,20786848685 868378NEHB1,51789898989 928678NWHB77893919391 939082SEHB1,63686868686 868582SHB2,05985848585 858479WHB1,26283828383 838071Ireland14,72086858685 868377

Important to know when influenza circulating in the community report is available weekly on the HPSC web siteWeek 6, Peak hosps 1,161, deaths 781. Total hosps 5386, deaths 3624. 0.55% and 0.37%, could be significantly higher in realityWeek by week estimates of pandemic progression Weighted sum of deaths over time from previous pandemics (1918, 1957, 1968)

Overall Clinical Attack Rate assumed 25%0.55% of cases result in hospitalisation0.37% of cases result in death

No other assumptions - duration of infectious/latent periods - value of RoRo determines the Serological Attack Rate (SAR)- Ro=1.39, SAR = 50% - Ro=1.8, SAR = 73%

What proportion of cases are clinical?- Assumed 50% ie clinical attack rate (CAR) half of SAR

sum(hosps128[1,1:100]*3917203)##3,631##max = 320 at 33sum(hosps139[1,1:100]*3917203)##4,533##max = 542 at 25sum(hosps180[1,1:100]*3917203)##6,603##max = 1400 at 15

AVT given to all symptomatic cases in first 2.5 days of infectious periodShortens infectious period by 1.5 daysNo AVT for under 1s

AVT delays peak and much lower. 4,533 hosps over course of untreated scenario, peaking at around 540 in highest week.5% coverage max 316 in 60th week total no is 4,10612% coverage max 93 in 55th week total no is 2,028

Untreated situation, max of 1,400 in 15th week, total hosps 6,60310% AVT, max of 1,026 in 21st week, total hosps 6,29225% AVT, max of 728 in 21st week, total hosps 5,395> =28% AVT same max as in 25% scenario but total lower at 5055 due to lack of AVT at the end in the 25% scenario

How influenza spreadsEasily passed from person to person through coughing and sneezingTransmitted through breathing in droplets containing the virus, produced when infected person talks, coughs or sneezestouching an infected person or surface contaminated with the virus and then touching your own or someone elses face

Seasonal prophylaxis:75 mg once daily for 6 weeks84% reduction in influenza illness in ambulatory adults92% reduction in nursing home residentsPost-exposure prophylaxis in household contacts > 12 yrs: 75 mg once daily for 7 days89% reduction in illness