Mitigation strategies for the protection of health care

workers and first responders

Dr John WatkinsDepartment of Primary Care and Public Health

School of MedicineCardiff University

Consultant National Public Heath Service for WalesUK

Cases of laboratory confirmed swine-lineage influenza A H1N1 by day of report and travel history, United Kingdom, 06 May 2009 (n=32)

15

10No relevant travel historyTravel to MexicoTravel to New YorkTravel to Texas

5

16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 1 2 3 4 5 6April May

Date of report

Properties of the Virus

• Swine Origin Influenza A H1N1 S-OIV

• HA and NA genes worldwide cases great homogeneity 99%

• Greater than 90% similar to HA and NA swine virus genes that have been circulating for past 20 years

• Less than 90% similarity with H1N1 Human seasonal virus

• Canada great experience with SARS in dealing with a highly contagious disease

• World leading policy on vaccination – Ontario introduction of universal vaccination against influenza –Susan Tamlyn

Pandemic vaccines

Vaccine supply

• Internationally 400 million doses – 1.2 Billion of monovalent vaccine

• UK 20 million doses• World population 6-7 billion• Production capacity with adjuvants and single

component 3.6 billion doses• Production plus licence takes 6 months• Naive population needs two doses 12-14 billion

doses

Vaccine Options

• Replace seasonal programme• Produce a single valent vaccine• Issue quadruple vaccine• Replace H1N1 antigens in seasonal

vaccine with Swine strains (need two doses)

• New technologies using substrates other than eggs UK DH has contract with Baxter for cell culture vaccine

Who is at risk?

Age specific attack rate confirmed cases reported by México

 Age (years) N°

Population from US census office rate per 100,000

< 5 102 10,772,705 0.95

5 to 14 208 21,783,444 0.95

15 to 29 279 29,722,159 0.94

30 to 44 134 23,687,456 0.57

45 to 59 77 14,349,342 0.54

60 + 19 9,640,294 0.20

No details 3  

Total 822 109,955,400 0.75

Fig. 5. Deaths from Pneumonia and Influenza in USA in Two Influenza Pandemics*

0

500

1000

1500

2000

0 10 20 30 40 50 60 70 80 90

Age

De

ath

s p

er

10

0,0

00

po

pu

lati

on

1892**

1918

*Adapted from Dauer & Serfling (43)**Massachusetts only

Age as a risk factor for Pandemic Influenza

00.5

11.5

22.5

33.5

44.5

Age Band

Rel

ativ

e ri

sk c

om

par

ed t

o a

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Jan-April 1966

Dec 67-Mar68

Jan-april 69

Dec69-Feb 70

dec 71-Feb72

Dec 72-Feb 73

Jan-apr 74

Jan-apr 75

Jan-apr 76

Vaccine issues

• Strategy vaccinate high risk and young• Adjuvanted vaccine how safe are they FluAd

from Novartis 50 million doses no increased events e.g. GBS, GSK clinical trials with adjuvanted H5N1 vaccine.

• International agreements about sharing vaccine• Who speaks for Africa and other poor countries• S-OIV antigen distributed to vaccine

manufacturers this week

Influenza

• Strongly seasonal

• Previous pandemics demonstrate a ‘Herald Wave’ phenomena

• Next few months in southern hemisphere crucial

Influenza Public Health Strategies

• Containment phase

• Epidemic/Pandemic phase

• Role of containment strategies e.g. social distancing, personal protective equipment (PPE), closure of schools and other public gatherings, masks.

Containment phase

• Case identification• Epidemiological features

Attack rateVulnerable groupsVirulenceTransmissibilityCase fatality rate

• Contact tracing and management• Case Management

Case Management

• Isolation

• Personal protective equipment for HCW –correctly fitted high filtrate mask FFP3, long sleeve gown, gloves, eye protection

• Antiviral therapy for lab test +ve cases and contacts and health care workers HCW who have provided direct care to case and not wearing PPE at the time

From Rashid A. Chotani Just-in-Time Lecture

1918-MOST FATAL 1918-MOST FATAL EVENTEVENT

IN HUMAN HISTORYIN HUMAN HISTORY

WORLDWIDE FATALITIES:50-100 MILLION

US FATALITIES:675,000

U.S. LIFE EXPECTANCY AT BIRTH

35

40

45

50

55

60

65

70

1900 1906 1912 1918 1924 1930 1936 1942 1948 1954 1960

Date

Ag

e

Antivirals- Tamiflu

Kaiser et al, 2003Reduction in complications

0

5

10

15

All Bronchitis Pneumonia

Patients(%)

Patients(%)

55%52%

61%

**, p<0.001 vs placebo

Placebo (n=1063)Tamiflu® (oseltamivir) (n=1350)

10.3

8.2

1.84.6** 3.90.7

n=109 n=87 n=19n=62 n=53 n=9

Kaiser et al. Arch Intern Med 2003; 163: 1667-72.Kaiser et al. Arch Intern Med 2003; 163: 1667-72.

Kaiser et al, 2003Reduction in

hospitalisations

0

1

2

3

4

Overall Healthy At risk

59%

62%

50%

1.7

0.7* 0.8 0.3

3.2

1.6

n=18 n=9 n=5 n=3 n=13 n=6

Placebo (n=1063)

Tamiflu (n=1350)Placebo (n=662)

Tamiflu (n=982)Placebo (n=401)

Tamiflu (n=369)

P=0.17

P=0.02

Patients(%)

Patients(%)

PlaceboTamiflu® (oseltamivir)

Kaiser et al. Arch Intern Med 2003; 163: 1667-72.Kaiser et al. Arch Intern Med 2003; 163: 1667-72.

Earlier Treatment With Oseltamivir Maximises Clinical Benefits

-4

-3

-2

-1

0

Reduction of Illness Duration ((Days) Compared With Intervention at 48 h

Reduction of Illness Duration ((Days) Compared With Intervention at 48 h

Time From Symptom Onset to Treatment (h)

Modeled time to treatment P < 0.0001.Modeled time to treatment P < 0.0001.

–3.1 d –1.2 d–2.2 d

12 24 36

–3.8 d

0

Epidemic/Pandemic Phase

• Containment strategy futile• Move to treatment of symptomatic individuals

with antiviral drugs.• Cessation of contact tracing• PPE for HCW in aerosol generating procedures• Antiviral drugs reserved for all symptomatic

cases including HCW• In UK – National Flu line and population based

primary healthcare delivery

Antiviral stockpile

• Purchased 15 million treatment doses (25% of pop) pre 2008/9 season

• Increased to 33 million doses (50% pop) in 2009

• Now increased to cover 80% of population by next winter

• Stockpile of antibiotics to cover 30% of population by next winter

• Stockpile of masks gowns and other PPE

Protection of HCW in a Pandemic

• Medical/surgical masks• Hand hygiene• In case of splashes gown, gloves and face

protection/eye protection• Aerosol generating procedures full PPE• No seasonal prophylaxis• Antivirals policy same as general population

reserved for HCW who develop symptoms who will also be advised to stay at home.

• Rapid access to antiviral therapy

Contentious issues

• Evidence base for the use of masksMacIntyre R et. Al. EID www.cdc.gov/EID 2009;15:233-241

• Social distancing, school closure, bans placed on mass gathering

• Post exposure prophylaxis and the immune response- still develop immunityLina B et.al. poster V4140 48th annual ICAAC Washington DC Oct 2008

INDOOR CHURCH SERVICES WERE BANNED BY HEALTH DEPARTMENTS

Poem from a lady afflicted

Cannot speak-got no voice Cannot walk-got no legs Cannot sleep-got too much headCannot lie down-cough too muchCannot sit up-sneeze too muchCannot eat-got too big a throatCannot write-got nothing to say.Why?INFLUENZA

Lancet January 11th 1890 p72