Transcript Influenza presentation by Professor Robert Booy from NCIRS

Influenza
Professor Robert Booy
NCIRS, University of Sydney
February 25th , 2016
The double truth about influenza:
mild and severe disease
• Most cases cannot be distinguished from a common cold
• About 25% have the classic flu presentation..
• Influenza is, by far and away, the most common cause of vaccine
preventable disease AND DEATH in Australia
• The annual number of deaths is 2000-3000
• But the number of those deaths that are proven by laboratory
diagnosis is 5% or fewer – can you think of a personal example?
• Almost all the deaths are in older people but there are about
5-15 deaths in children annually – more than any other VPD
– how many die each year from other causes?
• Children are over-represented in terms of GP visits & hospitalisations
– which age groups of children are especially at risk?
• From what age do we vaccinate? Do we adjust the dose?
A recent example: intelligent,
informed and motivated parents
• Identical twin girls aged 6 years returning from family
holiday in the UK during January; PMH of severe flu
• One developed cold symptoms en route in Singapore –
within two days the other twin and the father both
developed high fever, lethargy, sore throat and cough
• GP did a diagnostic test – what ?
• What treatment was given ?
• Were they immunised?
• How effective is immunisation? Flu A? B? age-based?
• Is there cross-immunity between A strains or B strains?
Past medical history
• Both girls actually had proven & severe influenza A,
two winters ago in Australia
• One was so severe she developed life-threatening
pneumonia: required intensive care admission and
respiratory ventilation
• Her parents worried she might die
• She thankfully improved and was discharged after
two weeks in hospital – another 18 months before
her general health & development matched that of
her identical twin – I followed them in my OPD
• BOTH TIMES, the 2nd twin was more severe…
Two brothers with influenza
• Aged 1 and 4 – the older one got ill first
• Then the infant, who developed encephalitis
• They were of Chinese/Vietnamese background –
why relevant?
• Flu causes a number of life-threatening infectious
complications – brain, lung, heart, sepsis, other?
• Such cases are seldom predictable – both these
boys & the twin girls had no prior or chronic illness
- underlines the importance of PREVENTION
A 73 year old man with emphysema
• Retired early (62) after long smoking history
• Frequent acute respiratory infections, esp’ly in winter
• Mid-July developed fever, cough, SOB, runny nose and
then pneumonia – managed by GP
• Wrote a letter to his son
• 3 days later, had a myocardial infarction and died
• No tests, no treatment, no formal diagnosis
• No immunisation for him or his wife
• Carers can become killers: households, aged care facilities
Herd Immunity: How important is
it for the control of influenza?
The importance of implementing vaccination programs
•Who are the at-risk groups for whom the national
immunisation program provides free protection?
•So many of those for whom we recommend influenza
immunisation may not respond as well as a healthy person –
What can be achieved next month while waiting for
Quadrivalent flu vaccine?
•The very young and the very old are especially at risk and yet
these are the very populations in which we fail to
vaccinate/cannot vaccinate/won’t vaccinate … why?
Herd Immunity
• A safety net to protect those who missed out on direct
immunisation, or whose immune systems weren't able to
mount sufficient defence against the disease-causing virus
• Immunisations are for the whole family and protect the whole
family, they are for institutions where people live, they are for
workplaces, especially hospitals
• You couldn’t go on a construction site without a hard-hat or
drive a car without a seat belt
• Indeed influenza vaccination is recommended for ANYONE
who wishes to protect themselves against this disease!
Herd immunity
• The public can be blasé about vaccine preventable
diseases, because the very success of vaccination
programs means they rarely encounter them anymore
– eg polio 50 yrs ago; what recent outbreaks?
• The importance of determining cost effectiveness and
the role of the PBAC –
• recent recommendation for flu vaccine in indigenous
children aged < 5 years
• What about 50-64 year olds?
Diagnosing influenza
• How easy is it to diagnose influenza?
• How does it compare to the common cold?
• Is there a test that GPs can do in their surgery or that
can be sent to a laboratory?
• How often are cases of influenza formally diagnosed ?
And what percentage of positive cases get specific
antiviral treatment – in primary care? In hospitals?
• What is the impact of early diagnosis and treatment on
disease?
• Disease prevention is the key …..