dr.vineet jain

8/9/2019 Dr.Vineet Jain

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Influenza (flu) Vaccine

Dr Vineet jainMD (Ped) AIIMS

Sr Consultant, PediatricsPushpanjali Crosslay Hospital


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Influenza

Highly infectious,RNA virus

Antigenetically 3 types:

A mod to severe ilness,all age gps,human + other animals

B milder illness,primarily in children, only humans

C mostly sub clinical ,not @ with Epidemics

Spread : droplet inhalation / direct contact with resp. secretions

Incubation period : 1-4 d

Period of infectivity: 5-10 d Season :

northern hemisphere Winter (Nov feb )

Southern hemisphere summer ( jun Aug )

Tropics-round the year??


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Influenza cont..Symptoms-

very abrupt onset Fever, chills,headache,

myalgia and extreme fatigue.

Dry cough,sore throat and stuffy nose.

Complications-bacterial pneumonia, bronchitis, otitis media,

meningitis, encephalitis ormeningoencephalitis.

Risk highest among very young, very old, chronicrespiratory and cardiac disease, immunosuppressed,pregnancy

30 to 50% of influenza infections are asymptomatic.


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Changing VirusInfluenza virus A : notorious for mutation

Virus is constantly changing -

DRIFT : minor changes in Ag epidemic

SHIFT : major change in Ag Pandemic

New virus is born

Existing vaccines become ineffective

Epidemics & Pandemics


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Influenza VaccineFirst vaccine in USA in 1945

2 types of Influenza vaccines :

Inactivated (killed) virus vaccine Available in INDIA

whole-virus ( obsolete )

split virion (surface proteins+ matrix proteins )

Sub unit (only surface proteins )

Live attenuated Intranasal Vaccine

All developed in hen egg embryo

Trivalent containing

two subtypes of influenza A ( H1N1subtype , H3N2 subtype ) and

one type B virus-15Qg each

Efficacy 70-90% for matched strains


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Who should receive vaccine?CDC guidelines

*All children & adolescents 6mo-18y (esp if on long term aspirin)

High risk people

> 50y (protection rate 40-50% at 65y & 15-30% at 70%)

chronic pulmonary ,cardiac & renal disorders /DM

immunocompromised (HIV/Steroids/chemoRx/radiation Rx)

Health personnels

household contacts of Flu case

*Pregnancy

*likely to b pregnant in Flu season

* IAPCOI do not recommend due to lack of Indian data & other health

priorities


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Contraindications

Inactivated split virusvaccine


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Influenza Vaccine Dose*

9yrs 1 dose

then yrly 1 dose im/sc

3yrs 0.5 ml

*package inserts should be consulted


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How safe is the flu vaccine?

Very safe

Minor sideffects - local soreness/redness/swelling 15-20%

Serious adverse reactions RARE

as a result of allergy to egg proteins

Gullian Barre Syndrome

Flu vaccine is recommended by CDC/AAP/AAFP/IAPCOI


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Efficacy of flu

vaccine

Depends upon

Similarity of vaccine strain to circulating strain

Age< 65y better protection 75-90% for matching strains

> 65y lesser protection

(but dec. mortality & CCx 30-70%

Immunological status

immunocompromised are less protected

Seasonal flu vaccine will not protect against new 2009H1N1 swine flu


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Vaccine limitations

New vaccine every year

Manufacturing is complex,tight

schedule,limited Timed to suit temperate climates

Few manufacturers

Availability in crisis ???

Lack of Indian data on disease burden Cost

Health priorities in India are different


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Flu vaccine: special situations

Pregnancy

killed flu vaccine doesnt harm fetus &

pregnant women are at high risk for serious

medical CCx, so strongly recommended.

In addition vaccination of mother will

provide some protection to her newborn.


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Fluv

accine: special situationsBreastfeeding mother

mothers should be immunised as they are

close contacts for the babies upto 6 mo

who cannot be directlyvaccinated


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Misconceptions about flu vaccineclarified

Q: Can flu vaccine cause influenza? NO

Killed vaccine

Q: Can people get sick with flu like symptoms despite vaccination?

YES Other strains not covered by vaccine

Other viruses like rhinovirus

Already in incubation period


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Common coldv

sF

lu Severity + +++

Fever + +++ very abrupt onset

Bodyaches +/- ++ Tiredness +/- +++

Dry cough + ++

Coryza +++ +

CCx ie Pneumonia rare common

Hospitalization - ++


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Misconceptions about flu vaccineclarified cont.

Does getting vaccinated against seasonal flu

early in the season pose a risk that immunity

may wane before end of season ?

No

Protection lasts for 1 yr

flu in tropical countries circulate throughout the

year. There is no season


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Misconceptions about flu vaccineclarified cont.

Is pregnancy a contraindication for fluvaccine?

NO

killed flu vaccine doesnt harm fetus &pregnant women r at high risk for serious

medical CCx ,so strongly recommended. in addition vaccination of mother will

provide some protection to her newborn


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misconceptions about flu vaccclarified cont.

Child < 9 y who received only 1 shot of flu inprevious season can be protected by 1 dose in

current season ?No

children


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Air born Air born

Mixing reservoir


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Thank You

dr.vineet jain

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