INFLUENZA AND INFLUENZA VACCINE

PREPARED BY-MANISH KUMAR SINGH[SR.RSM]LUPIN RESPIRA

WHAT IS INFLUENZA? Influenza, commonly known as “the flu”, is a

highly contagious infection of the airways caused by influenza viruses.

It is often referred to as “seasonal” influenza because these viruses circulate annually in the winter season in the northern hemisphere.

The timing and duration of influenza season varies -outbreaks can happen as early as October but most often activity peaks in January or later.

Late season outbreaks occurring in April and even May have also been reported.

WHAT IS INFLUENZA?

Influenza, commonly called "the flu," is an illness caused by RNA viruses of the  family Orthomyxoviridae the influenza viruses that infect the respiratory tract of many animals, birds, and humans.

A, B AND C INFLUENZA VIRUSES

Influenza A and B viruses cause seasonal epidemics, while type C viruses cause mild respiratory illness

Influenza A viruses are classified into different strains or subtypes based on two proteins or antigens on the virus surface: hemagglutinin (H) and neuraminidase (N) e.g., H1N1 and H3N2

Influenza B viruses can be classified into two antigenically distinct lineages, Yamagata and Victoria like viruses

Influenza A and B strains are included in each year's influenza vaccine

The vaccine does not protect against influenza C viruses

SIGNS AND SYMPTOMS OF INFLUENZA

Sudden onset Typically starts with a headache, chills and cough,

followed rapidly by fever, loss of appetite, muscle aches and fatigue, runny nose, sneezing, watery eyes and throat irritation

Nausea, vomiting and diarrhea may also occur, especially in children

SIGNS AND SYMPTOMS

Fever (usually 100 F-103 F in adults and often even higher in children)

Cough, Sore throat, Runny or stuffy nose, Headache, Muscle aches, Extreme fatigue

HOW IS INFLUENZA SPREAD?

The virus is spread mainly from person to person when those with influenza cough or sneeze (droplet spread)

The droplets are propelled about 3 feet through the air

People may also become infected by touching an object or a surface that has the influenza virus on it and then touching their mouth, eyes or nose

INFLUENZA VACCINE DEVELOPMENT

Each February, the World Health Organization (WHO) provides a recommendation on the strains to be included in the influenza vaccine for the northern hemisphere

Two influenza "A" viruses and one influenza "B" virus are selected based on the characteristics of the current circulating influenza virus strains (two "B" viruses are selected for quadrivalent vaccines)

A new vaccine is reformulated each year to protect against new influenza infections

Each vaccine lot is tested on healthy individuals to ensure the vaccine is safe and effective

INFLUENZA VACCINE DEVELOPMENT (CONT’D) There are currently eight trivalent influenza

vaccines licensed for use in Canada Seven are trivalent inactivated influenza vaccine

(TIV) One is a live attenuated influenza vaccine (LAIV) There are currently three quadrivalent influenza

vaccines licensed for use in Canada Two are quadrivalent inactivated influenza vaccine

(QIV) One is a live attenuated influenza vaccine (QLAIV) For the 2014–2015 influenza immunization

program, Alberta will be using three TIV products and one QLAIV product

HOW DOES INACTIVATED INFLUENZA VACCINE WORK?

Both humoral and cell-mediated responses play a role in immunity

Administration of inactivated influenza vaccine results in the production of circulating IgG antibodies to the viral haemagglutinin as well as a cytotoxic T lymphocyte response

Humoral antibody levels, which correlate with vaccine protection, are generally achieved 2 weeks after immunization and immunity usually lasts less than 1 year

Initial antibody response may be lower in the elderly and immune.

HOW DOES LIVE ATTENUATED INFLUENZA VACCINE WORK?

Immune mechanisms conferring immunity following administration of live attenuated vaccine are not fully understood

Administered by the intranasal route, QLAIV is thought to result in an immune response that mimics that induced by natural infection with wild-type virus, developing both mucosal and systemic immunity

Serum antibodies, mucosal antibodies and influenza-specific T cells may play a role

The viral strains in QLAIV are engineered to be cold adapted (can only replicate in the nasopharynx), temperature sensitive (cannot replicate in the warm temperatures of the lower airways and lungs) and attenuated (unable to cause clinical disease)

EFFECTIVENESS OF INFLUENZA VACCINE Vaccine effectiveness depends on the similarity between

vaccine strains and the strains in circulation during influenza season

With a good "match," influenza immunization prevents disease in 70 to 90% of healthy individuals

This drops to 30 to 40% in the frail and elderly It does, however, prevent death in 85% of the frail and elderly It prevents hospitalization in 50 to 60% of individuals

immunized Even with an imperfect match, Canadian studies show the

vaccine still reduces the overall risk of infection by about 40-60%

A vaccine that is not perfectly matched can still offer protection against related viruses making illness milder and preventing complications

QLAIV has generally shown to be equally or more immunogenic than TIV in children and adolescents 2 to 17 years of age

VACCINE STRAINS FOR 2014-2015 The strains that will be included in the 2014-2015

influenza vaccine for the Northern hemisphere are:

A/California/7/2009 (H1N1)pdm09-like virus A/Texas/50/2012 (H3N2)-like virus B/Massachusetts/2/2012-like virus B/Brisbane/60/2008-like virus (B/Victoria lineage)

(Quadrivalent QLAIV only)

FACTS ABOUT TRIVALENT INACTIVATED INFLUENZA VACCINE (TIV)

Is an inactivated (killed) vaccine –cannot cause influenza disease in the vaccine recipient

The virus is grown in hens’ eggs, inactivated, broken apart and highly purified

In addition to the antigen, the vaccine may contain:

Thimerosal (preservative in multidose vials) Trace residual amounts of egg proteins,

formaldehyde, kanamycin, neomycin, cetyl trimethyl ammonium bromide (CTAB), polysorbate 80, sodium deoxycholate and sucrose

Check the product monograph as ingredients vary with specific inactivated influenza vaccines

FACTS ABOUT LIVE ATTENUATED INFLUENZA VACCINE (QLAIV)

Is a live vaccine –cannot cause influenza disease in the vaccine recipient because the virus is attenuated or weakened (however is contraindicated in immuno compromised individuals)

The virus is grown in specific pathogen-free eggs from specific pathogen-free chicken flocks

In addition to the antigen, the vaccine may contain:

Trace residual amount of arginine, gelatin hydrolysate (porcine type A), gentamicin, monosodium glutamate, ovalbumin and sucrose

Check the product monograph for other product excipients

INFLUENZA VACCINE DOSING FOR SPECIFIC AGES

6 months up to & including 8 years of age 2 doses * if never been previously immunized with seasonal

influenza vaccine (spaced 4 weeks apart –minimum interval)

1 dose only if previously immunized with seasonal influenza vaccine

9 years of age and older

1 dose

*This recommendation applies whether or not the child received monovalent pH1N1 vaccine in 2009-2010.

REACTIONS TO INACTIVATED INFLUENZA VACCINE The majority of people do not have a reaction to

TIV; however some reactions that may occur are outlined below. These reactions generally start 6 to 12 hours after immunization and can last for 1 to 2 days

Common Reactions Injection site redness, swelling, pain Fatigue, headache, myalgia Arthralgia, fever, chills, malaise

REACTIONS TO LIVE ATTENUATED INFLUENZA VACCINE

Most people have no reaction to QLAIV. If reactions occur they tend to be mild and last for 1-3 days, peaking 2 days following immunization.

Common Reactions Runny, stuffy nose in children and adults Children –decreased appetite, headache, weakness

and fever Adults –sore throat, headache, cough and weakness

For children requiring two doses of vaccine, the symptoms tend to be less frequent following the second dose.

THANKS & REGARDS !!