Flu shot: Answers

It is the month of October in your busy practice and you are about to call your next patient, Runny Knowse, an 8 month old girl here for a walk in visit.  The nurse’s triage notes that Runny is here for nasal congestion and a cough.  As you are about to enter the patient’s room, your head nurse tells you “We’ve got the flu shot”. 

1)Does Runny need one?  Can you give her one, if so which vaccine would you recommend?

The latest recommendations in 2008 from the CDC and the American Academy of Pediatrics recommend influenza vaccination for 6mos-18 years, with primary focus on 6 mos to 59 mos. Based on this, it is recommended that Runny receive her vaccine today.  These recommendations continue to evolve as to more effectively protect against the morbidity and mortality of influenza.  In recent years the age range has been expanded to include more children in order to protect them directly and also to promote protection to other individuals through herd immunity. 

Additional recommendations include: all children with chronic pulmonary disorders (asthma, CF), cardiovascular disorders, chronic metabolic disorders (diabetes), renal disease, hemoglobinopathies, children on long-term aspiring therapy (to prevent Reye’s Syndrome) or immunosuppressed children.  Also, all household contacts and out-of-home caregivers of children with high-risk conditions and of healthy children younger than 5 years of age and all health professionals should receive influenza vaccination. 

Influenza is caused by Influenza A or B virus and generally occurs in outbreaks and epidemics annually usually during the winter months.  Annually, the CDC and the WHO track influenza activity worldwide to predict the most effective components for the vaccine which will offer protection for the upcoming influenza season. This process takes months and has often led to delays in production and delays in dispensing the vaccine product to reach the population effectively.  The ultimate vaccine produced includes components of Influenza A and B.  Changes in the influenza virus both minor (antigenic drift) and major(antigenic shift) directly result in the need to manufacture a new vaccine product annually and pose challenges to the immunization process. It is recommended that vaccination against influenza begin in the fall as influenza tends to peak in January or February and that vaccination continue until March as influenza season extends through then.

Given Runny’s age, 8 months, she is able to receive the trivalent inactive vaccine (TIV) (brand name - Fluzone)  which is approved for all ages above 6 months.  It is an intramuscular vaccine prepared from inactivated preparations of either whole virus or subvirion components, also known as “split product”.  Only split product vaccines are available in the United States. Given that it is an inactive vaccine, with killed virus particles, TIV does not produce an active influenza illness.  However, given the immune response that the body’s immune system develops to the vaccine, patients may hypothetically experience an influenza-like illness.  All children under the age of 2 should receive the TIV as it is the only product approved in the US for this age group. 

The only true contraindications to TIV include:

-children less than 6 months

-children with moderate to severe febrile illness (minor illnesses with or without fever do not contraindicate the use of TIV)

-children with allergy to eggs or any vaccine components

-children with h/o of Guillan Barre Syndrome

Therefore, if on your exam Runny appears well, without evidence of high fever or toxicity she should receive her vaccine today. 

2)How would you write the order for her vaccine and when would you like her to return to your office?

For all children less than the age of 3, the dose of TIV is 0.25 cc IM.  For children 3 and above, the dose of TIV is 0.5cc IM.  If children are less than 9 years of age, they should receive 2 doses, separated by a minimum of 4 weeks, of influenza vaccine the first season that they receive the vaccine.  In subsequent years they can receive one single dose.

For children who received only 1 dose for the first time in the previous season, it is recommended that 2 doses be administered in the current season. This only applies to the influenza season that follows the first year that a child younger than 9 years receives the influenza vaccine.

Runny’s order should be: Influenza vaccine 0.25 cc IM, return to clinic in 4 weeks for Influenza vaccine 2nd dose.  Her mother, should be counseled on the importance that all household members and caretakers for Runny receive the influenza vaccine.

3)As you are about to exit the room, mom says “I have one other question before she gets the vaccine, does it contain thimerasol?”

The current vaccine supply in the US does included certain influenza vaccine products with small amounts of the mercury-containing preservative, thimerasol.  Multi-dose vials of TIV have about 25 mcg of thimerasol mercury per each 0.5ml dose. Fluvirin (children ages >4) and Fluarix (individuals >18yr) may contain trace amounts of thimerasol.  However, single dose Fluzone (children ages >6mos) and Afluria (individuals ages >18) are thimerasol free. 

In this case, your office carries Fluzone (TIV approved for children ages 6mos and up) and you can safely reassure mom that it does not contain thimerasol.  The AAP and CDC recommendations make it clear that the benefits of influenza vaccination far outweigh the theoretical risks associated with trace amount of thimerasol.

Case 2

You are about to see Asma Pashent, a 6 year old girl with intermittent asthma who is here for a flu shot.  After reviewing her asthma control and her medications with her and her father, you tell them that she will receive her influenza vaccine today.  Mr. Pashent asks you that he saw an ad for the flu spray vaccine and that he’d prefer Asma get this since she hates shots. 

1)How do you respond?

The second type of influenza vaccine product licensed in the US is the trivalent live-attenuated cold-adapted influenza vaccine (LAIV)(brand name-Flumist).  In 2007, it received licensure for administration in healthy individuals age 2 and above.  It is a live attenuated vaccine prepared through genetic reassortment and administered intranasally.  It is administered by spraying 0.1ml into each nostril separately.  It does not contain thimerasol, but does contain traces of egg. 

LAIV is approved for healthy non pregnant individuals ages 2-49.  Children who are 2 years to 59 months of age and are not in a risk group requiring TIV should receive LAIV.  Household contacts/caregivers of children ages 0-59 months and those at high risk for severe complications of influenza should also receive LAIV.

There are various contraindications to LAIV: less than 2 years of age, h/o allergy to egg, chicken protein, gentamicin, gelatin or aginine, long term ASA therapy, immunodeficiency, h/o Guillan Barre syndrome, asthma, recurrent wheezing in children ages 5 or less.  Finally, due to the active nature of LAIV, contacts of severely immunocompromised (stem cell recipients) should not receive LAIV.  Contact of less immunosuppressed individuals (HIV, diabetes, on steroids) can receive either LAIV or TIV.

Children with minor illnesses, with or without fever can receive LAIV.  If there is nasal congestion, which on exam may appear as severe, LAIV should not be given since the congestion may affect the proper inhalation of the spray.

As with TIV, for all children ages 9 or less they should receive 2 doses of the vaccine in their first year receiving it separated by 4 weeks time.  Again, for children who received only 1 dose for the first time in the previous season, it is recommended that 2 doses be administered in the current season. This only applies to the influenza season that follows the first year that a child younger than 9 years receives the influenza vaccine.

In this case, Asma, cannot receive LAIV due to her asthma diagnosis.  Some studies have shown that there is an existing association between LAIV and asthma both for increases in medically significant wheezing after receiving LAIV, and for increased hospitalization in infants.  Other studies do not show any association between LAIV and poor asthma outcomes.  However, for now LAIV is contraindicated in children with asthma and children with a history of wheezing until further studies are perfomed.

2)Mr Pashent agrees that Asma can receive the TIV but he wants to know if the spray and the shot are the same or if one is better than the other?

Preliminary and limited data shows that LAIV offers greater protection than TIV for young children.  In one study, LAIV recipients during the 2004-2005 season, ages 6 months to 59 months of age, showed a 55% reduction in cases of culture-confirmed influenza when compared to those children receiving TIV.  Data is preliminary, however, overall both vaccine products have been shown to be both clinically and cost-effective, as strategies to prevent influenza disease when there is a close match between the product and a particular season’s strain.