First AD

Second AD

The mother of a needle-phobic and mildly egg-allergic 8-year-old convinces your partner to give her child the intradermal flu vaccine Fluzone ID. The mother calls you that afternoon after reading that the intradermal vaccine is only approved for persons aged 18 through 64.

A. Not to worry since the dose “counts” even though it was given off-label

B. The dose does not count and she should bring the child back for a dose of FluMist

C. The dose does not count and she should bring the child back for a dose of “regular” flu vaccine that is given intramuscularly

D. The dose does not count and she should bring the child back for a dose of Flublok, the only completely egg-free flu vaccine

Answer: C-The dose does not count and the child needs to return for a dose of regular vaccine administered intramuscularly. 

The first issue is the inadvertent administration of the intradermal vaccine Fluzone ID. The dermal layer is loaded with dendritic cells which play an important role in eventual antibody production. Consequently, a smaller amount of antigen is in the intradermal vaccine as compared to the IM vaccine to produce the same antibody levels.

The needle is 90% shorter than the typical needle and is ultra fine, making it appealing to the needle-phobic patient. The needle length was designed to deliver antigen in the dermis and not subcutaneously (SQ) where a less robust antibody production would likely result. Since children and older adults have a thinner skin layer, even this shorter needle may enter the SQ space and result in a suboptimal antibody response. Some experts feel that children over age 9 have a thick enough dermal layer for a needle to deliver an intradermal dose. Since the child in our scenario is only 8, she clearly needs a repeat flu vaccine, but which one?

This brings us to the second issue: dealing with the egg allergic patient. The Advisory Committee on Immunization Practices (ACIP) has published some guidelines for administering inactivated, IM flu vaccines to persons with a history of egg allergy and most (but not all) egg-allergic persons will be able to receive the vaccine in their doctor’s office with certain precautions. This recommendation does not extend to the live, intranasal Flumist; only the inactivated flu vaccine should be given to the appropriately chosen egg-allergic patient in the proper setting. Do not have an egg-allergic person receive vaccination in a pharmacy.

Flublok is the only totally egg protein–free influenza vaccine and is new this year in a trivalent formulation only. This vaccine is made through recombinant DNA technology in an insect cell line. (I don’t think I would tell patients this unless asked. It could lead to resistance and we already have enough problems getting everyone vaccinated against the flu without aggravating antivaccine activists.)

Anyone with a severe egg allergy (ie, a life-threatening anaphylactic reaction) should get this vaccine if they meet the age restrictions of 18 to 49 years of age. Studies are under way this 2013-2014 flu season for children aged 6 to 18 years that hopefully will lead to approval of Flublok for this age group next year. Clinical trials for older adults are also planned.

Fluvax is another new vaccine choice introduced this year. It is made in a cell culture of canine kidney cells rather than eggs, but since the seed virus did come from propagation in eggs, a minuscule amount of egg protein is in the vaccine.

In a similar scenario, you might also decide to share the 2 references that follow with the partner while you commiserate on how confusing vaccine administration has become.

. November, 2013. Accessed on January 9, 2014 and available at 

http://www.immunize.org/nslt.d/n58/n58.pdf

- CDC. Prevention and control of seasonal influenza with vaccines: recommendations of the Advisory Committee on Immunization Practices-United States, 2013–2014. 

 2013;62(RR07):1-43. Full text available at 

http://www.cdc.gov/mmwr/preview/mmwrhtml/rr6207a1.htm

Flu Season Scenario #2