When performing a vaccine desensitization using a gradually-escalating dose in a child who is allergic to a component of that vaccine (gelatin allergy in the case of my patient), if the patient has an allergic reaction during this procedure, do I treat and "push through" by continuing to give her injections until I finish the four-dose desensitization, or do I stop and say, "That's it, you just had hives, or hives and vomiting and wheezing, etc, and we're not giving you the last one, two, or three doses of this vaccine".

In my patient's case, she is a 4 yo child with very occasional mild intermittent asthma, garlic allergy (proven by me by oral challenge), sesame allergy (proven by me by oral challenge), and gelatin allergy (anaphylaxis to Fluzone vaccine that improved after one dose of epinephrine and an alb. neb treatment in pediatrician's office, with h/o hives on face after eating marshmallow and positive in-vitro IgE to gelatin). She needs her last dose of MMR vaccine and last dose of VZV vaccine. This will be given as "ProQuad" in one injection, which is a combination of MMR + VZV. I just skin-pricked her today to undiluted ProQuad, and she had a large positive skin prick test with wheal-and-flare of 12 X 10 mm wheal, 18 mm flare, with saline control of 3 mm wheal. Therefore, I want to give her the ProQuad vaccine in my office using the protocol that has been used in the past for influenza vaccine desensitization-- give 0.05 mL, 0.10 mL, 0.15 mL, 0.20 mL for total volume of 0.50 mL injected (which is the standard injection volume). I am wondering what to do if she has an allergic reaction after the 0.05 ml, 0.15 mL, or 0.20 mL doses.

I am going to "pre-treat" with cetirizine and montelukast the day before and the morning of the MMR/VZV vaccine desensitization.


Thank you for your inquiry.

Unfortunately there is no definitive answer to your question. You would probably obtain different responses from different experts. A great deal depends upon your confidence in treating an event that might occur if you “push through,” the severity and nature of her reaction, how great the need is for the vaccine you are pursuing, and whether you feel you could give the dose prior to her reaction on another day or a few days (thus giving her the cumulative dose that she needs over several days).

In most instances, in cases where I have encountered a reaction, I will not “push through” on the same day. I will bring the patient back the next day and give the dose that was safely given prior to the reaction, and continue to do this until the cumulative dose reaches the desirable dose. For example, if you were doing so with tetanus toxoid, and the reaction occurred at 0.2 cc, I would bring the patient back in three subsequent days and give the patient 0.1 cc on each occasion. Thus a total of 0.5 cc could be given without further risk However if the reaction was mild you could attempt to "push through" if the patient/parent were willing. There is no consensus and the decision to do so is a "judgment call".

Parenthetically, I see no problem with your suggested protocol for desensitization, but you might want to use a published protocol. For your convenience the two references below contain such a protocol. Although they were done with the presumption that the allergy was to egg protein within the vaccine, the principles employed and schedule would apply to gelatin.

Finally my preference would be to desensitize to MMR alone. I would use separate injections.

Pediatrics Vol. 91 No. 4 April 1, 1993

Ann Allergy. 1994 Jan;72(1):25-8.
Measles, mumps, rubella vaccine administration in egg-sensitive children: systemic reactions during vaccine desensitization.
Trotter AC, Stone BD, Laszlo DJ, Georgitis JW.
Department of Pediatrics, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, NC.
In egg-sensitive children, measles-mumps-rubella (MMR) vaccination may cause acute allergic reactions; therefore, current recommendations are to perform skin testing with the commercial vaccine before administration to egg-allergic children. In children with positive skin tests, desensitization with the measles-mumps-rubella vaccine should be done in order to administer a full dose of the vaccine. Twelve egg-allergic children, aged 12 months to 5 years of age, were referred to our pediatric allergy clinic for MMR administration over a 20-month period. Three children had positive skin prick or intradermal tests to the MMR vaccine. Two of these three patients experienced systemic hypersensitivity reactions while undergoing desensitization to the MMR. All reactions occurred with injections of the undiluted vaccine. Based upon this experience, we recommend that egg-allergic children should continue to have cutaneous tests done to the MMR vaccine and careful observation during desensitization in those children with positive skin tests

Thank you again for your inquiry and we hope this response is helpful to you.

Phil Lieberman, M.D.

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