Measles vaccine is an attenuated live virus vaccine cultured on chick embryo fibroblasts. Much controversy exists concerning its use in egg-allergic children.
< 71.6/million doses (life-threatening anaphylactic reactions).
Allergic reactions to food gelatin.
Egg allergy: controversial
Anaphylactic shock, cough, wheezing, urticaria, angioedema.
Non-immediate mild skin eruptions (several to 48 hours after vaccination).
Cutaneous testing (controversial): patients with or without allergy may have positive skin test reactions to the vaccine and still be safely immunized.
Specific IgE to gelatin (immunoblotting, UniCAPâ/Pharmacia CAP System, fluorimetric ELISA).
Gelatin specific cell mediated immunity: in vitro lymphocyte proliferation assay, antigen specific IL 2 responsiveness (non immediate reactions to gelatin).
IgE-mediated hypersensitivity due to the presence of minute quantities of ovalbumin (37 to 260 pg).
Neomycin: few cases (controversial).
Gelatins: numerous papers show a strong relationship between systemic immediate-type allergic reactions to vaccine and the presence of specific IgE to gelatins.
Measles vaccine containing the Edmoston-Zagreb strain (grown in human diploid cells) has lower immunogenicity than the Schwarz strain grown in a chick embryo fibroblast culture.
Up to now (1997), 1326 egg-allergic children who received the Schwarz strain measles vaccine suffered no allergic reactions, whereas 43 non egg-allergic children showed immediate reactions after the immunization.
In egg-allergic patients, some doctors perform skin prick-tests with vaccine (1/10).
- if positive administer subcutaneously 0.05 ml at 1/100, 1/10, pure up to a total dose of 0.5 ml (at 15 minute intervals)
- if negative perform an intradermal tests with measles vaccine 1/100
if positive, proceed in the same way as for a positive prick-test
if negative, administer the total dose of vaccine, i.e. 0.5 ml subcutaneously under medical supervision (30 minutes).
This protocol is contested by many authors who prefer the following recommendations:
- all immunizations should be performed by those capable of managing vaccine-associated anaphylaxis.
- egg allergy is not a contraindication to immunization with MMR. In individuals with a history of anaphylaxis to eggs, measles immunization may be routinely administered nner without prior skin testing. Immunization should be performed where adequate facilities are available to manage anaphylaxis. At-risk patients should be observed for 30 minutes.
- Measles vaccine or MMR is contraindicated in individuals with a previous anaphylactic reaction to vaccine containing measles.
- Observation for post measles-vaccine anaphylaxis should be improved, and prospective studies should be initiated to better define the risk in individuals with egg allergy.