By Ed Susman, Contributing Writer – Medpage Today
SAN FRANCISCO — Some children highly allergic to milk products should be watched with caution when receiving the diphtheria, pertussis, and tetanus (DPT) vaccine because trace milk proteins in the vaccine could trigger reactions, researchers suggested.
“We identified seven patients who reported convincing allergic reactions to tetanus vaccines,” reported Scott Sicherer, MD, professor of pediatrics at the Mt. Sinai School of Medicine in New York City, during his poster presentation at the annual meeting of the American Academy of Allergy, Asthma & Immunology here.
“We observed several children with severe milk allergy to have reacted to the common childhood vaccine called the DPT or tetanus booster,” Sicherer explained in an email to MedPage Today in response to questions. “We believe that the vaccine may have very trace milk protein in some lots.”
The protein was identified as casamino acids derived from cow’s milk, contained in medium used to process the vaccines.
The findings came from a chart review of patients seen at Mt. Sinai who had reported allergic reactions after receiving the vaccine (primary or booster doses) from September 2007 to March 2010.
The patients in question, five boys and two girls, had a median age of 11.
“These cases were an observation in a relatively short period of two and one-half years where we encountered seven children with milk allergy having a severe anaphylactic reaction to the injection of the DPT shot,” said co-author Hugh Sampson, MD, director of the Jaffe Food Allergy Institute at Mt. Sinai.
“These were all children who had high levels of immunoglobulin antibody to milk protein,” Sampson remarked at a press briefing. “In two of the cases we were able to find that even though the children were from different areas they received the same lot of vaccine.”
“We then used a very sensitive immunoassay to look for the presence of milk protein in vials of Adacel which was the DPT that they received. Of the two vials we looked at, one of them clearly had milk protein in it,” he added.
“We are looking at more lots to get an idea whether this is an uncommon phenomenon or not,” Sampson said. “We were struck by the fact that just in our practice we had seven patients with milk allergy who had these severe reactions and we believe it is due to contamination of milk protein in this vaccine.”
“This is very preliminary,” Sicherer commented, “but if I had an extremely milk allergic subject I would take caution.”