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AAAAI: Rotavirus Vaccine May Cause Infections in SCID Kids
WASHINGTON, March 17 -- The rotavirus vaccine recommended for all infants can cause infection in babies with severe immunodeficiencies, a researcher said here.
* Explain to interested patients that a three-dose schedule of rotavirus vaccine, which contains live but genetically weakened virus strains, is recommended for all infants beginning at two months of age.
* Explain that severe combined immunodeficiency is extremely rare, but when it occurs, it is frequently not diagnosed until the child is several months old.
* Explain that infections caused by other live-virus vaccines have been found in immunodeficient children.
* Note that this study was published as an abstract and presented orally at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.
Two infants receiving the first two of three scheduled doses of the live, attenuated-virus rotavirus vaccine (RotaTeq) developed infections traced to the product, according to Niraj C. Patel, M.D., of Baylor College of Medicine in Houston.
After the babies were hospitalized with diarrhea and other symptoms consistent with rotavirus infection, it was discovered that they had severe combined immunodeficiency syndrome (SCID).
These are the first reported cases of infection caused by the rotavirus vaccine, which was approved in 2006, Dr. Patel said in a late-breaking research session here at the American Academy of Allergy, Asthma, and Immunology meeting.
Dr. Patel said molecular analyses showed that the vaccine caused the infections. All the attenuated virus strains used in the vaccine contain two bovine genes that aren't found in wild-type human rotavirus. Both were present in the rotavirus isolates obtained from the babies.
The CDC recommends that the vaccine be given to all infants at two, four, and six months of age. Both infants who developed infections received the first two doses on schedule.
One case involved a girl hospitalized for pneumonia and respiratory infection from two weeks to two months of age; SCID was not immediately recognized. About a month after the second dose, she was rehospitalized with diarrhea, acidosis, and failure to thrive.
The other case was a boy who developed diarrhea, dehydration, and shock six days after the second vaccination.
Dr. Patel noted that other live-pathogen vaccines -- poliovirus, BCG, measles, and varicella -- have also been found to cause infection in children with SCID.
The condition occurs in about one in 500,000 to 1 million births. The Immune Deficiency Foundation estimates that the median age at diagnosis is about 24 weeks -- well after infant vaccinations are supposed to begin.
There is currently no standard, reliable screening test for SCID, Dr. Patel said. It is usually diagnosed when infants present with repeated and/or unusual infections. Lymphopenia is a warning sign, but "it is not very specific," he said.
The molecular analysis of the infants' viral isolates indicated that the vaccine strains underwent mutation to cause disease.
That may explain why the infections did not develop immediately after the first dose in either case. "[The virus] perhaps took some time to mutate before causing disease," he said.
Session moderator A. Wesley Burks, M.D., of Duke University in Durham, N.C., commented that the clinical implications are still uncertain.
"We [still] have to understand what the right thing to do is," he said.
"Immune deficiency is not common, but at the same time it happens. Children [with it] that get a live viral vaccine, they're going to have trouble with it."
Both he and Dr. Patel suggested that a reliable screening test for infant immunodeficiencies is needed to avert future infections associated with live-virus immunizations.
No external funding for the study was reported.
Dr. Patel reported no potential conflicts of interest. Dr. Burks reported relationships with Acto-GeniX NV, Allertein, Dannon Co. Probiotics, EpiPen/Dey L.P., Genentech, Novartis, Nutricia, McNeil Nutritionals, Mead Johnson, MastCell Inc., and Gerber.
Primary source: American Academy of Allergy, Asthma & Immunology
Patel N, et al "Vaccine-acquired rotavirus infection in two infants with severe combined immunodeficiency" AAAAI 2009; Abstract L29.