02:44pm Friday 15 December 2017

Newborn screen can protect infants from vaccine-acquired rotavirus

The vaccine provides substantial benefit against rotaviral infection. Worldwide, it has prevented potentially deadly infections in millions of children. However, infants who are born lacking a protective immune system because of their genetic disorder can actually acquire the viral infection from the vaccine, the researchers said. The vaccine, given in three doses between 6 and 32 weeks of age, is live, but it has been weakened so that it does not present a threat of infection to children with normal immunity.

In this report, experts examined three cases in which infants developed rotavirus disease after receiving the live attenuated rotavirus vaccine. “All three infants (in the study) were vaccinated before they were diagnosed with severe combined immunodeficiency,” said Dr. Paula Hertel, assistant professor of pediatrics-gastroenterology at BCM and Texas Children’s Hospital, co-author of the study. “If the children could have been caught in a screening test done within days of birth, they may not have received the vaccine.”

Expanded testing

While current routine newborn screening does test for many diseases, severe combined immune deficiency is not one of them.

Usually, experts recommend that children with severe combined immune deficiency not receive live vaccines. However, this vaccine must be given before most children are diagnosed with the immune disorder. The American College of Medical Genetics recently recommended that severe combined immunodeficiency be included as a part of the newborn screen.

“The disease in these infants was confined to the gastrointestinal tract, but in other cases there is potential that it could disseminate to other organs besides the intestines,” said Dr. Stuart Abramson, associate professor of pediatrics in the section of allergy and immunology at BCM and Texas Children’s Hospital and senior author of the study.

No immune system protection

Children with severe combined immunodeficiency lack protection provided by key components of the immune system – the T- and B-cells. As a result, these children have no protection against many infections that can become life-threatening. Fortunately, the disorder is rare, affecting between 1 in 50,000 to 100,000 live births.

Scientists analyzed the viral genetic material in stool specimens from the three children. This enabled them to determine that the rotavirus was of vaccine origin. This study led to a change in the vaccine exclusions listed on the vaccine manufacturer’s label to include a history of severe combined immunodeficiency.

The children did not successfully fight the infection until they underwent bone marrow transplantation or enzyme replacement therapy that gave them a functioning immune system, said Abramson.

The vaccine is very important for healthy infants, and in the United States, rotavirus cases decreased by 50 percent after the first season of vaccinations against the illness, said Hertel.

Funding for the study came from grants from the National Institutes of Health.

Others who took part in the study include Drs. Niraj C. Patel, Mary K. Estes, Lenora M. Noroski, I. Celine Hanson, Mary E. Paul and Paula A. Revell of BCM; Dr. Maite de la Morena of University of Texas Southwestern in Dallas; Dr. Ann M. Petru of the Children’s Hospital and Research Center in Oakland; and Dr. Howard M. Rosenblatt of Dell Children’s Medical Center of Texas.

*  Dipali Pathak713-798-4710pathak@bcm.tmc.edu


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