Pediatric transplant recipients mount a more robust immune response after two COVID-19 vaccine doses

In a study published today in the American Journal of Transplantation, Johns Hopkins Medicine researchers say that children between the ages of 12 and 18 who have undergone a solid organ transplant appear to mount a stronger immune response than their adult counterparts after a standard dose. of two doses. vaccination schedule against SARS-CoV-2, the virus that causes COVID-19.

We found that nearly three quarters of the pediatric transplant recipients we studied had a positive and protective antibody response after receiving two doses of the Pfizer/BioNTech messenger RNA [mRNA] vaccine, unlike many adult transplant recipients evaluated in previous Johns Hopkins Medicine trials who required a third dose.”

Douglas Mogul, MD, Ph.D., MPH, senior author of the study, associate professor of pediatrics at Johns Hopkins Children’s Center and Johns Hopkins University School of Medicine

People undergoing solid organ transplants (such as hearts, lungs, and kidneys) often have to take medications to suppress their immune systems and prevent rejection. Such regimens may interfere with a transplant recipient’s ability to make antibodies against foreign substances, including the protective ones produced in response to vaccines.

When researchers at Johns Hopkins Medicine previously looked at the COVID-19 vaccine response of adult transplant recipients, they found in one study that only 17% of participants produced sufficient antibodies after one dose of either the Pfizer/BioNTech or Moderna vaccine. mRNA vaccine. Then, in a second study, they found that levels improved to 54% after a second injection. In both studies, even the transplant recipients who produced antibodies had levels (known as antibody titers) well below the levels typically seen in people with healthy immune systems.

A third study from Johns Hopkins Medicine looked at the immune response of adult transplant recipients after a third dose of mRNA vaccine. The findings revealed that a third of those who had negative antibody levels and all who had low positive levels before the booster shot increased their immune response afterward.

In the latest study, participants were 57 pediatric solid organ transplant recipients who had received the Pfizer/BioNTech vaccine. The median age was 14 (ranged between 12 and 18 years old), 40% were male, and 74% were Caucasian. Patients had a median of 10 years (range 5 to 13 years) since their transplant surgery and liver transplants (44%) were the most common type. Some patients took more than one immunosuppressive medication to prevent rejection of their transplanted organs.

Positive antibody levels to SARS-CoV-2 were seen in 73% of 45 children with available samples after two vaccine doses. Of the 30 whose antibody titers were measured after both the first and second injection, 17% had negative titers after both, 33% had a negative titer turning positive, and 47% had positive titers throughout. One patient who had a positive titer after one dose who became negative after the second (3%).

Negative antibody levels after two vaccine doses were most often seen in those patients who had received their transplanted organ within three years prior to vaccination, had taken multiple immunosuppressive medications, or were taking an antimetabolite immunosuppressant (a drug that kills immune cells by mimicking the metabolites they need). have to survive).

The researchers report that no organ rejection or other unexpected side effects were seen in the study participants. Two patients tested positive for SARS-CoV-2 infection during the study.

“Our preliminary findings suggest the possibility that the standard two-dose regimen for mRNA vaccines is safe in pediatric transplant recipients,” said study lead author and Johns Hopkins medical student Caroline Qin. “Further research is needed to demonstrate whether two doses provide clinical protection and if not, the role a third dose may play in boosting the immune system of those who fail to respond after two doses.”

Along with Mogul and Qin, Johns Hopkins Medicine team members are Olga Charnaya, John McAteer, Ashley Thomas, Teresa Chiang, Jacqueline Garonzik-Wang and Dorry Segev. Other institutions participating are Scott Auerbach and Amy Feldman, Children’s Hospital Colorado; Lara Danziger-Isakov, Cincinnati Children’s Hospital Medical Center; Noelle Ebel, Lucile Packard Children’s Hospital Stanford; Evelyn Hsu, Seattle Children’s Hospital; Saeed Mohammad, Ann and Robert H. Lurie Children’s Hospital of Chicago; and Emily Perito, University of California San Francisco Benioff Children’s Hospital.

The study was supported by a donation from the Ben-Dov family, grant K24AI144954 from the National Institute of Allergy and Infectious Diseases, and grant K08 H2026510-01A1 from the Agency for Healthcare Research and Quality.


Reference magazine:

Qin, CX, et al. (2021) Antibody response to 2-dose SARS-CoV-2 mRNA vaccination in pediatric solid organ transplant recipients. American Journal of Transplantation.

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