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Kidney Week

Abstract: PO2094

Antibody Response to SARS-CoV-2 mRNA Vaccines in Pediatric Kidney Transplant Recipients

Session Information

Category: Transplantation

  • 1902 Transplantation: Clinical


  • Crane, Clarkson, University of California San Diego, La Jolla, California, United States
  • Ingulli, Elizabeth G., University of California San Diego, La Jolla, California, United States

In the general population, mRNA SARS-CoV-2 vaccines are highly efficacious and patients form an antibody to S1 subunit of the SARS-CoV-2 spike protein. Early reports suggest a decreased antibody response in immunosuppressed adult solid organ transplant (SOT) patients. However, the serologic response in adolescent SOT patients has not yet been characterized.


Kidney transplant recipients (KTR) at our center who received both doses of an mRNA SARS-CoV-2 vaccine had SARS-CoV-2 spike protein antibody presence evaluated 4-8 weeks after their second dose of the vaccine as part of routine clinical care. We utilized the Abbott chemiluminescent microparticle immunoassay or Siemens Atellica IM SARS-CoV-2 IgG. Patients were characterized as vaccine responders or non-responders.


Of 47 vaccine-eligible KTR in our program, 34 received both doses of a SARS-CoV-2 mRNA vaccine. Twenty-three patients had spike antibody titers obtained. The median age was 21.5 years and all except one were transplanted over 3 years ago. Twenty-two received Pfizer-Biontech vaccine and one received Moderna. Twelve patients (52%) had a positive spike antibody. Of those who responded, eight patients’ immunosuppression regimens included mycophenolate (mean dose 719 mg/m2/day), three were treated with azathioprine and one was not taking an antimetabolite due to EBV viremia. All non-responders were treated with mycophenolate (average dose 755 mg/m2/day). Three patients had prior COVID-19 infection, and all had a positive antibody response.


Our results suggest vaccine response in adolescent KTR is suboptimal and lower than the general population. However, 52% response rate is similar to that previously described in adult SOT patients. While our study is limited by small sample size and lack of standardized timing for measuring antibodies, it provides further evidence of lower immunogenicity to SARS-CoV-2 vaccination in SOT. Those who did not respond tended to have a higher average dose of mycophenolate and this supports further study of alternative antimetabolite dosing strategies around the time of vaccination or the potential utility of a third vaccine dose in SOT patients. At our center, efforts to continue characterizing antibody response of pediatric KTR are ongoing and we anticipate additional data in the coming months as vaccine eligibility expands to younger patients.