Seroconversion following SARS-CoV-2 Infection or Vaccination in Pediatric IBD Patients

Objective

Inflammatory bowel disease (IBD) patients are commonly treated with immunomodulatory medications, and the effect of these medications on seroconversion to SARS-CoV-2 infection and vaccination are scant, particularly in pediatrics. We sought to determine serologic responses to SARS-CoV-2 infection and vaccination in pediatric IBD patients.

Design

We conducted a single-center, retrospective study of all pediatric (≤21 years old) IBD patients in whom a SARS-CoV-2 IgG Antibody Assay was performed between April 2020 and May 2021 at our tertiary care center. This assay measures IgG antibody to the full-length SARS-CoV-2 spike protein and was routinely collected at infusion and outpatient clinic visits. The primary outcome was SARS-CoV-2 seroconversion, and the secondary outcome was titer level, with high titer defined as ≥960 titer or >40 AU/mL. Clinical characteristics, including demographics, IBD location, behavior, activity, and therapy, SARS-CoV-2 exposures, COVID-19 testing and symptoms, SARS-CoV-2 infection status (WHO COVID-19: Case Definitions, 2020) and COVID-19 vaccination status and type, were gathered, and univariate analyses examined associations between clinical characteristics and outcome measures.

Results

There were 340 pediatric patients with SARS-CoV-2 Antibody Testing; 15% for confirmed or probable COVID-19, 2% for suspected COVID-19, 16% for asymptomatic exposure to a close contact with SARS-CoV-2 infection, 61% without any prior symptoms or exposures, and 6% for history of COVID-19 vaccination. Patients with confirmed or probable COVID-19 infection had a 90% rate of seroconversion, with 76% of these patients on biologic therapy. Patients post-infection without seroconversion had a significantly longer interval between infection and antibody assay (P=0.03). Within those with asymptomatic SARS-CoV-2 exposure, 43% had seroconversion, and there were no identified clinical characteristics associated with positive titer.

All pediatric patients who received vaccination seroconverted, and all who received mRNA vaccinations, including one after a single dose, achieved high titer levels; 100% of those who received vaccination were on biologic or small molecule therapy, including one on combination therapy with ustekinumab and tofacitinib.

Conclusion

Pediatric IBD patients have strong serologic antibody responses to SARS-CoV-2 infection and COVID-19 vaccination despite high rates of immunomodulatory therapy.