SARS-CoV-2 Vaccination in Adolescent Solid Organ Transplant Recipients

Results of previous analyses have demonstrated that adolescent solid organ transplant recipients who receive three doses of SARS-CoV-2 mRNA vaccine experience high seroconversion rates and antibody persistence for up to 3 months. There are few data available on the long-term antibody durability in that patient population.

During a poster session at the American Transplant Congress 2023, J. McAteer and colleagues reported results of an analysis of antibody responses 6 months following the third vaccine dose of the BNT 162b2 mRNA vaccine among adolescent solid organ transplant recipients. The poster was titled Anti-Spike Antibody Durability After SARS-CoV-2 Vaccination in Adolescent Solid Organ Transplant Recipients.

The analysis included participants in a multicenter, observational cohort who received the third dose of the vaccine. Participants were analyzed for antibodies to the SARS-CoV-2 spike protein receptor-binding domain (Roche Elecsys anti-SRAS-CoV-2-S positive:  ≥0.08, maximum: >2500 U/mL). Samples were collected at 1, 3, and 6 months following dose three.

The observational cohort included 34 adolescent solid organ transplant recipients. Of those, 100% (n=34) had positive antibody titers 6 months after dose three, with a median of 2500 U/mL. Twenty-four percent (n=8/34) had decreased titers at 6 months compared with 3 months (mean decrease of 617 U/mL) and 6% (n=2/34) had increased titers (mean increase of 312 U/mL). The remaining 24 study participants (70%, n=24/34) had stable titers of >2500 U/mL from 3 to 6 months after the third dose.

Four of the 34 participants (12%) had breakthrough infection between 3 and 6 months after dose three; all of those four participants had antibody titers of >2500 U/mL at both the 3 and the 6 month time intervals. Four of the 34 (12%) reported infection at 6 to 12 months after dose three. Mean 6-month antibody titers (U/mL) were 927 among those infected 6 to 12 months after dose three versus 2174 among those not infected post dose three. At 3 months, mean antibody levels (U/mL) were 1275 among those infected 6 to 12 months after dose three (n=4) versus 2345 (n=26) among those not infected after dose three.

“In this observational cohort, antibody titers remained positive 6 months following dose three, indicating antibody durability among adolescent solid organ transplant recipients,” the authors said. “Antibody titers remained stable after receipt of dose three, with only a small subset of participants experiencing a decrease in titers compared to their 3-month post-dose three levels. Lower antibody titers at both 3 and 6 months post dose three may be associated with increased risk of breakthrough infection >6 months post dose three.”

Source: McAteer J, Abedon R R, Kalluri D D, et al. Anti-spike antibody durability after SARS-CoV-2 vaccination in adolescent solid organ transplant recipients. Poster A128. Abstract of a poster presented at the American Transplant Congress 2023; June 3-7, 2023; San Diego, California.