Evaluation of the effectiveness and safety of sequential vaccination with inactivated SARS‐CoV‐2 vaccine and Ad5‐nCoV booster in pediatric liver transplant recipients

Abstract

AbstractAmidst the COVID‐19 pandemic, uncertainty persists among caregivers regarding the vaccination of pediatric liver transplant recipients (PLTRs). This study evaluates the immunogenicity and safety of COVID‐19 vaccination in this vulnerable population. A cohort of 30 PLTRs underwent sequential vaccinations with an inactivated SARS‐CoV‐2 vaccine followed by an Ad5‐nCoV booster. We collected and analyzed blood samples pre‐vaccination and four weeks post‐vaccination to quantify antibody and IGRA (IFN‐γ Release Assay) levels. We also documented any adverse reactions occurring within seven days post‐vaccination and monitored participants for infections over six months post‐vaccination, culminating in a comprehensive statistical analysis. The Ad5‐nCoV booster substantially elevated IgG (T1: 18.01, 20%; T2: 66.61, 55%) and nAb (T1: 119.29, 8%; T2: 3799.75, 80%) levels, as well as T‐cell responses, in comparison to the initial dose. The first dose was associated with some common adverse reactions, such as injection site pain (13.3%) and fever (16.6%), but a low rate of systemic reactions (16.0%). There was no significant difference in Omicron infection rates or RTPCR conversion times between vaccinated and unvaccinated groups. Notably, following Omicron infection, vaccinated individuals exhibited significantly higher SARS‐CoV‐2 IgG and nAb titers (average IgG: 231.21 vs. 62.09 S/CO, p = 0.0003; nAb: 5246.11 vs. 2592.07 IU/mL, p = 0.0002). The use of inactivated vaccines followed by an Ad5‐nCoV booster in PLTRs is generally safe and elicits a robust humoral response, albeit with limited T‐cell responses.