Korean J Transplant.  2022 Nov;36(Supple 1):S239. 10.4285/ATW2022.F-3788.

Immunogenicity of an mRNA-based COVID-19 vaccine among adolescents with obesity or liver transplants

• Tubjaroen 1 C
• Prachuapthunyachart S
• Potjalongsilp N
• Sodsai P
• Jaruampornpan P
• Chongsrisawat V

• KMID: 2535456
• DOI: http://doi.org/10.4285/ATW2022.F-3788

Abstract

Background
The mRNA-based SARS-CoV-2 vaccine (BNT162b2) is initially used in Thailand as a voluntary policy for children 12–18 years of age. There is limited data regarding the immunogenicity of this vaccine among immunosuppressed or obese individuals. This study aimed to evaluate the humoral immune response in adolescents with obesity or liver transplants (LT) after receiving two doses of BNT162b2.
Methods
Sixty-eight participants, comprising 12 LT, 24 obese and 32 healthy adolescents, were enrolled. The immunogenicity was evaluated by anti-SARS-CoV-2 spike total antibodies (Elecsys), surrogated viral neutralization test (sVNT) against two vari-ants of concern, including Delta and Omicron. The specimens were collected at baseline and 4 weeks after the second dose of vaccination. All participants were monitored for adverse events by phone call after each dose of vaccination.
Results
The median age of enrolled subjects (44 males) was 15 (range, 13–16) years. At the median time of 27 (range, 24–29) days after the second dose, the median antibody levels were 1,173 (range, 440–2,300), 2,653 (range, 1,914–4,027) and 4,166 (range, 2,634–7,687) among LT, obese and control, respectively (P<0.001). LT recipients who received mycophenolate mofetil tended to develop a lower antibody response, compared with other regimens (843.7 [440.5–2769.8] vs. 1357.5 [493.7–2300.7], P=0.83). Among obese, the presence of liver stiffness measurement greater than 5.5 kPa by Fibroscan was significantly asso-ciated with higher median antibody levels. The injection site pain was the most common local adverse event and occurred 96% after each dose. All nine participants (three obese, six control) developed a COVID-19 infection with a median time of 49 (range, 23–108) days from the second vaccination. All were mild and recovered without any consequence.
Conclusions
Our study supports that the booster regimen in specific groups, including LT recipients and obese individuals is needed. BNT162b2 is capable of reducing COVID-19 severity and is safe in adolescents.