Antibody response to booster mRNA COVID-19 vaccine after standard doses of various homologous and heterologous vaccines in kidney transplant recipients
Ahram Han1, Sangil Min1, Eun-Ah Jo1, Hye young Woo1, Ara Cho1, Hajeong Lee2, Yong Chul Kim2, Hee Kyung Kang3, Yo Han Ahn3, Eun Young Song4, Jongwon Ha1.
1Department of Surgery, Seoul National University College of Medicine, Seoul, Korea; 2Department of Internal Medicine, Seoul National University College of Medicine, Seoul, Korea; 3Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Korea; 4Department of Laboratory Medicine, Seoul National University College of Medicine, Seoul, Korea
The immune response to standard doses of COVID-19 vaccines in kidney transplant recipients (KTRs) is suboptimal and additional doses are being recommended. The type of COVID-19 vaccine one had access to during the initial standard doses of vaccination was largely dependent on its availability. Thus some had homologous vaccines (i.e. 2 doses of viral vector vaccine or 2 doses of mRNA vaccine) and others had heterologous vaccines during the initial standard vaccination. The effect of such different vaccine combinations on the effectiveness of booster shots using mRNA vaccines in KTRs is largely unknown.
The current study is a noninterventional prospective study examining the efficacy of the additional dosage of the COVID-19 vaccine in KTRs. Patients with standard doses of COVID-19 vaccines were enrolled. Reactogenicity to COVID-19 was assessed two weeks before and one month after the additional dose (booster shot) by examining anti-SARS-CoV-2 IgG antibodies against the receptor-binding domain of the S1 subunit of the spike protein using SARS-CoV-2 IgG II Quant assay (Abbott).
A total of 235 KTRs with standard doses of COVID-19 vaccine were enrolled. During the initial vaccination, 106 (45.1%) had two doses of mRNA vaccine (BNT162b2 or mRNA-1273), 73 had ChAdOX1-S/ BNT162b2 52 (22.1%) had ChAdOX1-S/ ChAdOX1-S, and one (0.4%) had Janssen COVID-19 vaccine. All patients had mRNA vaccines (BNT162b2 or mRNA-1273) for booster.
After the booster dose, seropositivity improved from 55.3% (130/235) to 81.3% (191/235) with seroconversion in 58.1% (61/105) of the initially seronegative patients. Antibody titer also was significantly increased (median, 62.3 to 1382.8 AU/mL, p<0.01 by Wilcoxon rank sum test).
Risk factors for negative antibody response to booster mRNA were low eGFR (OR 0.95, 95% CI 0.93-0.98) and having two doses of viral vector vaccines during the standard vaccination (OR 5.43, 95%CI 1.59-18.49; reference-mRNA/mRNA vaccine). This was likely due to the relatively low immunity before the third vaccine dose within this patient group (negative response in 69.2%).
The use of an additional dose of COVID-19 mRNA vaccine is effective in eliciting antibody response in KTRs, especially for those in whom the primary vaccination failed. Overall response after an additional dose of mRNA vaccine was affected by the type of vaccines used during the standard vaccination.
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