Third vaccine boosters and anti‐S‐IgG levels: A comparison of homologous and heterologous responses and poor immunogenicity in hepatocellular carcinoma

Abstract The immune response of patients with chronic liver disease tends to be lower after receiving their second coronavirus disease 2019 (COVID‐19) vaccine dose, but the effect of a third vaccine dose on their immune response is currently unknown. We recruited 722 patients without previous severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) infection from three hospitals. The patients received homologous (MMM) and heterologous (AZAZBNT, AZAZM) boosters, where AZ, BNT, and M denoted the AZD1222, BNT162b2, and mRNA‐1273 vaccines, respectively. Serum IgG spike antibody levels were measured at a mean 1.5 ± 0.7 (visit 1) and 5.0 ± 0.5 (visit 2) months after the third vaccine booster. A threshold of 4160 AU/mL was considered significant antibody activity. In both visits, the patients who received the MMM booster had higher anti‐S‐IgG levels than those who received the AZAZBNT and AZAZM boosters. Patients with active hepatocellular carcinoma (HCC) had lower anti‐S‐IgG levels than the control group (761.6 vs. 1498.2 BAU/mL; p = 0.019) at visit 1. The anti‐S‐IgG levels decreased significantly at visit 2. The patients with significant antibody activity had a lower rate of liver cirrhosis with decompensation (0.7% decompensation vs. 8.0% non‐decompensation and 91.3% non‐liver cirrhosis, p = 0.015), and active HCC (1.5% active HCC vs. 3.7% non‐active HCC and 94.7% non‐HCC, p