Most liver transplant recipients mount adequate COVID-19 antibody response
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The majority of liver transplant recipients are able to produce a functional antibody response to COVID-19 infection, according to data published in Gut.
“Our findings suggest that the humoral response of [liver transplant (LT)] recipients is only slightly lower than expected compared with that of COVID-19 immunocompetent controls,” Chiara Becchetti, MD, of the department of visceral surgery and medicine at the University of Bern in Switzerland, and colleagues wrote. “Additionally, we showed that the majority of LT recipients is capable of mounting an adequate neutralizing activity against SARS-CoV-2 and that neutralizing ability was associated with the presence of antinucleocapsid antibodies.”
Becchetti and colleagues recruited 35 LT recipients with SARS-CoV-2 and compared them with two control groups: 35 immunocompetent patients with SARS-CoV-2 infection and 70 LT recipients without a SARS-CoV-2 diagnosis. Researchers collected information regarding date of infection, COVID-19-related symptoms, indication for LT, time since LT, comorbidities and immunosuppressive therapy to compare the differences in antibody response between groups.
According to the study, 80% of patients in the COVID-19 LT cohort developed a “detectable antinucleocapsid antibody titer,” despite the use of immunosuppressive drugs. However, with a median IgG index level of 3.73, compared with 7.36 in the COVID-19 immunocompetent control group, the response was significantly lower (P < .001). In the LT recipient control group, only one patient, who had reported no recent COVID-19-related symptoms and had not been in contact with anyone who tested positive, had a detectable positive response.
The researchers found no significant difference in the positivity rate of anti-S antibody response between the COVID-19-LT (97.1%) and COVID-19-immunocompetent cohorts (100%) but found neutralizing activity in 82.9% of LT recipients compared with 100% in the COVID-19-immunocompetent cohort (P = .024). These findings may be explained, Beccheti and colleagues wrote, by the fact that the anti-S antibody test that was used is more sensitive than the antinucleocapsid test.
“LT patients have a less severe impairment of the immune response to SARS-CoV-2 than previously thought, and antinucleocapsid antibodies may indirectly indicate which patients are able to mount functional antibodies to neutralize the virus,” researchers wrote. “Caution must be taken when interpreting the results of testing for anti-S antibodies, since those results can overestimate the ability of neutralizing the virus on subsequent exposure.”