Discussion
In our study, patients who applied to our liver transplant outpatient clinic were evaluated in terms of serum SARS-COV-2 Ig M + IgG level and history of COVID-19 disease. The Serum antibody positivity rate was 30.7% in liver transplant patients participating in our study. The seroprevalence values for the region in which we conducted the current study are unknown. However, seropositivity was found to be 12.3% (115/932) in a seroprevalence study conducted on healthcare professionals in Turkey. The seropositivity among previously undiagnosed healthcare workers was calculated as 2.7% [4].
Limited data are available for asymptomatic or subclinical infections in the transmission of the SARS-CoV-2 virus [5]. In our study, the rate of participants with an asymptomatic history of covid-19 was 7.6% (7/91). Seventy-five percent of all antibody-positive patients were not diagnosed with COVID-19, and their inquiries had no specific symptoms of COVID-19. When all participants were evaluated, 23% (21/91) subclinical or asymptomatic seropositivity was detected.
In previous studies, acute and past SARS-COV-2 infections were documented in 3.7% of LT recipients. In the same study, the asymptomatic seropositivity rate was evaluated as 62.5% (5/8) [6]. The rate of asymptomatic COVID-19 in liver transplant recipients has been determined by 6% in the Spain series and 14% in a multinational study (n = 151) [7, 8].
In our study, 66% of patients with seropositive (14/21) were utterly asymptomatic; at least one symptom was observed in seven participants. However, there was no significant difference between the symptoms of both groups.
There was no difference between serum AST and ALT levels in patients with seropositive and seronegative. But we do not know serum AST and ALT values in possible disease processes. Studies have been shown to be a relationship between severe disease and elevated liver enzymes in patients with COVID-19. In infected individuals with SARS-COV-2, increased serum liver enzyme levels had seen approximately 15% [9]. In our clinical data, serum AST or ALT levels were found to be two times or higher in 23% of patients diagnosed with symptomatic covid (n=4/17). Increased liver enzymes are usually reversible. As expected, seropositivity is not associated with alone increased liver enzymes.
Asymptomatic or subclinical COVID-19 participants with seropositivity include the history of risky contact with people diagnosed COVID-19 in 19% and the history of hospitalization in 28%. In contrast to the expected, the higher rate of seropositivity was not associated with contact with risky people or hospitalization.
Our limitation of the study is that patients are evaluated in a wide period of 6 months to determine seroprevalence as serum antibody tests are observed during routine follow-up.
In conclusion, studies related to the course of the disease in liver transplant recipients are increasing gradually. However, the frequency of asymptomatic or subclinical disease is not precise yet. Although the number of patients in our study was low, the seropositivity rate (30.7%) and the rate of asymptomatic (75%) among all the participants were higher than expected. We need large-scale seroprevalence studies to reach more reliable data.