Correspondence on Letter regarding “COVID-19 vaccine immunogenicity among chronic liver disease patients and liver transplant recipients: A meta-analysis”

Article information

Clin Mol Hepatol. 2023;29(1):176-178

Publication date (electronic) : 2022 November 10

doi : https://doi.org/10.3350/cmh.2022.0377

Ka Shing Cheung^1,2, Chiu Hang Mok³, Wai Kay Seto^,1,2,4, Man Fung Yuen^,1,4

¹Department of Medicine, School of Clinical Medicine, The University of Hong Kong, Queen Mary Hospital, Hong Kong

²Department of Medicine, The University of Hong Kong-Shenzhen Hospital, Shenzhen, China

³School of Clinical Medicine, The University of Hong Kong, Hong Kong

⁴State Key Laboratory of Liver Research, The University of Hong Kong, Hong Kong

Corresponding author : Man Fung Yuen Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Pokfulam Road, Hong Kong Tel: +852-22553984, Fax: +852-28162863, E-mail: mfyuen@hkucc.hku.hk

Wai Kay Seto Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Pokfulam Road, Hong Kong Tel: +852-22556979, Fax: +852-28725828, E-mail: wkseto@hkucc.hku.hk

Editor: Seung Up Kim, Yonsei University College of Medicine, Korea

Received 2022 November 5; Accepted 2022 November 7.

Dear Editor,

We would like to thank Mungmunpuntipantip and Wiwanitkit [1] for their response to our recent meta-analysis [2] on the possible confounding factors of vaccine recipients, including underlying medical conditions and prior coronavirus disease 2019 (COVID-19) infection. COVID-19 infection can cause not only gastrointestinal symptoms but also hepatic injury, including cholangitis and autoimmune hepatitis [3,4]. Therefore, vaccination is of paramount importance to prevent COVID-19 infection and its disease severity.

We agree that patients with more comorbidities may have different vaccine immunogenicity compared to healthy individuals. Table 1 shows the list of comorbidities among patients included in our analysis. No study provided individual data for the outcome of seroconversion regarding the presence of comorbidity. Importantly, non-alcoholic fatty liver disease, which may affect vaccine immunogenicity [5], is also associated with a higher risk of comorbidities, such as diabetes mellitus. Unlike the etiology of liver disease and cirrhosis status, wherein we used a prevalence of 80% as the cut-off for classification, the data for comorbidity were heterogenous and no cut-off could be drawn. Hence, we could not perform subgroup analysis with respect to each comorbidity. In addition, certain medications (e.g., antibiotics, angiotensin-converting enzyme inhibitors, histamine 2 receptor antagonists) may affect either the COVID-19 vaccine response [6] or disease severity [7,8]. However, drug data were lacking in the included studies.

Table 1.

Comorbidities of patients in the included studies

Although prior history of COVID-19 infection was part of the exclusion criteria in our study, asymptomatic cases might have been enrolled, as the baseline levels of antibodies were measured. Timmermann et al. [9] found 2/120 asymptomatic patients with positive anti-nucleocapsid-immunoglobulin G antibodies, and these patients were excluded from subsequent analysis. A meta-analysis revealed that 0.25% of the tested general population were asymptomatic infections [10]. Nevertheless, this issue may not have a significant impact on our results due to a large sample size of 3,945 patients. It is noteworthy that vaccinated recipients, especially liver transplant patients, should still adhere to other infection prevention and control measures, such as social distancing [11].