Incidence and severity of SARS-CoV-2 infections in liver and kidney transplant recipients in the post-vaccination era: Real-life data from Denmark

Abstract

Coronavirus disease 2019 (COVID-19) caused by SARS-CoV-2 has been associated with a high risk of adverse outcomes in solid organ transplant (SOT) recipients in the pre-vaccination era. In this retrospective cohort study, we examined the incidence and severity of COVID-19 in kidney and liver transplant recipients in Denmark in the post-vaccination era, from December 27, 2020, to December 27, 2021. We included 1428 SOT recipients with 143 cases of first-positive SARS-CoV-2 PCR test. The cumulative incidence of first-positive SARS-CoV-2 PCR test 1 year after initiation of vaccination was 10.4% (95% CI: 8.8-12.0), and the incidence was higher in kidney than in liver transplant recipients (11.6% [95% CI: 9.4-13.8] vs. 7.4% [95% CI: 5.1-9.8], p = .009). After the first-positive SARS-CoV-2 PCR test, the hospitalization rate was 31.5% (95% CI: 23.9-39.1), and 30-day all-cause mortality was 3.7% (95% CI: 0.5-6.8). Hospitalization was lower in vaccinated than in unvaccinated SOT recipients (26.4% [95% CI: 18.1-34.6] vs. 48.5% [95% CI: 31.4-65.5], p = .011), as was mortality (1.8% [95% CI: 0.0-4.3] vs. 9.1% [95% CI: 0.0-18.9], p = .047). In conclusion, SOT recipients remain at high risk of adverse outcomes after SARS-CoV-2 infections, with a lower risk observed in vaccinated than in unvaccinated SOT recipients.

Keywords: clinical research/practice; infection and infectious agents - viral: SARS-CoV-2/COVID-19; infectious disease; patient survival; solid organ transplantation; vaccine.

FIGURE 1

Consort diagram. A flow diagram showing how many SOT recipients were eligible to be included in the study cohort and the reasons for exclusion in SOT recipients not included.

FIGURE 2

Cumulative incidence of first-positive SARS-CoV-2 PCR test in kidney and liver transplant recipients during the study period (December 27, 2020 to December 27, 2021). Cumulative incidence of first-positive SARS-CoV-2 PCR test in kidney (gray) and liver (red) transplant recipients from December 27, 2020 to December 27, 2021 excluding participants with delayed entry. In Denmark, the alpha variant was first reported in November 2020, and from March until June 2021 it was the dominant variant. The delta variant became the dominant variant from July 2021 until December 2021, and the first cases of omicron were detected in late November 2021. [Color figure can be viewed at wileyonlinelibrary.com]

FIGURE 3

Cumulative incidence of hospitalizations, ICU admissions, and mortality 30 days after first-positive SARS-CoV-2 PCR test in vaccinated and unvaccinated SOT recipients. (A) Cumulative incidence of hospitalizations in vaccinated and unvaccinated SOT recipients due to COVID-19 in the first 30 days after positive SARS-CoV-2 PCR test with day of first-positive SARS-CoV-2 PCR test as day 0. (B) Cumulative incidence of ICU admissions in vaccinated and unvaccinated SOT recipients due to COVID-19 in the first 30 days after first-positive SARS-CoV-2 PCR test with day of first-positive SARS-CoV-2 PCR test as day 0. (C) All-cause mortality in vaccinated and unvaccinated SOT recipients in the first 30 days after first-positive SARS-CoV-2 PCR test with day of first-positive SARS-CoV-2 PCR test as day 0. The yellow line represents SOT recipients who were vaccinated at time of infection, while black line represents SOT recipients who were unvaccinated at time of infection. [Color figure can be viewed at wileyonlinelibrary.com]

FIGURE 4

Cumulative incidence of hospitalizations, ICU admissions, and mortality 30 days after first-positive SARS-CoV-2 PCR test in kidney and liver transplant recipients. (A) Cumulative incidence of hospitalizations in SOT recipients due to COVID-19 in the first 30 days after first-positive SARS-CoV-2 PCR test with the day of first-positive SARS-CoV-2 PCR test as day 0. (B) Cumulative incidence of ICU admissions in liver and kidney transplant recipients in the first 30 days after first-positive SARS-CoV-2 PCR test with the day of first-positive SARS-CoV-2 PCR test as day 0. (C) All-cause mortality in liver and kidney transplant recipients in the first 30 days after first-positive SARS-CoV-2 PCR test with day of first-positive SARS-CoV-2 PCR test as day 0. The red line represents liver transplant recipients and the grey line represents kidney transplant recipients. [Color figure can be viewed at wileyonlinelibrary.com]