COVID-19 in solid organ transplant recipients after 2 years of pandemic: Outcome and impact of antiviral treatments in a single-center study

More than 2 years after the pandemic, the availability of vaccination and the use of monoclonal antibodies and direct antivirals have changed the fate of COVID-19, allowing for a better management of the disease, reducing hospitalization rates, and improving survival. This study aims to describe the outcome of COVID-19 in a cohort of solid organ transplant recipients and the impact of novel antivirals against SARS-CoV-2. We conducted an observational retrospective cohort study. We enrolled solid organ transplant recipients with COVID-19 attending the A.O.U. Federico II of Naples and followed up from January 2022 to July 2022. We enrolled 40 SOTs with COVID-19. Our experience highlights the favorable impact of therapies with antivirals and monoclonal antibodies in the early stages of COVID-19. Interesting data concern the impact of immunosuppressive therapy on COVID-19, in particular the role of Mycophenolate (associated with deterioration to severe COVID-19) and Everolimus (protective for progression to severe disease) needs to be investigated. Our experience also confirms the fundamental role of vaccination and in particular the importance of the booster dose.


Introduction
More than 2 years after the pandemic, the availability of vaccination and the use of monoclonal antibodies and direct antivirals have changed the fate of COVID-19 (COronaVIrus Disease- 19), allowing for a better management of the disease, reducing hospitalization rates, and improving survival. However, some categories of patients, such as immunocompromised patients, and in particular solid organ transplant patients (SOT) constitute a category of patients still at risk for a severe form of the disease (1,2). In fact, SOTs have a higher risk of COVID-19 related hospitalization, morbidity and mortality (3)(4)(5).
Moreover, considering general population of patients with COVID-19, both monoclonal antibodies and antivirals have shown excellent results in reducing both hospitalization and the mortality rate, if administered early after symptoms onset (6)(7)(8). However, data regarding the impact of these drugs in SOT recipients with COVID-19 are scarce, because most studies excluded solid organ transplants (9)(10)(11). Currently, available data are limited to a few case series describing the use of monoclonal antibodies and antivirals in SOTs (12)(13)(14)(15).
This study aims to describe the outcome of COVID-19 in a cohort of solid organ transplant recipients and the impact of novel antivirals against SARS-CoV-2 (Severe Acute Respiratory Syndrome Coronavirus 2).

Materials and methods
We conducted an observational retrospective cohort study. We enrolled solid organ transplant recipients with COVID-19 attending the A.O.U. Federico II of Naples and followed up from January 2022 to July 2022. Patients underwent rhinooropharyngeal swabs in presence of symptoms suspected for COVID-19. Diagnosis of COVID-19 was defined as positivity to the rhino-oropharyngeal swab for SARS-CoV-2 RNA research by reverse transcription-polymerase chain reaction (RT-PCR) in presence of at least one typical COVID-19 symptom (fever, malaise, cough, nausea/diarrhea, shortness of breath, headache, nasal stuffiness, anosmia, dysgeusia). To describe the clinical status of COVID-19 we used the NIAID ACTT-1 (National Institute of Allergy and Infectious Diseases Adaptive COVID-19 Treatment Trial-1) Clinical Status Ordinal Scale (16). Based on this score, we classified each patient with the infection into one of eight categories: (1) Not hospitalized, no limitations on activities; (2) Not hospitalized, limitation on activities, and/or requiring home oxygen; (3) Hospitalized, not requiring supplemental oxygen and no longer requires ongoing medical care (if hospitalization extended for infection-control purposes); (4) Hospitalized, not requiring supplemental oxygen; requiring ongoing medical care (COVID-19 related or otherwise); (5) Hospitalized, requiring supplemental oxygen; (6) Hospitalized, on noninvasive ventilation or high-flow oxygen devices; (7) Hospitalized, on invasive mechanical ventilation or ECMO; (8) Death (16).
In addition, we also distinguished patients with a mildmoderate form of COVID-19 from those with a severe form of COVID-19, based on their need of oxygen (a severe form was defined as a NIAID ACTT-1 Clinical Status Ordinal Scale score ≥ 5).
For each patient we evaluated epidemiological and clinical characteristics, laboratory and radiological data, need of hospitalization and access to the ICU (Intensive Care Unit), type of immunosuppressive treatment and the changes of immunosuppression during SARS-CoV-2 infection, treatment for COVID-19 and outcome. For each patient we evaluated SARS-CoV-2 IgG (Roche Diagnostics GmbH, Mannheim, positive threshold >15 BAU/ml) assessed at enrollment, before the infusion of monoclonal antibodies (if any). Data are presented as mean and SD or median and interquartile range (IQR), in case of Gaussian or non-Gaussian distribution, respectively. For correlation analysis, Pearson or Spearman tests were used for data distributed in Gaussian or non-Gaussian fashion, respectively. Continuous variables are compared by Student's t-test or Mann-Whitney U-Test, as parametric or non-parametric test, respectively. The p-value for statistical significance was set at <0.05 for all the tests. A logistic regression model was employed to evaluate risk factors for severe disease evolution. In particular, age, sex, comorbidities and immunosuppressive therapy were assessed and compared. The study was conducted in compliance with the Declaration of Helsinki and the principles of good clinical practice. The study was exempt from approval from an ethics' board.
Most patients (82%) with severe COVID-19 were found to be unvaccinated or vaccinated with only two doses [OR for severe COVID-. 19 Table 3).
Regarding the antiviral therapy in the early stages of the disease, in particular regarding the use of early Remdesivir and Molnupiravir in mild-moderate COVID-19, it was observed that no patient who underwent treatments showed a deterioration towards a severe disease ( Table 3).
Pooling patients who underwent all antiviral treatments in the early stages of the disease, (both direct antivirals and monoclonal antibodies), only 3 of these 29 patients (10%) developed a severe disease, compared with 8 of 11 (72%) who did not undergo such a treatment [OR for severe COVID-19: 0.7, 95, CI: (0.5-0.8) antiviral early treatment vs. no early antiviral treatment; p = 0.036]. At multivariate analysis, the use of early antiviral treatments was confirmed to be independently associated with a reduced risk of developing severe disease [OR for severe COVID-19: 0.8, 95, CI: (0.5-0.9); p = 0.041] Table 4.

Discussion
First of all, our study shows that after 2 years of pandemic the hospitalization rate and the mortality rate of SOTs with COVID-19 have decreased. In fact, while at the beginning of the pandemic it was estimated a hospitalization rate of about 32%-100% (18-20) and a mortality rate of about 13%-30% (21), after 2 years, from our study there was a hospitalization rate of about 27% and a mortality rate of about 10%. These data are in agreement with those reported by Heldman and colleagues, who showed that hospitalization rate and the mortality rate in SOTs were gradually decreasing (22). Probably, this change is due to the higher awareness and higher ability to manage COVID-19, thanks to the availability of various therapeutic resources that have occurred over time. However, although reduced, the hospitalization rate and the mortality rate remain quite high in this category of patients.   (24).
At the same time, an elevated CRP (CPR > 5 mg/dl) and lymphopenia (lymphopenia described as lymphocyte < 800 cell/ mm 2 ) were confirmed as predictors of a possible evolution of the disease in a severe form (25,26).
The type of SOT and the time after transplantation did not constitute a risk factor for severe disease (OR 1.1, 95%, CI: 0.7-2.1], p = 0.210 and OR 1.3, 95%, CI: 0.9-1.5], p = 0.130). These data were comparable to that is reported by Pereira (36). However, our own data are not in agreement to what has been reported by Genuardi et al. (37). In this study, in fact, -inhibitor use was shown to be an independent risk factor for severe COVID-19 [OR 6.80 (95% CI 1.30-41.00), p = 0.026]. However, it is noteworthy that Genuardi's study included only heart transplant patients and only 15 were patients who practiced therapy with mTOR inhibitors (37). At the same time, there are studies that did not find any role of mTOR inhibitors in the evolution of COVID-19 (38,39).
Calcineurin inhibitors were confirmed as non-risk factors for disease severity, as reported in the literature (33,37).
In consideration of the few data in the literature concerning the use of antivirals in SOTs, our study showed the impact of antivirals, in particular it highlighted how the use of antivirals in the early stages of mild-moderate disease was associated with a lower risk of developing severe disease (OR for early Remdesivir vs. no early Remdesivir: 0.8, 95, CI: (0.6-0.9) severe COVID-19 vs. mild-moderate COVID-19; p = 0.044; OR for Molnupiravir vs. no Molnupiravir: 0.7, 95, CI: (0.4-0.9) severe COVID-19 vs. mildmoderate COVID-19; p = 0.035) ( Table 3). We underline that in this cohort of patients we considered only the use of early Remdesivir and Molnupiravir, due to the potential drug interactions nirmatrelvir/ritonavir with immunosuppressive therapy and others concomitant therapies. Our data were confirmed by several studies, in fact the data regarding early Remdesivir treatment in SOT agreed with the study by Colaneri et al., in which treatment with early Remdesivir was shown to prevent severe COVID-19 [HR: 0.05; C.I. (0.00-0.65), p = 0.01i] (14). At the same time Villamarín et al. showed how the use of Molnupiravir in SOTs could reduce the risk of hospitalization and mortality, confirming our data (40). However, we underline that currently data on the use of antivirals in SOTs are scarce and scanty so far.
Regarding monoclonal antibodies, in our study the use of Casirivimab/Imdevimab (600 mg/600 mg) and Sotrovimab (500 mg) in the early stages of the disease was also associated with a lower risk of developing severe disease. However, the use of Casirivimab/Imdevimab had no significant impact on outcome [OR for severe COVID-19 vs. mild-moderate COVID-19: 0.9, 95, CI: (0.8-1.1) Casirivimab/Imdevimab 600 mg/600 mg vs. no Casirivimab/Imdevimab 600 mg/600 mg; p = 0.057] and this is probably attributable to the small number of individuals considered (n. 3). In contrast, the use of Sotrovimab was associated with a lower risk of developing severe disease [OR for severe COVID-19 vs. mild-moderate COVID-19: 0.7, 95, CI: (0.5-0.9) Sotrovimab vs. no Sotrovimab:; p = 0.038]. Our data agree with what has been already reported by Gueguen et al. which showed that SOTs subjected to monoclonals had a lower hospitalization rate (35% vs. 49.7%, p = 0.032) and a lower mortality (1.25% vs. 11.6%, p = 0.005) compared to those who did not practice treatment with monoclonals (41,42). In the study of Headvat J et al., patients who received Sotrovimab (N = 51) experienced a lower rate of 30-day hospitalization or death as compared to those who received no specific treatment (N = 75) (p = 0.009) (9). Similar results were also reported by Cochran et al. and also from our previous experience, which showed that treatment with Sotrovimab significantly was associated with a low risk of developing a severe disease (12,43). Regarding the choice of the different monoclonal antibodies, we underline that this should be related to the circulating variants. In fact the advent of the Omicron variant, and in particular of the BA.1 variant, led to a main use of sotrovimab, due to the reduced activity and efficacy of the other monoclonal antibodies against this variant (43,44). Subsequently, with the advent of the BA.2 variant led to a reduction of use of sotrovimab due to its reduced activity towards this new variant (44).
Our study shows a significant and favorable impact of antiviral therapies used in the early stages of COVID-19 in SOTs, highlighting how direct antiviral therapies and monoclonal antibodies have changed the evolution and fate of the disease. Our study underlines the importance of timely intervention with these therapies in the early stages of COVID-19, as they allow us to reduce the risk of severe disease evolution.
We acknowledge that our study has several limitations, in particular they are: small number of the sample, single-center retrospective observational study, the absence of a control group and the consideration of only patients with COVID-19 and not all SOTs with SARS-CoV-2 infection.
The main strength of our study is the topical update of the data in a time of availability of several weapons against COVID-19, such as antivirals and monoclonal antibodies, allowing a current view of disease in SOTs.

Conclusion
Our study, albeit monocentric and with a small number of subjects considered, offers an overview of what the current status of COVID-19 in SOTs at about 2 years after the start of the pandemic. In particular, our real-life experience highlights the favorable impact of therapies with antivirals and monoclonal antibodies in the early stages of COVID-19. However, further studies are needed to investigate and confirm these data. Interesting data concern the impact of immunosuppressive therapy on COVID-19, in particular the role of Mycophenolate (associated with deterioration to severe COVID-19) and Everolimus (protective for progression to severe disease) needs to be investigated. Our experience also confirms the fundamental role of vaccination and in particular the importance of the booster dose. Despite all these weapons, our study underlines that SOTs are still to be considered a category of patients at high risk for developing severe COVID-19.

Data availability statement
The raw data supporting the conclusions of this article will be made available by the authors, without undue reservation.

Ethics statement
The studies involving human participants were reviewed and approved by The study was approved by the "Federico II" Ethics Committee. The patients/participants provided their written informed consent to participate in this study.