Inherited human RelB deficiency impairs innate and adaptive immunity to infection.

We report two unrelated adults with homozygous (P1) or compound heterozygous (P2) private loss-of-function variants of V-Rel Reticuloendotheliosis Viral Oncogene Homolog B (RELB). The resulting deficiency of functional RelB impairs the induction of NFKB2 mRNA and NF-κB2 (p100/p52) protein by lymphotoxin in the fibroblasts of the patients. These defects are rescued by transduction with wild-type RELB complementary DNA (cDNA). By contrast, the response of RelB-deficient fibroblasts to Tumor Necrosis Factor (TNF) or IL-1ß via the canonical NF-κB pathway remains intact. P1 and P2 have low proportions of naïve CD4+ and CD8+ T cells and of memory B cells. Moreover, their naïve B cells cannot differentiate into immunoglobulin G (IgG)- or immunoglobulin A (IgA)-secreting cells in response to CD40L/IL-21, and the development of IL-17A/F-producing T cells is strongly impaired in vitro. Finally, the patients produce neutralizing autoantibodies against type I interferons (IFNs), even after hematopoietic stem cell transplantation, attesting to a persistent dysfunction of thymic epithelial cells in T cell selection and central tolerance to some autoantigens. Thus, inherited human RelB deficiency disrupts the alternative NF-κB pathway, underlying a T- and B cell immunodeficiency, which, together with neutralizing autoantibodies against type I IFNs, confers a predisposition to viral, bacterial, and fungal infections.

Safety but limited efficacy of donor lymphocyte infusion for post-transplantation cyclophosphamide-treated patients.

The therapeutic efficacy of donor lymphocyte infusions (DLIs) given after allogeneic hematopoietic cell transplantation (HCT) is limited by risk of graft-versus-host disease (GVHD). Post-transplantation cyclophosphamide (PTCy) effectively prevents severe GVHD, but there are limited data on outcomes of DLIs given to PTCy-treated patients. We reviewed 162 consecutive PTCy-treated patients transplanted between 2015-2022 within the Center for Immuno-Oncology at the National Cancer Institute. Of 38 DLIs given to 21 patients after 22 HCTs, few DLIs were associated with toxicities of acute GVHD (7.8%), cytokine release syndrome (CRS, 7.8%), or chronic GVHD (2.6%), and all occurred in those receiving serotherapy-containing pre-HCT conditioning (50% of HCTs). Seven DLIs resulted in complete response (18.4%), with 5 of these given after HCTs using serotherapy-containing conditioning. Excluding infectious indications, complete response to DLIs given after transplants with versus without serotherapy-containing pre-HCT conditioning were 30% and 4.3%, respectively. Two patients received DLI for infection and experienced complete resolution without GVHD or CRS, although the efficacy cannot be definitively attributable to the DLI. DLIs given to PTCy-treated patients had low toxicity but limited efficacy, although pre-HCT serotherapy may modulate both toxicity and response. Novel strategies are needed to enhance the therapeutic efficacy of post-transplant cellular therapies without aggravating GVHD.

Prevalence of anti-lymphocyte IgM autoantibodies driving complement activation in COVID-19 patients.

Introduction: COVID-19 patients can develop autoantibodies against a variety of secreted and membrane proteins, including some expressed on lymphocytes. However, it is unclear what proportion of patients might develop anti-lymphocyte antibodies (ALAb) and what functional relevance they might have. Methods: We evaluated the presence and lytic function of ALAb in the sera of a cohort of 85 COVID-19 patients (68 unvaccinated and 17 vaccinated) assigned to mild (N=63), or moderate/severe disease (N=22) groups. Thirty-seven patients were followed-up after recovery. We also analyzed in vivo complement deposition on COVID-19 patients' lymphocytes and examined its correlation with lymphocyte numbers during acute disease. Results: Compared with healthy donors (HD), patients had an increased prevalence of IgM ALAb, which was significantly higher in moderate/severe disease patients and persisted after recovery. Sera from IgM ALAb+ patients exhibited complement-dependent cytotoxicity (CDC) against HD lymphocytes. Complement protein C3b deposition on patients' CD4 T cells was inversely correlated with CD4 T cell numbers. This correlation was stronger in moderate/severe disease patients. Discussion: IgM ALAb and complement activation against lymphocytes may contribute to the acute lymphopenia observed in COVID-19 patients.

Clonal hematopoiesis in people with advanced HIV and associated inflammatory syndromes.

People with HIV (PWH) have a higher age-adjusted mortality due to chronic immune activation and age-related comorbidities. PWH also have higher rates of clonal hematopoiesis (CH) than age-matched non-HIV cohorts; however, risk factors influencing the development and expansion of CH in PWH remain incompletely explored. We investigated the relationship between CH, immune biomarkers, and HIV-associated risk factors (CD4+ and CD8+ T cells, nadir CD4+ count, opportunistic infections [OIs], and immune reconstitution inflammatory syndrome [IRIS]) in a diverse cohort of 197 PWH with median age of 42 years, using a 56-gene panel. Seventy-nine percent had a CD4+ nadir below 200 cells/µL, 58.9% had prior OIs, and 34.5% had a history of IRIS. The prevalence of CH was high (27.4%), even in younger individuals, and CD8+ T cells and nadir CD4+ counts strongly associated with CH after controlling for age. A history of IRIS was associated with CH in a subgroup analysis of patients 35 years of age and older. Inflammatory biomarkers were higher in CH carriers compared with noncarriers, supporting a dysregulated immune state. These findings suggest PWH with low nadir CD4+ and/or inflammatory complications may be at high risk of CH regardless of age and represent a high-risk group that could benefit from risk reduction and potentially targeted immunomodulation.

Helper T cell immunity in humans with inherited CD4 deficiency.

CD4+ T cells are vital for host defense and immune regulation. However, the fundamental role of CD4 itself remains enigmatic. We report seven patients aged 5-61 years from five families of four ancestries with autosomal recessive CD4 deficiency and a range of infections, including recalcitrant warts and Whipple's disease. All patients are homozygous for rare deleterious CD4 variants impacting expression of the canonical CD4 isoform. A shorter expressed isoform that interacts with LCK, but not HLA class II, is affected by only one variant. All patients lack CD4+ T cells and have increased numbers of TCRαß+CD4-CD8- T cells, which phenotypically and transcriptionally resemble conventional Th cells. Finally, patient CD4-CD8- αß T cells exhibit intact responses to HLA class II-restricted antigens and promote B cell differentiation in vitro. Thus, compensatory development of Th cells enables patients with inherited CD4 deficiency to acquire effective cellular and humoral immunity against an unexpectedly large range of pathogens. Nevertheless, CD4 is indispensable for protective immunity against at least human papillomaviruses and Trophyrema whipplei.

Immune responses to SARS-CoV-2 mRNA vaccination in people with idiopathic CD4 lymphopenia.

BACKGROUND: The immunogenicity of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) mRNA vaccines is variable in individuals with different inborn errors of immunity or acquired immune deficiencies and is yet unknown in people with idiopathic CD4 lymphopenia (ICL). OBJECTIVE: We sought to determine the immunogenicity of mRNA vaccines in patients with ICL with a broad range of CD4 T-cell counts. METHODS: Samples were collected from 25 patients with ICL and 23 age- and sex-matched healthy volunteers (HVs) after their second or third SARS-CoV-2 mRNA vaccine dose. Anti-spike and anti-receptor binding domain antibodies were measured. T-cell receptor sequencing and stimulation assays were performed to quantify SARS-CoV-2-specific T-cell responses. RESULTS: The median age of ICL participants was 51 years, and their median CD4 count was 150 cells/µL; 11 participants had CD4 counts ≤100 cells/µL. Anti-spike IgG antibody levels were greater in HVs than in patients with ICL after 2 and 3 doses of mRNA vaccine. There was no detectable significant difference, however, in anti-S IgG between HVs and participants with ICL and CD4 counts >100 cells/µL. The depth of spike-specific T-cell responses by T-cell receptor sequencing was lower in individuals with ICL. Activation-induced markers and cytokine production of spike-specific CD4 T cells in participants with ICL did not differ significantly compared with HVs after 2 or 3 vaccine doses. CONCLUSIONS: Patients with ICL and CD4 counts >100 cells/µL can mount vigorous humoral and cellular immune responses to SARS-CoV-2 vaccination; however, patients with more severe CD4 lymphopenia have blunted vaccine-induced immunity and may require additional vaccine doses and other risk mitigation strategies.

Perturbations of the T-cell receptor repertoire in response to SARS-CoV-2 in immunocompetent and immunocompromised individuals.

BACKGROUND: Functional T-cell responses are essential for virus clearance and long-term protection after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, whereas certain clinical factors, such as older age and immunocompromise, are associated with worse outcome. OBJECTIVE: We sought to study the breadth and magnitude of T-cell responses in patients with coronavirus disease 2019 (COVID-19) and in individuals with inborn errors of immunity (IEIs) who had received COVID-19 mRNA vaccine. METHODS: Using high-throughput sequencing and bioinformatics tools to characterize the T-cell receptor ß repertoire signatures in 540 individuals after SARS-CoV-2 infection, 31 IEI recipients of COVID-19 mRNA vaccine, and healthy controls, we quantified HLA class I- and class II-restricted SARS-CoV-2-specific responses and also identified several HLA allele-clonotype motif associations in patients with COVID-19, including a subcohort of anti-type 1 interferon (IFN-1)-positive patients. RESULTS: Our analysis revealed that elderly patients with COVID-19 with critical disease manifested lower SARS-CoV-2 T-cell clonotype diversity as well as T-cell responses with reduced magnitude, whereas the SARS-CoV-2-specific clonotypes targeted a broad range of HLA class I- and class II-restricted epitopes across the viral proteome. The presence of anti-IFN-I antibodies was associated with certain HLA alleles. Finally, COVID-19 mRNA immunization induced an increase in the breadth of SARS-CoV-2-specific clonotypes in patients with IEIs, including those who had failed to seroconvert. CONCLUSIONS: Elderly individuals have impaired capacity to develop broad and sustained T-cell responses after SARS-CoV-2 infection. Genetic factors may play a role in the production of anti-IFN-1 antibodies. COVID-19 mRNA vaccines are effective in inducing T-cell responses in patients with IEIs.

Long-term Outcomes of Patients With HIV and Pneumocystis jirovecii Pneumonia in the Antiretroviral Therapy Era.

Background: Pneumocystis jirovecii pneumonia (PCP) is one of the most frequent opportunistic infections in people with HIV (PWH). However, there are limited data on long-term outcomes of PCP in the antiretroviral therapy (ART) era. Methods: We conducted a secondary analysis of 2 prospective studies on 307 PWH, 81 with prior PCP, with a median follow-up of 96 weeks. Laboratory data were measured at protocol-defined intervals. We reviewed clinically indicated chest computerized tomography imaging in 63 patients with prior PCP at a median of 58 weeks after PCP diagnosis and pulmonary function tests (PFTs) of patients with (n = 10) and without (n = 14) prior PCP at a median of 18 weeks after ART initiation. Results: After 96 weeks of ART, PWH with prior PCP showed no significant differences in laboratory measurements, including CD4 count, when compared with those without prior PCP. Survival rates following ART initiation were similar. However, PWH with prior PCP had increased evidence of restrictive lung pathology and diffusion impairment in PFTs. Furthermore, on chest imaging, 13% of patients had bronchiectasis and 11% had subpleural cysts. Treatment with corticosteroids was associated with an increased incidence of cytomegalovirus disease (odds ratio, 2.62; P = .014). Conclusions: PCP remains an important opportunistic infection in the ART era. While it did not negatively affect CD4 reconstitution, it could pose an increased risk for incident cytomegalovirus disease with corticosteroid treatment and may cause residual pulmonary sequelae. These findings suggest that PCP and its treatment may contribute to long-term morbidity in PWH, even in the ART era.

An open label randomized controlled trial of atorvastatin versus aspirin in elite controllers and antiretroviral-treated people with HIV.

BACKGROUND: Residual inflammation in people with HIV (PWH) despite suppression of HIV replication is associated with many comorbidities including cardiovascular disease. Targeting inflammation may decrease the risk of cardiovascular disease. METHODS: An open label randomized study was conducted to evaluate the effect of nine months of 81 mg aspirin versus 40 mg atorvastatin in antiretroviral therapy (ART) treated PWH and elite controllers (EC), not on ART. Biomarkers associated with inflammation and virologic indices were measured and analyzed using nonparametric and linear mixed effect models. RESULTS: Fifty-three participants were randomized and 44 were included in the final analysis. Median age was 54 years, 72% were male, 59% were Black. Median CD4 + count was 595 cells/µl in the aspirin and 717 cells/µl in the atorvastatin arm. After 9 months of treatment, plasma soluble (s) CD14 + was reduced in the aspirin group within both treated PWH and EC ( P  = 0.0229), yet only within treated PWH in the atorvastatin group ( P  = 0.0128). A 2.3% reduction from baseline in tissue factor levels was also observed in the aspirin arm, driven by the EC group. In the atorvastatin arm, there was a 4.3% reduction in interleukin-8 levels ( P  = 0.02) and a small decrease of activated CD4 + T cells ( P  < 0.001). No statistically significant differences were observed in the plasma HIV viral load and cell-associated (CA) HIV DNA and RNA. CONCLUSIONS: Aspirin and atorvastatin could play a role in targeting HIV-associated inflammation. Elite controllers may warrant special consideration for anti-inflammatory strategies.

Lack of Evidence for a Role of ACE-2 Polymorphisms as a Bedside Clinical Prognostic Marker of COVID-19.

The novel SARS-CoV-2 coronavirus causes a severe respiratory syndrome referred to as coronavirus disease (COVID-19). The angiotensin-converting enzyme 2 (ACE-2) plays an important role as a cellular receptor for SARS-CoV-2 and is largely expressed in lungs, kidneys, heart and the gastrointestinal tract along with being shed in plasma. The ACE-2 gene and protein show a high level of genetic polymorphism, including simple nucleotide variation, transcriptional variation, post-transcriptional changes, and putative protein mutations that could interfere with the binding or entry of SARS-CoV-2 and affect tissue damage in lungs or other organs. Genetic polymorphisms can impact SARS-CoV-2 viral entry and COVID-19 severity. This single-center study evaluated the possible role of the main ACE-2 polymorphisms (rs143936283, rs2285666, rs41303171, rs35803318, and rs2106809) as potential prognostic markers in SARS-CoV-2-infected individuals. Frozen whole blood was used for DNA isolation and genomic DNA samples were sheared using the Covaris LE220 Focused-ultrasonicator for targeting a peak size of 410 bp. Whole-genome sequencing libraries were generated from fragmented DNA using the Illumina TruSeq DNA PCR-Free HT Library Preparation Kit and sequenced on an Illumina NovaSeq 6000. We did not identify any correlation between ACE-2 polymorphisms and COVID-19 prognosis, suggesting that the interpretation and clinical use of ACE-2 genetic polymorphisms in real-world clinical settings requires further experimental and clinical validation.

Immune reconstitution inflammatory syndrome drives emergence of HIV drug resistance from multiple anatomic compartments in a person living with HIV.

Reservoirs of HIV maintained in anatomic compartments during antiretroviral therapy prevent HIV eradication. However, mechanisms driving their persistence and interventions to control them remain elusive. Here we report the presence of an inducible HIV reservoir within antigen-specific CD4+T cells in the central nervous system of a 59-year-old male with progressive multifocal leukoencephalopathy immune reconstitution inflammatory syndrome (PML-IRIS). HIV production during PML-IRIS was suppressed by modulating inflammation with corticosteroids; selection of HIV drug resistance caused subsequent breakthrough viremia. Therefore, inflammation can influence the composition, distribution and induction of HIV reservoirs, warranting it as a key consideration for developing effective HIV remission strategies.

Reappraisal of Idiopathic CD4 Lymphocytopenia at 30 Years.

BACKGROUND: Idiopathic CD4 lymphocytopenia (ICL) is a clinical syndrome that is defined by CD4 lymphopenia of less than 300 cells per cubic millimeter in the absence of any primary or acquired cause of immunodeficiency. Some 30 years after its original identification, ICL has remained a disease of obscure cause, with limited evidence with respect to its prognosis or management, despite diagnostic and therapeutic innovations. METHODS: We evaluated the clinical, genetic, immunologic, and prognostic characteristics of 108 patients who were enrolled during an 11-year period. We performed whole-exome and targeted gene sequencing to identify genetic causes of lymphopenia. We also performed longitudinal linear mixed-model analyses of T-cell count trajectories and evaluated predictors of clinical events, the response to immunization against coronavirus disease 2019 (Covid-19), and mortality. RESULTS: After the exclusion of patients with genetic and acquired causes of CD4 lymphopenia, the study population included 91 patients with ICL during 374 person-years of follow-up. The median CD4+ T-cell count among the patients was 80 cells per cubic millimeter. The most prevalent opportunistic infections were diseases related to human papillomavirus (in 29%), cryptococcosis (in 24%), molluscum contagiosum (in 9%), and nontuberculous mycobacterial diseases (in 5%). A reduced CD4 count (<100 cells per cubic millimeter), as compared with a CD4 count of 101 to 300 cells, was associated with a higher risk of opportunistic infection (odds ratio, 5.3; 95% confidence interval [CI], 2.8 to 10.7) and invasive cancer (odds ratio, 2.1; 95% CI, 1.1 to 4.3) and a lower risk of autoimmunity (odds ratio, 0.5; 95% CI, 0.2 to 0.9). The risk of death was similar to that in the age- and sex-adjusted general population, but the prevalence of cancer was higher. CONCLUSIONS: Among the study patients, ICL continued to be associated with increased susceptibility to viral, encapsulated fungal, and mycobacterial diseases, as well as with a reduced response to novel antigens and an increased risk of cancer. (Funded by the National Institute of Allergy and Infectious Diseases and the National Cancer Institute; ClinicalTrials.gov number, NCT00867269.).

Mycobacterial Immune Reconstitution Inflammatory Syndrome in HIV is Associated With Protein-Altering Variants in Hemophagocytic Lymphohistiocytosis-Related Genes.

People with HIV (PWH) and mycobacterial infections can develop immune reconstitution inflammatory syndrome (IRIS) after starting antiretroviral therapy. The pathophysiology of mycobacterial-IRIS overlaps with primary hemophagocytic lymphohistiocytosis (pHLH). To assess possible genetic predisposition to IRIS, protein-altering variants in genes associated with HLH were evaluated in 82 PWH and mycobacterial infections who developed IRIS (n = 56) or did not develop IRIS (n = 26). Protein-altering variants in cytotoxicity genes were found in 23.2% of IRIS patients compared to only 3.8% of those without IRIS. These findings suggest a possible genetic component in the risk of mycobacterial IRIS in PWH. Clinical Trials Registration. NCT00286767, NCT02147405.

Severe Mycobacterial Immune Reconstitution Inflammatory Syndrome (IRIS) in Advanced Human Immunodeficiency Virus (HIV) Has Features of Hemophagocytic Lymphohistiocytosis and Requires Prolonged Immune Suppression.

BACKGROUND: People with HIV and mycobacterial infections can develop immune reconstitution inflammatory syndrome (IRIS) after starting antiretroviral therapy (ART). Severe mycobacterial IRIS has an overlapping clinical phenotype with hemophagocytic lymphohistiocytosis (HLH). We evaluated the pathophysiologic similarities between mycobacterial IRIS and HLH to identify clinical and immune predictors of mycobacterial IRIS severity. METHODS: HLH criteria were applied to a longitudinal cohort of 80 patients with HIV (CD4 <100 cells/µL) and mycobacterial infections. Participants were subdivided into IRIS meeting HLH criteria (HLH-IRIS), IRIS without HLH (IRIS), and those without IRIS (non-IRIS). Clinical outcomes were evaluated by regression analyses. Soluble biomarkers and T-cell subsets were assessed at baseline and IRIS-equivalent time points. RESULTS: HLH-IRIS patients required corticosteroids more frequently (OR: 21.5; 95%CI: 5.6-114.8) and for longer duration (21.2; 95%CI: 10.7-31.7 weeks) than those not meeting HLH criteria. Utilizing decision tree analyses, hemoglobin <9.2 g/dL was the best predictor of HLH-IRIS before ART, whereas ferritin, CXCL9 and sCD25 were most diagnostic for HLH at IRIS onset. At the IRIS timepoint, but not baseline, HLH-IRIS patients had lower regulatory and higher activated T cells along with greater production of IFNγ-IL-18 axis biomarkers compared with both IRIS and non-IRIS groups. Principal component analysis corroborated the distinct clustering of HLH-IRIS patients. CONCLUSIONS: Severe mycobacterial IRIS and HLH have an overlapping pathogenesis involving IFNγ and unopposed T-cell activation causing severe inflammatory disease clinically distinguished by hyperferritinemia (hyperferritinemic IRIS [FIRIS]). Hemoglobin, ferritin, CXCL9, and sCD25 identify high-risk patients and may improve risk stratification and therapeutic strategies for mycobacterial IRIS.

Clinical, Virologic, and Immunologic Evaluation of Symptomatic Coronavirus Disease 2019 Rebound Following Nirmatrelvir/Ritonavir Treatment.

BACKGROUND: Nirmatrelvir/ritonavir, the first severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) protease inhibitor, reduces the risk of hospitalization and death by coronavirus disease 2019 (COVID-19) but has been associated with symptomatic rebound after therapy completion. METHODS: Six individuals with relapse of COVID-19 symptoms after treatment with nirmatrelvir/ritonavir, 2 individuals with rebound symptoms without prior antiviral therapy and 7 patients with acute Omicron infection (controls) were studied. Soluble biomarkers and serum SARS-CoV-2 nucleocapsid protein were measured. Nasal swabs positive for SARS-CoV-2 underwent viral isolation and targeted viral sequencing. SARS-CoV-2 anti-spike, anti-receptor-binding domain, and anti-nucleocapsid antibodies were measured. Surrogate viral neutralization tests against wild-type and Omicron spike protein, as well as T-cell stimulation assays, were performed. RESULTS: High levels of SARS-CoV-2 anti-spike immunoglobulin G (IgG) antibodies were found in all participants. Anti-nucleocapsid IgG and Omicron-specific neutralizing antibodies increased in patients with rebound. Robust SARS-CoV-2-specific T-cell responses were observed, higher in rebound compared with early acute COVID-19 patients. Inflammatory markers mostly decreased during rebound. Two patients sampled longitudinally demonstrated an increase in activated cytokine-producing CD4+ T cells against viral proteins. No characteristic resistance mutations were identified. SARS-CoV-2 was isolated by culture from 1 of 8 rebound patients; Polybrene addition increased this to 5 of 8. CONCLUSIONS: Nirmatrelvir/ritonavir treatment does not impede adaptive immune responses to SARS-CoV-2. Clinical rebound corresponds to development of a robust antibody and T-cell immune response, arguing against a high risk of disease progression. The presence of infectious virus supports the need for isolation and assessment of longer treatment courses. CLINICAL TRIALS REGISTRATION: NCT04401436.

Serological responses to human virome define clinical outcomes of Italian patients infected with SARS-CoV-2.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for the pandemic respiratory infectious disease COVID-19. However, clinical manifestations and outcomes differ significantly among COVID-19 patients, ranging from asymptomatic to extremely severe, and it remains unclear what drives these disparities. Here, we studied 159 sequentially enrolled hospitalized patients with COVID-19-associated pneumonia from Brescia, Italy using the VirScan phage-display method to characterize circulating antibodies binding to 96,179 viral peptides encoded by 1,276 strains of human viruses. SARS-CoV-2 infection was associated with a marked increase in immune antibody repertoires against many known pathogenic and non-pathogenic human viruses. This antiviral antibody response was linked to longitudinal trajectories of disease severity and was further confirmed in additional 125 COVID-19 patients from the same geographical region in Northern Italy. By applying a machine-learning-based strategy, a viral exposure signature predictive of COVID-19-related disease severity linked to patient survival was developed and validated. These results provide a basis for understanding the role of memory B-cell repertoire to viral epitopes in COVID-19-related symptoms and suggest that a unique anti-viral antibody repertoire signature may be useful to define COVID-19 clinical severity.

Impact of Innate Immunity, Endothelial Damage, and Metabolic Biomarkers on COVID-19 Severity and Mortality.

In this study, abnormal levels of myeloid activation, endothelial damage, and innate immune markers were associated with severe coronavirus disease 2019 (COVID-19), while higher levels of metabolic biomarkers (irisin, leptin) demonstrated a protective effect. These data support a model for COVID-19 immunopathogenesis linking robust inflammation and endothelial damage in metabolically predisposed individuals.

COVID-19 redux: clinical, virologic, and immunologic evaluation of clinical rebound after nirmatrelvir/ritonavir.

Clinical rebound of COVID-19 after nirmatrelvir/ritonavir treatment has been reported. We performed clinical, virologic, and immune measurements in seven patients with symptomatic rebound, six after nirmatrelvir/ritonavir treatment and one without previous treatment. There was no evidence of severe disease or impaired antibody and T-cell responses in people with rebound symptoms.