Lower seroprevalence for SARS-CoV-2-specific antibodies among kidney transplant recipients compared to the general population in the city of Sao Paulo, Brazil.

BACKGROUND: Kidney transplant recipients have higher COVID-19 associated mortality compared to the general population. However, as only symptomatic patients seek medical attention, the current level of exposure, the main sources of acquisition, and the behavior of humoral immunity over time are poorly understood. METHODS: This cross-sectional prospective single-center study recruited kidney transplant recipients of any age living in Sao Paulo. A sample size of 401 patients was calculated considering the 17.2% seroprevalence in the municipality population from a published survey, a 95% confidence interval and an absolute error of 2%. RESULTS: Of the 2636 eligible patients, 416 were included. The seroprevalence for IgG anti-SARS-CoV-2 was 8.2%. Seroconversion rate decreased with increasing age, from 15.7% (18-35 years) to 8.3% (36-60 years) and 4.2% (>60 years, p = 0.042). Seropositivity among previously confirmed COVID-19 patients was 68.4%, followed by 9.4% in those with flu-like symptoms and only 4.6% among asymptomatic patients (p < 0.0001). Seroprevalence was significantly higher among patients reporting household contact (p = 0.018). Twenty-seven from the 34 IgG+ patients had a second test after 59 (IQR 50-63) days, and, in 33%, the IgG index became below the positivity threshold. CONCLUSIONS: In this cohort of kidney transplant recipients, the seroprevalence for IgG anti-SARS-CoV-2 was lower than that of the general population, decreased with ageing, and was associated with household contacts. In a considerable proportion of the patients, there was a significant decay in the IgG levels in a short period of time. Therefore, preventive strategies, such as prioritization for vaccination, should be urgently considered.

Low Rates of Poliovirus Antibodies in Primary Immunodeficiency Patients on Regular Intravenous Immunoglobulin Treatment.

PURPOSE: Poliovirus has been nearly eliminated as part of a world-wide effort to immunize and contain circulating wild-type polio. Nevertheless, poliovirus has been detected in water supplies and represents a threat to patients with humoral immunodeficiencies where infection can be fatal. To define the risk, we analyzed antibodies to poliovirus 1, 2, and 3 in serum samples collected over a year from patients with primary immunodeficiency diseases (PID) on regular intravenous immunoglobulin (IVIG) replacement. METHODS: Twenty-one patients on regular IVIG replacement therapy were evaluated: Twelve patients with common variable immune deficiency (CVID), six with X-linked agammaglobulinemia (XLA), and three with hyper IgM syndrome (HIGM). Over 1 year, four blood samples were collected from each of these patients immediately before immunoglobulin infusion. One sample of IVIG administered to each patient in the month before blood collection was also evaluated. Poliovirus antibodies were quantified by seroneutralization assay. RESULTS: All IVIG samples had detectable antibodies to the three poliovirus serotypes. Despite that, only 52.4, 61.9, and 19.0% of patients showed protective antibody titers for poliovirus 1, 2, and 3, respectively. Only two patients (9.5%) had protective antibodies for the three poliovirus serotypes on all samples. Most patients were therefore susceptible to all three poliovirus serotypes. CONCLUSIONS: This study demonstrates the need for ongoing vigilance regarding exposure of patients with PID to poliovirus in the community.

Adherence and immune response to revaccination following hematopoietic stem cell transplantation at a pediatric onco-hematology reference center.

BACKGROUND: Revaccination after hematopoietic stem cell transplantation (HSCT) is necessary to compensate for the loss of immunological memory. The aims of this study were to evaluate the adherence to revaccination schedule and the humoral immune response to different vaccine antigens in HSCT pediatric and young adult patients. METHODS: Patients submitted to HSCT for over 3 years were recruited. After written informed consent, a questionnaire was filled in, the vaccination card was analyzed, a blood sample was collected and tested by ELISA for diphtheria, Haemophilus influenzae type b (Hib), hepatitis A, hepatitis B, tetanus, measles, rubella, and varicella antibodies. RESULTS: Sixty-three patients (mean age at HSCT, 10.7 years) were evaluated. Forty-one (65%) were male; 34 (54%) had allogeneic and 29 (46%), autologous HSCT. Complete adherence to diphtheria revaccination was found in 79.4% patients and seropositivity was found in 92% of those who completed the revaccination schedule; for Hib, 68.3% adherence and 95.3% seropositivity were observed; for hepatitis A, 63.5% adherence and 92.5% seropositivity; for 3 doses of hepatitis B, 86.8% adherence and 79.2% seropositivity; for tetanus, 79.4% adherence and 100% seropositivity; for measles and rubella, 17.5% adherence and 100% seropositivity; for varicella, 7.9% adherence and 100% seropositivity. The existence of a Vaccination Center for Special Immunobiologicals in patients' municipality was positively associated with completed vaccine schedule; on the other hand, chronic GVHD was negatively associated with revaccination adherence. CONCLUSION: Hematopoietic stem cell transplantation patients showed good seropositivity rates after complete vaccination schedule. However, a low coverage rate was observed for live attenuated antigens.

High prevalence of hepatitis E virus antibodies among blood donors in Southern Brazil.

Brazil has been classified as moderately endemic for hepatitis E virus (HEV) infection. However, data on the seroprevalence of HEV in this region are limited. This study evaluated the prevalence of past or present HEV infection among blood donors in the metropolitan area of Itajai Valley, Southern Brazil, a region of predominant German heritage, where cultural habits result in a high consumption of pork. Serum samples from 300 blood donors were tested in December 2014 using serological and molecular methods. Anti-HEV IgG antibodies were detected in 30 (10%) subjects, and categorized age groups revealed an age-dependent increase of HEV seroprevalence. Only one subject had anti-HEV IgM, whereas none tested positive for HEV-RNA. The present data demonstrate a higher seroprevalence of anti-HEV IgG in blood donors than previously reported in Brazil.

Serum lipidomic profiling as a useful tool for screening potential biomarkers of hepatitis B-related hepatocellular carcinoma by ultraperformance liquid chromatography-mass spectrometry.

BACKGROUND: Chronic hepatitis B (CHB) virus infection is a major cause of hepatocellular carcinoma (HCC), as late diagnosis is the main factor for the poor survival of patients. There is an urgent need for accurate biomarkers for early diagnosis of HCC. The aim of the study was to explore the serum lipidome profiles of hepatitis B-related HCC to identify potential diagnostic biomarkers. METHODS: An ultraperformance liquid chromatography mass spectrometry (UPLC-MS) lipidomic method was used to characterize serum profiles from HCC (n = 32), liver cirrhosis (LC) (n = 30), CHB (n = 25), and healthy subjects (n = 34). Patients were diagnosed by clinical laboratory and imaging evidence and all presented with CHB while healthy controls had normal liver function and no infectious diseases. RESULTS: The UPLC-MS-based serum lipidomic profile provided more accurate diagnosis for LC patients than conventional alpha-fetoprotein (AFP) detection. HCC patients were discriminated from LC with 78 % sensitivity and 64 % specificity. In comparison, AFP showed sensitivity and specificity of 38 % and 93 %, respectively. HCC was differentiated from CHB with 100 % sensitivity and specificity using the UPLC-MS approach. Identified lipids comprised glycerophosphocolines, glycerophosphoserines and glycerophosphoinositols. CONCLUSIONS: UPLC-MS lipid profiling proved to be an efficient and convenient tool for diagnosis and screening of HCC in a high-risk population.

Helicobacter pylori infection & immune thrombocytopenic purpura in children and adolescents: A randomized controlled trial.

Helicobacter pylori and immune thrombocytopenic purpura (ITP) association is not well established in chronic ITP (cITP) in children, although the cure of thrombocytopenia in approximately half of H. pylori eradicated adult patients has been described. The aim of this study was to investigate the effect of H. pylori eradication on platelet (PLT) recovery in cITP children and adolescents through a randomized, controlled trial. A total of 85 children (mean age 11.4 years) with cITP were prospectively enrolled. Diagnosis of H. pylori was established by two locally validated tests, (13)C-urea breath test and monoclonal stool antigen test. Twenty-two infected patients were identified, and randomly allocated into two groups: H. pylori treatment group (n = 11) and the non-intervention control group (n = 11). The control group was offered treatment if the thrombocytopenia persisted after the follow-up. At baseline, there were no differences regarding age, sex, duration of disease, and PLT count between groups. Sixty three of 85 patients were uninfected. PLT response was classified as complete response: PLT > 150 × 10(9 )l(-1); partial response: PLT 50-150 × 10(9 )l(-1), or an increase of 20-30 × 10(9 )l(-1); no response: PLT < 50 × 10(9 )l(-1) or an increase of <20 × 10(9 )l(-1) after at least 6 months of follow-up. Complete response was observed in 60.0% (6/10, one excluded) H. pylori eradicated patients vs. 18.2% (2/11) in non-eradicated patients (p = 0.08; OR = 6.75) after 6-9 months of follow-up. Among uninfected patients, only 13.8% (8/58) presented complete response. Two non-treated controls were treated after 6-12 months of follow-up, and PLT response was observed in 61.5% (8/13) of H. pylori eradicated patients, and in 19.0% (11/58) of uninfected patients (p = 0.004). Cytotoxin associated gene A and vacuolating cytotoxin gene A IgG antibodies were present in almost all infected patients. Therefore, the study suggests that H. pylori eradication plays a role in the management of H. pylori infected cITP children and adolescents.

Detection of influenza B lineages from 2001 to 2013 in a tertiary hospital in the city of São Paulo, Brazil.

Two antigenically distinct lineages of influenza B viruses, the Victoria-like and Yamagata-like strains, currently circulate among humans. Surveillance from United States of America and Europe over the last 10 years showed that the chance of a correct matching between vaccine and the circulating lineage had been 50%. We investigated influenza B infection in different patient groups (asymptomatic, general community, with comorbidities and hospitalised) attended at a tertiary hospital in the city of São Paulo, Brazil between 2001-2013. All samples were screened for influenza B virus by one-step real-time reverse transcription-polymerase chain reaction. From 2,992 respiratory samples collected, 114 (3.8%) tested positive for influenza B. Teenagers (13-18 years) presented the highest rate of 18.5% (odds ratio 22.87, 95% confidence interval 2.90-180.66, p < 0.001). One hundred nine samples could be characterised: 50 were Yamagata-like and 59 were Victoria-like strains. Mismatching between the vaccine and predominant circulating strain was observed in 2002 and 2013 seasons. Based on data collected during a period of 12 years, we found that influenza B was more frequent in teenagers. Co-circulation of both lineages and mismatch with the vaccine strain can occur. Our data highlighted the importance of quadrivalent vaccines and future analysis of the age groups included in vaccination programs.

Viral aetiology of common colds of outpatient children at primary care level and the use of antibiotics.

Although antibiotics are ineffective against viral respiratory infections, studies have shown high rates of prescriptions worldwide. We conducted a study in Brazil to determine the viral aetiologies of common colds in children and to describe the use of antibiotics for these patients. Children up to 12 years with common colds were enrolled from March 2008-February 2009 at a primary care level facility and followed by regular telephone calls and medical consultations. A nasopharyngeal wash was obtained at enrollment and studied by direct fluorescence assay and polymerase chain reaction for nine different types of virus. A sample of 134 patients was obtained, median age 2.9 years (0.1-11.2 y). Respiratory viruses were detected in 73.9% (99/134) with a coinfection rate of 30.3% (30/99). Rhinovirus was the most frequent virus (53/134; 39.6%), followed by influenza (33/134; 24.6%) and respiratory syncytial virus (8/134; 13.4%). Antibiotic prescription rate was 39.6% (53/134) and 69.8% (37/53) were considered inappropriate. Patients with influenza infection received antibiotics inappropriately in a greater proportion of cases when compared to respiratory syncytial virus and rhinovirus infections (p = 0.016). The rate of inappropriate use of antibiotics was very high and patients with influenza virus infection were prescribed antibiotics inappropriately in a greater proportion of cases.

Optimisation of a quantitative polymerase chain reaction-based strategy for the detection and quantification of human herpesvirus 6 DNA in patients undergoing allogeneic haematopoietic stem cell transplantation.

Human herpesvirus 6 (HHV-6) may cause severe complications after haematopoietic stem cell transplantation (HSCT). Monitoring this virus and providing precise, rapid and early diagnosis of related clinical diseases, constitute essential measures to improve outcomes. A prospective survey on the incidence and clinical features of HHV-6 infections after HSCT has not yet been conducted in Brazilian patients and the impact of this infection on HSCT outcome remains unclear. A rapid test based on real-time quantitative polymerase chain reaction (qPCR) has been optimised to screen and quantify clinical samples for HHV-6. The detection step was based on reaction with TaqMan® hydrolysis probes. A set of previously described primers and probes have been tested to evaluate efficiency, sensitivity and reproducibility. The target efficiency range was 91.4% with linearity ranging from 10-106 copies/reaction and a limit of detection of five copies/reaction or 250 copies/mL of plasma. The qPCR assay developed in the present study was simple, rapid and sensitive, allowing the detection of a wide range of HHV-6 loads. In conclusion, this test may be useful as a practical tool to help elucidate the clinical relevance of HHV-6 infection and reactivation in different scenarios and to determine the need for surveillance.

Chronic hepatitis E virus infection in a pediatric female liver transplant recipient.

We describe a case of chronic hepatitis E virus (HEV) infection in a 13-year-old female liver transplant recipient with recurrent increased aminotransferase levels and acute cellular rejection. This finding demonstrates that chronic HEV infection can occur and should be further investigated in immunocompromised patients in Latin America.

Past and current hepatitis E virus infection in renal transplant patients.

The chronic course of hepatitis E virus infection in immunosuppressed patients has been recently documented; however, clinical features and factors associated with this occurrence are not well known. The aim of this study was to evaluate the prevalence of previous or current HEV infection in renal transplant patients. One hundred ninety-two kidney transplant patients were studied and classified in three groups: G1-infected with hepatitis B and/or C virus; G2-patients with elevated ALT; G3-patients with normal ALT and no hepatotropic virus infection. Demographic, epidemiologic and clinical characteristics were compared between the groups. Patients with HEV infection (previous or current) were also compared to those who tested negative for HEV. HEV infection was detected using serologic (anti-HEV IgG) and molecular (HEV RNA) methods. Anti-HEV IgG was positive in 28 (15%) while HEV RNA was positive in 20 (10%). When both markers were considered, 44 (23%) patients showed evidence of previous or current HEV infection. However, both markers were concomitantly positive in only four cases (2%). In the comparative analysis, patients infected with HBV and/or HCV showed lower frequency of anti-HEV IgG (P = 0.009). There was no difference regarding demographic, epidemiologic and laboratory variable between viremic and non-viremic patients. In conclusion, past and current infection with HEV was a frequent finding among renal transplant recipients. Actively infected patients (HEV RNA positive) did not present distinct demographic and epidemiological characteristics or laboratory alterations suggestive of underlying liver damage. Therefore, infection with HEV can only be detected in immunosuppressed patients by systematic investigation of HEV RNA.

Seroprevalence trends of anti-SARS-CoV-2 antibodies in the adult population of the São Paulo Municipality, Brazil: Results from seven serosurveys from June 2020 to April 2022. The SoroEpi MSP Study.

BACKGROUND: Sequential population-based household serosurveys of SARS-CoV-2 covering the COVID-19 pre- and post-vaccination periods are scarce in Brazil. This study investigated seropositivity trends in the municipality of São Paulo. METHODS: We conducted seven cross-sectional surveys of adult population-representative samples between June 2020 and April 2022. The study design included probabilistic sampling, test for SARS-CoV-2 antibodies using the Roche Elecsys anti-nucleocapsid assay, and statistical adjustments for population demographics and non-response. The weighted seroprevalences with 95% confidence intervals (CI) were estimated by sex, age group, race, schooling, and mean income study strata. Time trends in seropositivity were assessed using the Joinpoint model. We compared infection-induced seroprevalences with COVID-19 reported cases in the pre-vaccination period. RESULTS: The study sample comprised 8,134 adults. The overall SARS-CoV-2 seroprevalence increased from 11.4% (95%CI: 9.2-13.6) in June 2020 to 24.9% (95%CI: 21.0-28.7) in January 2021; from 38.1% (95%CI: 34.3-41.9) in April 2021 to 77.7% (95%CI: 74.4-81.0) in April 2022. The prevalence over time was higher in the subgroup 18-39 years old than in the older groups from Survey 3 onwards. The self-declared Black or mixed (Pardo) group showed a higher prevalence in all surveys compared to the White group. Monthly prevalence rose steeply from January 2021 onwards, particularly among those aged 60 years or older. The infection-to-case ratios ranged from 8.9 in June 2020 to 4.3 in January 2021. CONCLUSIONS: The overall seroprevalence rose significantly over time and with age and race subgroup variations. Increases in the 60 years or older age and the White groups were faster than in younger ages and Black or mixed (Pardo) race groups in the post-vaccination period. Our data may add to the understanding of the complex and changing population dynamics of the SARS-CoV-2 infection, including the impact of vaccination strategies and the modelling of future epidemiological scenarios.

Severe metapneumovirus infections among immunocompetent and immunocompromised patients admitted to hospital with respiratory infection.

Human metapneumovirus (hMPV) is considered an important cause of acute respiratory infections. hMPV can cause morbidity in hematopoietic stem cell transplant recipients and recent research has demonstrated that it is an important virus in patients admitted to hospital with respiratory infections and suspected of having pandemic 2009 influenza A (H1N1pdm09) virus. The purpose of this study was to investigate infections caused by hMPV in two groups of patients admitted to hospital: Immunocompromized patients with a potential risk of severe outcomes and immunocompetent patients with severe acute respiratory syndrome. A total of 288 samples were tested: 165 samples were collected from patients with suspected influenza A (H1N1) pdm09 infection during the first pandemic wave in 2009; and 123 samples were collected from patients of a hematopoietic stem cell transplantation program in 2008-2009. Amplification of the hMPV genes was performed by polymerase chain reaction. This was followed by sequencing and phylogenetic analysis. hMPV was detected in 14.2% (41/288) of all samples: 17% (28/165) of immunocompetent patients with suspected H1N1 infection and 10.6% (13/123) among hematopoietic stem cell transplant recipients. hMPV accounted for 12.1% (8/66) of immunocompetent adults patients with severe respiratory infections (median age, 55.9 years). Two hMPV subtypes were identified, A2 (26.9%; 7/26) and B2 (73.1%; 19/26) but no difference was observed between the patient groups in terms of age or immunosuppression level. This study highlights the significance of hMPV in immunocompetent adult patients with severe infections and further investigations are recommended for understanding the impact of this virus.

First report and molecular characterization of hepatitis E virus infection in renal transplant recipients in Brazil.

Hepatitis E virus (HEV) causes acute and chronic hepatitis in organ transplant recipients. Serological evidence for HEV infection has been discovered in various population groups in Brazil, and a single acute case has been confirmed. To date, however, no cases of HEV infection in immunocompromised patients have been reported in Brazil. This study aimed to identify and characterize hepatitis E cases in renal transplant recipients in Brazil. A retrospective study was performed on 96 serum samples from renal transplant recipients with unexplained liver enzymes elevation. Three confirmed cases of HEV infection were identified that lacked seroconversion to HEV IgG antibodies. The prevalence of HEV in these patients was 3.1%. Using a sequence analysis of a 304-nucleotide fragment within ORF2, the strains were classified as genotype 3 with a low percent identity to previously characterized strains. This is the first report of hepatitis E infection in renal transplant recipients in Brazil, and the data indicate that a novel genotype 3 subvariant may be present and that further investigation is necessary to characterize the circulating HEV strains. In this setting, HEV infection should be considered as a potential cause of abnormal liver tests of unknown origin.

A survey strategy for human respiratory syncytial virus detection among haematopoietic stem cell transplant patients: epidemiological and methodological analysis.

Human respiratory syncytial virus (HRSV) causes severe infections among children and immunocompromised patients. We compared HRSV infections among Haematopoietic Stem Cell Transplant program (HSCT) patients and children using direct immunofluorescence (DFA), point-of-care RSV Bio Easy® and a polymerase chain reaction (PCR) assay. Overall, 102 samples from HSCT patients and 128 from children obtained positivity rate of 18.6% and 14.1% respectively. PCR sensitivity was highest mainly on samples collected after five days of symptoms onset. A combination of both DFA and reverse transcriptase-PCR methods for HSCT high-risk patients is the best diagnostic flow for HRSV diagnosis among these patients.

Human coronavirus ocurrence in different populations of Sao Paulo: A comprehensive nine-year study using a pancoronavirus RT-PCR assay.

Human coronaviruses (HCoVs) are considered one of the most common respiratory viruses associated with respiratory tract illnesses. An emergent human coronavirus was identified as the causal agent of an epidemic of severe acute respiratory syndrome (SARS) during 2002-2003. The severity of the disease combined with its rapid spread requires the continuous surveillance of coronaviruses in worldwide populations. Epidemiological and clinical data of HCoVs infectious in the Brazilian population are scarce and restricted to one or two groups of patients. Our study aimed to investigate retrospectively the presence of HCoVs in different populations of São Paulo presenting acute respiratory tract infections (ARIs) during the years of 2001-2010. A pancoronavirus RT-PCR was performed in this study. Coronaviruses were detected in 126 (11.5%) of 1,087 specimens. Peaks detection frequency was observed during 2002-2004 and 2008-2009, with the highest detection in 2008. The prevalence of HCoVs was higher among children with heart diseases (24.6%), patients under stem cell transplantation program (24.3%) and renal transplanted patients (20.2%). Coryza, cough and fever were the most common symptoms at presentation of positive cases and wheezing, a lower respiratory tract infection symptom was reported by 12% of the total, and 27% of high at-risk patients. HCoVs may have an important role among patients with underlying conditions and transplanted ones.

Infections with human coronaviruses NL63 and OC43 among hospitalised and outpatient individuals in São Paulo, Brazil.

The incidence and clinical features of human coronaviruses (HCoVs) among Brazilian patients with respiratory illness are not well known. We investigated the prevalence of HCoVs among Brazilian outpatients and hospitalised patients with respiratory illnesses during 2009 and 2010. To identify the HCoVs, pancoronavirus and species-specific reverse-transcriptase polymerase chain reaction assays were performed. Five of 394 samples were positive for HCoVs (1.2%): 1/182 (0.5%) outpatients and 4/212 (1.8%) hospitalised patients. The OC43 and NL63 HCoVs were identified. Two patients were admitted to the intensive care unit. Underlying chronic disease was reported in cases and one diabetic adult died. HCoVs can cause lower respiratory infections and hospitalisation. Patients with pre-existing conditions and respiratory infections should be evaluated for HCoV infections.

Seroprevalence of hepatitis E virus infection among volunteer blood donors in Central Brazil.

A cross-sectional study was carried out in the Hematology and Hemotherapy Institute of the state of Mato Grosso do Sul (Hemosul) to evaluate the seroprevalence and risk factors of Hepatitis E Virus (HEV) exposure among volunteer blood donors in Central Brazil. Two-hundred fifty samples from the biorepository were tested for anti-HEV IgG and IgM using the Wantai HEV ELISA test. The seroprevalence of HEV exposure was 6.4% (95% CI: 3.9-10.2). Being born in another state of Brazil, mainly in the Southeast and South regions, was associated with a higher risk of HEV exposure (p < 0.001).

Ocular manifestations of monkeypox: a case report.

Monkeypox disease is a viral zoonosis with symptoms similar to those seen in the past in smallpox (variola), although clinically less severe. Following the eradication of smallpox in 1980 and the subsequent cessation of smallpox vaccination, monkeypox has emerged as the most important orthopoxvirus from a public health standpoint. Monkeypox virus occurs primarily in central and western Africa, often in tropical forests, and has increasingly manifested in urban areas. Animal hosts include various rodents and nonhuman primates. We report the case of a patient with monkeypox disease who developed ocular complaints (eye discomfort and conjunctivitis) and had detectable conjunctival lesions on biomicroscopy and fluorescein testing. Its ophthalmological manifestations are still poorly known.

Prediction of SARS-CoV-2-positivity from million-scale complete blood counts using machine learning.

Background: The Complete Blood Count (CBC) is a commonly used low-cost test that measures white blood cells, red blood cells, and platelets in a person's blood. It is a useful tool to support medical decisions, as intrinsic variations of each analyte bring relevant insights regarding potential diseases. In this study, we aimed at developing machine learning models for COVID-19 diagnosis through CBCs, unlocking the predictive power of non-linear relationships between multiple blood analytes. Methods: We collected 809,254 CBCs and 1,088,385 RT-PCR tests for SARS-Cov-2, of which 21% (234,466) were positive, from 900,220 unique individuals. To properly screen COVID-19, we also collected 120,807 CBCs of 16,940 individuals who tested positive for other respiratory viruses. We proposed an ensemble procedure that combines machine learning models for different respiratory infections and analyzed the results in both the first and second waves of COVID-19 cases in Brazil. Results: We obtain a high-performance AUROC of 90 + % for validations in both scenarios. We show that models built solely of SARS-Cov-2 data are biased, performing poorly in the presence of infections due to other RNA respiratory viruses. Conclusions: We demonstrate the potential of a novel machine learning approach for COVID-19 diagnosis based on a CBC and show that aggregating information about other respiratory diseases was essential to guarantee robustness in the results. Given its versatile nature, low cost, and speed, we believe that our tool can be particularly useful in a variety of scenarios-both during the pandemic and after.