Data-driven, cross-disciplinary collaboration: lessons learned at the largest academic health center in Latin America during the COVID-19 pandemic.

Introduction: The COVID-19 pandemic has prompted global research efforts to reduce infection impact, highlighting the potential of cross-disciplinary collaboration to enhance research quality and efficiency. Methods: At the FMUSP-HC academic health system, we implemented innovative flow management routines for collecting, organizing and analyzing demographic data, COVID-related data and biological materials from over 4,500 patients with confirmed SARS-CoV-2 infection hospitalized from 2020 to 2022. This strategy was mainly planned in three areas: organizing a database with data from the hospitalizations; setting-up a multidisciplinary taskforce to conduct follow-up assessments after discharge; and organizing a biobank. Additionally, a COVID-19 curated collection was created within the institutional digital library of academic papers to map the research output. Results: Over the course of the experience, the possible benefits and challenges of this type of research support approach were identified and discussed, leading to a set of recommended strategies to enhance collaboration within the research institution. Demographic and clinical data from COVID-19 hospitalizations were compiled in a database including adults and a minority of children and adolescents with laboratory confirmed COVID-19, covering 2020-2022, with approximately 350 fields per patient. To date, this database has been used in 16 published studies. Additionally, we assessed 700 adults 6 to 11 months after hospitalization through comprehensive, multidisciplinary in-person evaluations; this database, comprising around 2000 fields per subject, was used in 15 publications. Furthermore, thousands of blood samples collected during the acute phase and follow-up assessments remain stored for future investigations. To date, more than 3,700 aliquots have been used in ongoing research investigating various aspects of COVID-19. Lastly, the mapping of the overall research output revealed that between 2020 and 2022 our academic system produced 1,394 scientific articles on COVID-19. Discussion: Research is a crucial component of an effective epidemic response, and the preparation process should include a well-defined plan for organizing and sharing resources. The initiatives described in the present paper were successful in our aim to foster large-scale research in our institution. Although a single model may not be appropriate for all contexts, cross-disciplinary collaboration and open data sharing should make health research systems more efficient to generate the best evidence.

Evaluation of enterovirus concentration, species identification, and cerebrospinal fluid parameters in patients of different ages with aseptic meningitis in São Paulo, Brazil.

Human enteroviruses (EV) are the most common cause of aseptic meningitis worldwide. Data on EV viral load in cerebrospinal fluid (CSF) and related epidemiological studies are scarce in Brazil. This study investigated the influence of EV viral load on CSF parameters, as well as identifying the involved species. CSF samples were collected in 2018-2019 from 140 individuals at The Hospital das Clínicas, São Paulo. The EV viral load was determined using real-time quantitative polymerase chain reaction, while EV species were identified by 5'UTR region sequencing. Median viral load was 5.72 log10 copies/mL and did not differ by subjects' age and EV species. Pleocytosis was observed in 94.3% of cases, with the highest white blood cell (WBC) counts in younger individuals. Viral load and WBC count were correlated in children (p = 0.0172). Elevated lactate levels were observed in 60% of cases and correlated with the viral load in preteen-teenagers (p = 0.0120) and adults (p = 0.0184). Most individuals had normal total protein levels (70.7%), with higher in preteen-teenagers and adults (p < 0.0001). By sequencing, 8.2% were identified as EV species A and 91.8% as species B. Age-specific variations in CSF characteristics suggest distinct inflammatory responses in each group.

Prevalence and clinical consequences of Hepatitis C virus infection in patients undergoing hematopoietic stem cell transplantation.

Hepatitis C virus (HCV) infection is a significant cause of morbidity and mortality among hematopoietic stem cell transplant (HCT) recipients. In Brazil, its occurrence in HCT recipients remains undetermined. We now report on HCV prevalence in HCT recipients and its clinical consequences. The medical records of all HCT recipients seen at Hospital das Clinicas, Sao Paulo University Medical School, from January 2010 to January 2020 were reviewed to determine HCV serostatus. A retrospective analysis of medical charts was undertaken on all seropositive cases to determine HCV genotype, presence of liver fibrosis, co-infections with other viruses, previous treatments, and clinical evolution of liver pathology after HCT. Of the 1,293 HCT recipients included in the study, seven (0.54%) were HCV antibody-positive and five (0.39%) were also viremic for HCV-RNA. Four of these individuals had moderate to severe liver fibrosis (METAVIR F2/F3) and one was cirrhotic. Two of the viremic patients developed acute liver dysfunction following transplantation. All patients had their acute episode of liver dysfunction resolved with no further complications. Four of the viremic patients were treated for HCV infection with direct acting agents (DAA). Information regarding HCV treatment was lacking for one of the viremic HCV patients due to loss of follow up. Sustained anti-virologic responses were observed in three cases after the use of DAA. The detection of HCV in hematological adults undergoing HCT and its successful treatment with DAA highlight the necessity of testing for HCV both prior to and following transplantation.

Seroprevalence of hepatitis B, C, and D and associated factors in the semi-isolated Yanomami Amazonian indigenous community.

BACKGROUND: Viral hepatitis is a significant health concern among indigenous population in the Americas. In Brazil, reports find high endemicity of HBV and HDV infections has been reported in several indigenous groups. However, few studies have documented the prevalence of HBV, HCV and HDV in the Yanomami. In this study, the prevalence of hepatitis B, C, and D serological markers and potential risk factors were investigated to provide guidance for the development of strategies aimed at reducing viral transmission in the Yanomami indigenous villages. METHODS: This cross-sectional study was carried out in March 2015 and included 430 individuals from four Yanomami villages: Alapusi (n = 78), Castanha/Ahima (n = 126), Gasolina (n = 105), and Taibrapa (n = 121). A rapid test was used for detection of HBsAg and anti-HCV and chemiluminescent immunoassay for anti-HBs, anti-HBc, and anti-HDV antibodies. RESULTS: HBsAg, anti-HBc, and anti-HBs were detected in 8.8, 45.5, and 49.4% of the participants, respectively. The estimated HBV status: current infection 9.6% (38/395); resolved infection 43.3% (171/395); vaccine immunity 20.5% (81/395), and susceptible to HBV 26.6% (105/395). Gasolina presented the lowest prevalence of HBV infection (6.5%) and the highest prevalence of vaccine immunity (26.9%). Children < 15 years old were highly susceptible to infection, as 53.1% did not have antibodies to HBV, while more than 80% of individuals over 45 years of age had been exposed to HBV. The markers for HDV were founded among 12.5% (4/32) of the HBsAg carriers. Anti-HCV was identified in all villages, with the highest prevalence in Alapusi (5.1%). Possible risk factors such as the use of piercings, tattoos, and contact with prospectors showed no statistical difference between the groups. CONCLUSIONS: Viral hepatitis B and serological markers for HCV and HDV were found to be widely distributed among the Yanomami indigenous community, while the prevalence of vaccine immunity to HBV was low. This finding reinforces the importance of promoting systematized diagnostic and vaccination strategies in indigenous communities. Our data confirm that isolated and difficult-to-reach indigenous communities lack appropriate access to diagnosis, treatment, and vaccination.

Prevalence and clinical consequences of Hepatitis C virus infection in patients undergoing hematopoietic stem cell transplantation

ABSTRACT Hepatitis C virus (HCV) infection is a significant cause of morbidity and mortality among hematopoietic stem cell transplant (HCT) recipients. In Brazil, its occurrence in HCT recipients remains undetermined. We now report on HCV prevalence in HCT recipients and its clinical consequences. The medical records of all HCT recipients seen at Hospital das Clinicas, Sao Paulo University Medical School, from January 2010 to January 2020 were reviewed to determine HCV serostatus. A retrospective analysis of medical charts was undertaken on all seropositive cases to determine HCV genotype, presence of liver fibrosis, co-infections with other viruses, previous treatments, and clinical evolution of liver pathology after HCT. Of the 1,293 HCT recipients included in the study, seven (0.54%) were HCV antibody-positive and five (0.39%) were also viremic for HCV-RNA. Four of these individuals had moderate to severe liver fibrosis (METAVIR F2/F3) and one was cirrhotic. Two of the viremic patients developed acute liver dysfunction following transplantation. All patients had their acute episode of liver dysfunction resolved with no further complications. Four of the viremic patients were treated for HCV infection with direct acting agents (DAA). Information regarding HCV treatment was lacking for one of the viremic HCV patients due to loss of follow up. Sustained anti-virologic responses were observed in three cases after the use of DAA. The detection of HCV in hematological adults undergoing HCT and its successful treatment with DAA highlight the necessity of testing for HCV both prior to and following transplantation.

Intranasal Liposomal Formulation of Spike Protein Adjuvanted with CpG Protects and Boosts Heterologous Immunity of hACE2 Transgenic Mice to SARS-CoV-2 Infection.

Mucosal vaccination appears to be suitable to protect against SARS-CoV-2 infection. In this study, we tested an intranasal mucosal vaccine candidate for COVID-19 that consisted of a cationic liposome containing a trimeric SARS-CoV-2 spike protein and CpG-ODNs, a Toll-like receptor 9 agonist, as an adjuvant. In vitro and in vivo experiments indicated the absence of toxicity following the intranasal administration of this vaccine formulation. First, we found that subcutaneous or intranasal vaccination protected hACE-2 transgenic mice from infection with the wild-type (Wuhan) SARS-CoV-2 strain, as shown by weight loss and mortality indicators. However, when compared with subcutaneous administration, the intranasal route was more effective in the pulmonary clearance of the virus and induced higher neutralizing antibodies and anti-S IgA titers. In addition, the intranasal vaccination afforded protection against gamma, delta, and omicron virus variants of concern. Furthermore, the intranasal vaccine formulation was superior to intramuscular vaccination with a recombinant, replication-deficient chimpanzee adenovirus vector encoding the SARS-CoV-2 spike glycoprotein (Oxford/AstraZeneca) in terms of virus lung clearance and production of neutralizing antibodies in serum and bronchial alveolar lavage (BAL). Finally, the intranasal liposomal formulation boosted heterologous immunity induced by previous intramuscular vaccination with the Oxford/AstraZeneca vaccine, which was more robust than homologous immunity.

Association between torquetenovirus in vaginal secretions and infertility: An exploratory metagenomic analysis.

PROBLEM: The association of viruses with infertility remains incompletely evaluated. METHOD OF STUDY: Vaginal secretions from 46 women seeking treatment in the Center for Reproductive Medicine and Infertility at Weill Cornell Medicine were tested for viruses by metagenomic analysis by lab personnel blinded to all clinical data. RESULTS: Torquetenovirus (TTV) was identified in 16 women, alphapapillomavirus in seven women and most were positive for bacteriophages. Twelve of the subjects were fertile and sought to freeze their oocytes for future implantation. These women were all negative for TTV. In contrast, 16 of the 34 women (47.1%) being treated for infertility were TTV-positive (p = .0035). Evaluating the women by cause of infertility, five of nine women (55.6%) whose male partner had inadequate sperm parameters and six of 14 women (42.9%) with defective ovulation were TTV positive (p = .0062 and p = .0171, respectively, vs. the fertile women). Alphapapillomavirus was identified in one (8.3%) fertile woman, five (35.7%) women with ovulation deficiency, and one (11.1%) woman with male factor infertility. These differences were not statistically significant. There were no differences in bacteriophage families or the presence of Lactobacillus phages between fertile or infertile women or between different causes of infertility. There was a negative association between TTV detection and Lactobacillus crispatus dominance in the vaginal microbiota (p = .0184), but no association between TTV detection and the presence of alphapapillomavirus or Candida species. CONCLUSION: Detection of TTV in the vagina might be a biomarker for specific causes of infertility.

Survival analysis over a 20-year period of a Brazilian cohort of blood donors coinfected HIV-HCV.

Among individuals coinfected with HCV and HIV, studies of mortality from non-hepatic causes have shown inconsistent results. The aim of this study was to investigate the contribution of HCV and HIV co-infection to mortality from hepatic and non-hepatic causes in Brazil. This retrospective cohort study included blood donors from Fundação Pró-Sangue de São Paulo (FPS) who were followed from 1994 to 2016 to compare mortality and its causes between HIV-HCV coinfected individuals versus those seronegative for all tested infections. Records from the FPS database and the Mortality Information System were linked through a probabilistic record Relationship (RL). The Hazard Ratio (HR) was estimated using Cox multiple regression models. HCV-HIV coinfected individuals compared to seronegative individuals had a higher risk of death from all causes (HR = 14.54), non-liver neoplasms (HR = 2.55), infections (HR = 10.37) and liver disease (HR = 7.0). In addition, HCV mono-infected individuals compared to seronegative individuals had a higher risk of death from all causes (HR = 2.23), liver cancer (HR = 32.21), liver disease (HR = 14.92), infection (HR = 3.22), and trauma (HR = 1.68). Individuals coinfected with HCV and HIV have increased overall mortality and death due to infections, liver diseases and non-liver neoplasms as compared to those uninfected with HCV and HIV.

Characterization of Torquetenovirus in amniotic fluid at the time of in utero fetal surgery: correlation with early premature delivery and respiratory distress.

Torquetenovirus (TTV) is a commensal virus present in many healthy individuals. Although considered to be non-pathogenic, its presence and titer have been shown to be indicative of altered immune status in individuals with chronic infections or following allogeneic transplantations. We evaluated if TTV was present in amniotic fluid (AF) at the time of in utero surgery to correct a fetal neurological defect, and whether its detection was predictive of adverse post-surgical parameters. AF was collected from 27 women by needle aspiration prior to a uterine incision. TTV titer in the AF was measured by isolation of viral DNA followed by gene amplification and analysis. The TTV genomes were further characterized and sequenced by metagenomics. Pregnancy outcome parameters were subsequently obtained by chart review. Three of the AFs (11.1%) were positive for TTV at 3.36, 4.16, and 4.19 log10 copies/mL. Analysis of their genomes revealed DNA sequences similar to previously identified TTV isolates. Mean gestational age at delivery was >2 weeks earlier (32.5 vs. 34.6 weeks) and the prevalence of respiratory distress was greater (100% vs. 20.8%) in the TTV-positive pregnancies. TTV detection in AF prior to intrauterine surgery may indicate elevated post-surgical risk for earlier delivery and newborn respiratory distress.

Association between development of severe COVID-19 and a polymorphism in the CIAS1 gene that codes for an inflammasome component.

An elevated pro-inflammatory cytokine response is associated with severe life-threatening symptoms in individuals with Coronavirus Disease-2019 (COVID). The inflammasome is an intracellular structure responsible for generation of interleukin (IL)-1ß and IL-18. NALP3, a product of the CIAS1 gene, is the rate-limiting component for inflammasome activity. We evaluated if a CIAS1 42 base pair length polymorphism (rs74163773) was associated with severe COVID. DNA from 93 individuals with severe COVID, 38 with mild COVID, and 98 controls were analyzed for this polymorphism. The 12 unit repeat allele is associated with the highest inflammasome activity. Five alleles, corresponding to 6, 7, 9, 12 or 13 repeat units, divided into 12 genotypes were identified. The frequency of the 12 unit repeat allele was 45.3% in those with severe disease as opposed to 30.0% in those with mild disease and 26.0% in controls (p < 0.0001, severe vs. controls). In contrast, the 7 unit repeat allele frequency was 30.1% in controls as opposed to 14.0% and 12.5% in those with severe or mild disease, respectively (p ≤ 0.0017). We conclude that individuals positive for the CIAS1 12 allele may be at elevated risk for development of severe COVID due to an increased level of induced pro-inflammatory cytokine production.

SARS-CoV-2 Detection and Culture in Different Biological Specimens from Immunocompetent and Immunosuppressed COVID-19 Patients Infected with Two Different Viral Strains.

Introduction-The dynamics of SARS-CoV-2 shedding and replication in humans remain incompletely understood. Methods-We analyzed SARS-CoV-2 shedding from multiple sites in individuals with an acute COVID-19 infection by weekly sampling for five weeks in 98 immunocompetent and 25 immunosuppressed individuals. Samples and culture supernatants were tested via RT-PCR for SARS-CoV-2 to determine viral clearance rates and in vitro replication. Results-A total of 2447 clinical specimens were evaluated, including 557 nasopharyngeal swabs, 527 saliva samples, 464 urine specimens, 437 anal swabs and 462 blood samples. The SARS-CoV-2 genome sequences at each site were classified as belonging to the B.1.128 (ancestral strain) or Gamma lineage. SARS-CoV-2 detection was highest in nasopharyngeal swabs regardless of the virus strain involved or the immune status of infected individuals. The duration of viral shedding varied between clinical specimens and individual patients. Prolonged shedding of potentially infectious virus varied from 10 days up to 191 days, and primarily occurred in immunosuppressed individuals. Virus was isolated in culture from 18 nasal swab or saliva samples collected 10 or more days after onset of disease. Conclusions-Our findings indicate that persistent SARS-CoV-2 shedding may occur in both competent or immunosuppressed individuals, at multiple clinical sites and in a minority of subjects is capable of in vitro replication.

Factors Associated with Spontaneous Clearance of Recently Acquired Hepatitis C Virus among HIV-Positive Men in Brazil.

INTRODUCTION: The objective of the present study was to describe the clinical and epidemiological aspects of recently acquired hepatitis C virus (HCV) infection and the frequency of its spontaneous clearance in a people living with the human immunodeficiency virus (PLWH) cohort. METHODS: We reviewed the medical records from all PLWH at the human immunodeficiency virus (HIV) outpatient reference clinic affiliated with the University of São Paulo, Brazil, and identified, by immunoassays and RNA-PCR individuals who acquired HCV infection between January 2015 and December 2017. The factors associated with subsequent spontaneous clearance of the infection in this group were identified and analyzed. RESULTS: Among 3143 PLWH individuals, 362 (11.5%) were coinfected with HCV. Forty-eight (13.2%) of these subjects first became HCV-positive between January 2015 and December 2017. Spontaneous HCV clearance was documented in 23 individuals (47.9%). The majority of this latter group were male (83.3%), and the median age was 31 years (23-39). The main risk group for HCV acquisition was men who had sex with men (MSM) (89.5%). In a multivariate analysis, only an elevated CD4+ T lymphocyte count at the time of seroconversion was found to be associated with subsequent HCV clearance (p = 0.025). CONCLUSIONS: In HIV-infected individuals in Sao Paulo, Brazil, most cases of recent HCV transmission were by sexual exposure. In PLWH, particularly in MSM, the individual's CD4+ T lymphocyte count is a determinant of whether an acquired HCV infection will be prolonged or will spontaneously clear.

Impact of the COVID-19 Pandemic on Cervical Cancer Screening in São Paulo State, Brazil.

INTRODUCTION: The early identification of precursor lesions followed by appropriate treatment prevents development of cervical cancer and its consequences. OBJECTIVE: The present study evaluated the influence of the COVID-19 pandemic on cervical cancer screening by comparing the quantity of tests to detect cervical cellular changes performed in São Paulo state in 2019, prior to the detection of SARS-CoV-2 in Brazil, to the first (2020) and second (2021) years following its appearance. MATERIALS AND METHODS: Data from Fundação Oncocentro de São Paulo (FOSP), the agency that analyses approximately 220,000 Papanicolaou (Pap) tests annually, were reviewed. RESULTS: A median of 1,835 Pap tests were performed in 55 municipalities in 2019. This was reduced to 815 tests in 2020, a 56% decrease (p = 0.0026). In 2021, the median number was 1,745, a 53% increase over 2020 levels (p = 0.0233). The 26 municipalities with >1,000 tests in 2020 had a median reduction from 4,433 in 2019 to 2,580 in 2020 (p = 0. 0046). The 29 municipalities with <1,000 tests had a median reduction from 951 in 2019 to 554 in 2020 (p < 0.0001). There was a 44% reduction in the number of follow-up cytological evaluations from 2019 to 2020, followed by a 30% increase in the following year. However, the percentage of women with a normal finding or with any abnormality remained unchanged. The findings from a histological evaluation of women in São Paulo city indicated that the percent of cases positive for CIN-1 (p < 0.0410) and CIN-3 (p < 0.0012) increased in 2020 and 2021 as compared to 2019 levels. CONCLUSION: A reduction in testing for cervical cancer in the first year of the COVID-19 pandemic, accompanied by an elevated incidence of precancerous lesions in each of the first 2 years following its initiation, may portend a subsequent increased occurrence of cervical cancer in Brazil.

The Changing Epidemiology of Hepatitis C Virus Acquisition Among HIV-Infected Individuals in Brazil.

Identification of mechanisms of hepatitis C virus (HCV) acquisition among HIV-infected people is critical for prevention guidance. The aim of this study was to investigate risk factors for HCV infection and variations in HCV genotype distribution in a cohort of HIV-HCV coinfected patients in Brazil. This was a cross-sectional observational epidemiological study of a cohort of HIV-HCV coinfected individuals seen at a referral center for HIV-infected patients in the city of São Paulo between January and December 2017. The time of HCV acquisition, as determined by chart review, was categorized as before 2000, between 2000 and 2009, and from 2010 onward. HCV genotypes were determined by gene amplification and analysis. Among 3,143 HIV-infected individuals analyzed, 362 (11.5%) were HCV-HIV coinfected. Overall, the reported modes of HCV acquisition were sexual exposure in 172 (47.5%), injection drug use (IDU) in 86 (23.8%), use of inhaled drugs in 67 (18.5%) and blood transfusion in 10 (2.8%) individuals. All individuals who acquired HCV after IDU became infected before 2010. HCV acquisition by sexual contact was reported by 26.4%, 65.9%, and 63.8% of patients before 2000, between 2000 and 2009, and from 2010, respectively. There was an increase (p < .001) in the proportion of cases due to sexual transmission from the period before 2000 (26.4%) to between 2000 and 2009 (65.9%). There was no corresponding increase from 2000 and 2009 to after 2010 (p = .751). HCV genotype 1 was most prevalent at all time periods. The genotype 3 frequency decreased over time (test for trend p < .001), whereas genotype 4, extremely uncommon before 2010, became the second most prevalent genotype from 2010 onward. In HIV-infected individuals in Sao Paulo, Brazil, sexual transmission has replaced IDU as the most frequent mode of HCV acquisition.

Survival analysis over a 20-year period of a Brazilian cohort of blood donors coinfected HIV-HCV

ABSTRACT Among individuals coinfected with HCV and HIV, studies of mortality from non-hepatic causes have shown inconsistent results. The aim of this study was to investigate the contribution of HCV and HIV co-infection to mortality from hepatic and non-hepatic causes in Brazil. This retrospective cohort study included blood donors from Fundação Pró-Sangue de São Paulo (FPS) who were followed from 1994 to 2016 to compare mortality and its causes between HIV-HCV coinfected individuals versus those seronegative for all tested infections. Records from the FPS database and the Mortality Information System were linked through a probabilistic record Relationship (RL). The Hazard Ratio (HR) was estimated using Cox multiple regression models. HCV-HIV coinfected individuals compared to seronegative individuals had a higher risk of death from all causes (HR = 14.54), non-liver neoplasms (HR = 2.55), infections (HR = 10.37) and liver disease (HR = 7.0). In addition, HCV mono-infected individuals compared to seronegative individuals had a higher risk of death from all causes (HR = 2.23), liver cancer (HR = 32.21), liver disease (HR = 14.92), infection (HR = 3.22), and trauma (HR = 1.68). Individuals coinfected with HCV and HIV have increased overall mortality and death due to infections, liver diseases and non-liver neoplasms as compared to those uninfected with HCV and HIV.

Characterization of primary direct-acting antiviral (DAA) drugs resistance mutations in NS5A/NS5B regions of hepatitis C virus with genotype 1a and 1b from patients with chronic hepatitis.

The Hepatitis C virus (HCV) infection is a public health problem. The high level of HCV replication and its lack of post-transcriptional correction mechanisms results in the emergence of viral variants and the difficulty in determining polymorphisms and variants that contain the substitutions associated with resistance towards new antivirals. The main focus of this study was to map the NS5A and NS5B polymorphisms and resistance mutations to new antiviral drugs in HCV strains genotype 1 from patients with chronic hepatitis C infection. Serum samples were collected from patients who underwent routine viral load tests at the Instituto Adolfo Lutz, Sao Paulo city, Brazil. A total of 698 and 853 samples were used for the characterization of NS5A and NS5B regions, respectively, which comprise the HCV genotypes 1a and 1b. The prevalence of resistance mutations found in the NS5A region was 6.4%, with Y93H, L31M, Q30R, and Y93N as the main resistance-associated substitutions (RAS). No NS5B-associated RAS was observed for any of the analyzed drugs. These findings support that the RAS test should be offered to individuals with poor response to double combination regimens prior to treatment initiation, thereby assisting strain vigilance and selection of effective treatment or retreatment options using DAA regimens.

Characterization of Severe Acute Respiratory Syndrome Coronavirus 2 Omicron Variant Shedding and Predictors of Viral Culture Positivity on Vaccinated Healthcare Workers With Mild Coronavirus Disease 2019.

In this prospective cohort of 30 vaccinated healthcare workers with mild Omicron variant infection, we evaluated viral culture, rapid antigen test (RAT), and real-time reverse-transcription polymerase chain reaction (RT-PCR) of respiratory samples at days 5, 7, 10, and 14. Viral culture was positive in 46% (11/24) and 20% (6/30) of samples at days 5 and 7, respectively. RAT and RT-PCR (Ct ≤35) showed 100% negative predictive value (NPV), with positive predictive values (PPVs) of 32% and 17%, respectively, for predicting viral culture positivity. A lower RT-PCR threshold (Ct ≤24) improved culture prediction (PPV = 39%; NPV = 100%). Vaccinated persons with mild Omicron infection are potentially transmissible up to day 7. RAT and RT-PCR might be useful tools for shortening the isolation period.

Absence of neutralizing antibodies against the Omicron SARS-CoV-2 variant in convalescent sera from individuals infected with the ancestral SARS-CoV-2 virus or its Gamma variant.

OBJECTIVES: The aim of the present study was to evaluate if neutralizing antibody responses induced by infection with the SARS-CoV-2 strain that was dominant at the beginning of the pandemic or by the Gamma variant was effective against the Omicron variant. METHODS: Convalescent sera from 109 individuals, never exposed to a SARS-CoV-2 vaccine, who had mild or moderate symptoms not requiring hospitalization following either a documented SARS-CoV-2 ancestral strain infection or a Gamma variant infection, were assayed for in vitro neutralizing antibody activity against their original strains and the Omicron variant. RESULTS: Following an infection with the ancestral strain, 56 (93.3%), 45 (77.6%) and 1 (1.7%) serum sample were positive for neutralizing antibodies against the ancestral, Gamma variant, and Omicron variant, respectively. After infection with the Gamma variant, 43 (87.8%) and 2 (4.1%) sera were positive for neutralizing antibodies against the Gamma and Omicron variants, respectively. CONCLUSIONS: Neutralizing antibodies generated following mild or moderate infection with the SARS-CoV-2 ancestral strain or the Gamma variant are not protective against the Omicron variant.