An observational study in Respiratory Syncytial Virus Infections, Immunocompromised Host and Influenza, sponsored by Hospital Italiano de Buenos Aires. Active, not recruiting. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2026-09-11.
Sponsored by Hospital Italiano de Buenos Aires · Observational
Respiratory syncytial virus (RSV), influenza, and SARS-CoV-2 are common respiratory viruses. In healthy adults they usually cause mild, cold-like illness, but in people whose immune system is severely weakened - such as people who have had a bone marrow, stem cell, or organ transplant, people being treated for cancer or blood disorders, or people taking medicines that suppress the immune system - these infections can be much more serious, sometimes spreading from the nose and throat down into the lungs and leading to hospitalization, intensive care, or death.
This study looks back at medical records from a large hospital network in Buenos Aires, Argentina, covering two periods (November 2011 to March 2020, and May 2022 to December 31, 2025) to describe what happens to adults with severely weakened immune systems after they are diagnosed with RSV, influenza, or SARS-CoV-2.
For each of these three viruses, researchers will separately describe how sick patients were on the day of diagnosis and again 7 and 30 days later; whether the infection spread from the upper airway down into the lungs; how often patients needed to be hospitalized or admitted to an intensive care unit; how long hospital stays lasted; and how many patients died within 30 days. The study will also look for patient characteristics - such as the type of immune weakness, low blood cell counts, or vaccination status - that are linked to worse outcomes within each virus group. The three viruses are described separately and are not statistically compared against one another.
This is a review of existing medical record information only. No new tests, procedures, or treatments will be given to patients as part of the study, and no patient will be contacted; all information comes from data already collected during routine medical care. This study is conducted under a research agreement with Pfizer.
Background and rationale. Respiratory syncytial virus (RSV) is increasingly recognized as a significant cause of morbidity and mortality in adults, particularly those over 65 years of age and those with underlying comorbidities. In immunocompromised adults, RSV infection can progress from an upper respiratory tract infection (URTI) to a lower respiratory tract infection (LRTI), with reported progression rates of 19%-36% depending on the degree of immunosuppression, presence of lymphopenia, and associated comorbidities. In recipients of allogeneic hematopoietic stem cell transplantation (HSCT), RSV-related LRTI mortality has been reported to range from 10% to 40%, particularly among patients with graft-versus-host disease and prolonged neutropenia. Among solid organ transplant recipients, complications appear less frequent overall, though lung transplant recipients and those experiencing acute rejection or graft dysfunction remain at elevated risk. Despite this burden, there is no antiviral treatment specifically approved for RSV in adults, and management remains largely supportive. Influenza and SARS-CoV-2 pose analogous risks in severely immunosuppressed populations, and the recent approval of RSV vaccines for adults over 60 and for adults aged 18-59 with immunocompromising conditions makes it clinically important to better characterize the burden and clinical course of these three viral infections in this population, to inform vaccination policy and clinical management.
Setting. The study is conducted within the Hospital Italiano de Buenos Aires (HIBA) network, an integrated, high-complexity, university-affiliated healthcare system in the Autonomous City of Buenos Aires comprising a main campus and a second site (San Justo), with 789 beds (246 critical care beds), approximately 2.5 million outpatient visits per year, and roughly 41,000 discharges annually. All clinical care across the network is documented in a single, unified electronic health record (EHR) system, in which comorbidities and diagnoses are automatically mapped to the SNOMED controlled vocabulary through an institutional terminology server.
Design and population. This is a retrospective cohort study of all adults with severe immunosuppression who had a laboratory-confirmed diagnosis of RSV, influenza, or SARS-CoV-2, obtained by multiplex PCR of a nasopharyngeal swab or bronchoalveolar lavage sample, between November 1, 2011 and March 20, 2020, and from May 1, 2022 to December 31, 2025, within the Hospital Italiano de Buenos Aires (HIBA) network. Enrollment was interrupted between March 20, 2020 and May 1, 2022, corresponding to the period of most significant restructuring of hospital services during the COVID-19 pandemic response. During this interval, admission thresholds and practice patterns changed substantially - at times nearly all diagnosed patients were hospitalized regardless of clinical severity - which would have introduced systematic bias into severity-based outcome measures such as the ordinal clinical status scale; this period was therefore excluded. The total observation window spans approximately 140 non-consecutive months. Severe immunosuppression is defined broadly and includes, among other conditions: active leukemia or lymphoma, disseminated malignancy, aplastic anemia, graft-versus-host disease, congenital immunodeficiencies, treatment with immune checkpoint inhibitors, solid organ transplantation on immunosuppressive therapy, hematopoietic stem cell transplantation within two years or ongoing immunosuppressive therapy, high-dose systemic corticosteroids, alkylating agents or antimetabolites at specified thresholds, TNF-alpha inhibitors, lymphocyte-depleting or B-cell depleting biologic agents, and HIV infection with a CD4 count below 200 cells/mm³, an AIDS diagnosis, or symptomatic HIV. Diagnostic methods for viral detection evolved over the study period, from an in-house multiplex PCR platform with capillary electrophoresis (validated in November 2011, detecting a broad panel of respiratory viruses including RSV) to a commercial FTD Respiratory Pathogens 21 panel used in 2019, and the BIOFIRE FILMARRAY Respiratory 2.1 Panel implemented from January 2020 onward. Patients vaccinated against RSV prior to their acute respiratory infection episode are excluded from the cohort (applicable to the later study period only, coinciding with RSV vaccine availability in Argentina); RSV vaccination status is recorded to enable transparent reporting of this exclusion.
Data source and handling. All data will be extracted from the institutional EHR using automated queries, without manual chart abstraction, and will be fully de-identified before analysis. The resulting dataset will be stored on a password-protected computer accessible only to the study's principal investigator and will be permanently deleted upon completion of the statistical analysis.
Planned analysis. Baseline characteristics will be summarized using medians and interquartile ranges for continuous variables and absolute/relative frequencies for categorical variables. The association between candidate predictors and dichotomous outcomes (progression from URTI to LRTI, ICU admission, and 30-day mortality) will be assessed using bivariate and multivariable logistic regression, reporting odds ratios with 95% confidence intervals. An ordinal logistic regression model for proportional odds will be used to assess predictors of the ordinal clinical status outcome at days 0, 7, and 30, with the proportional odds assumption tested using the Brant test; models for clinical status at days 7 and 30 will be adjusted for baseline status. Each virus (RSV, influenza, and SARS-CoV-2) will be analyzed using a separate model; no formal statistical comparison between viruses will be performed. While the primary follow-up window for clinical status, hospitalization, and mortality outcomes is 30 days, patients will be followed for up to 366 days to ascertain major cardiovascular events (acute coronary syndrome or cerebrovascular accident) as a secondary outcome. A p-value below 0.05 will be considered statistically significant. All analyses will be performed using STATA version 16 MP.
Ethical considerations. As a minimal-risk, retrospective study using fully de-identified data with no patient contact and no manual chart review, the study was approved with a waiver of informed consent by the Hospital Italiano de Buenos Aires Research Ethics Committee (Comité de Ética en Protocolos de Investigación, CEPI; approval No. 7738), consistent with CIOMS 2019 Guideline 10 on modifications and waivers of informed consent. The study is conducted in accordance with Argentine Ministry of Health Resolution 1480/2011, Law 3301/09 of the City of Buenos Aires, the Declaration of Helsinki, the ICH E6 Good Clinical Practice guidelines, and Argentine data protection law (Law 25.326, Habeas Data). The study is conducted under a research agreement with, and is funded by, Pfizer (NISAMR 2025010848).
306 studies on the registry are indexed under Respiratory Syncytial Virus Infections; 50 are open to participants now.
This study's enrollment of 350 is close to the median of 375 across 76 observational studies indexed under Respiratory Syncytial Virus Infections.
Browse Respiratory Syncytial Virus Infections studies →Hospital Italiano de Buenos Aires is the lead sponsor of 133 studies on the registry; 24 are open to participants now.
Counted across the registry records on this site, refreshed daily.
The study population consists of all adults treated within the Hospital Italiano de Buenos Aires (HIBA) network - a high-complexity, university-affiliated healthcare system in Buenos Aires, Argentina - who met criteria for severe immunosuppression and had a laboratory-confirmed diagnosis of RSV, influenza, or SARS-CoV-2 by multiplex PCR, between November 1, 2011 and March 20, 2020, and from May 1, 2022 to December 31, 2025. All patient care is documented in a single EHR system, from which the population was identified through automated, retrospective queries, without manual chart review, regardless of care setting (outpatient, emergency department, ward, or ICU).
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Presence of severe , defined as any of the following:
Suspected acute viral respiratory infection, defined per European Conference on Infections in Leukemia (ECIL) criteria as meeting all of the following: clinical suspicion recorded in the electronic health record; positive multiplex PCR for RSV, SARS-CoV-2, or influenza; and fulfillment of criteria for either upper (URTI) or lower respiratory tract infection (LRTI).
Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
After a transplant from a donor, the donor’s immune cells attack the recipient’s body, often the skin, gut or liver.
PD-1, PD-L1 and CTLA-4 are proteins that act as brakes on the immune system. Checkpoint inhibitors, such as pembrolizumab or nivolumab, block them so the immune system can attack a cancer.
PD-L1 can also be measured in a tumour sample. Some scores count stained tumour cells only (TPS); others also count certain immune cells (CPS). The study names the score and the minimum it uses.
Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
The number of CD4 cells, a type of white blood cell, in a given amount of blood. It is used to follow how well the immune system is doing in HIV.
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Immunosuppression
A weakened immune system. It can come from an illness, such as HIV or some blood cancers, or from medicines that turn the immune system down, for example after an organ transplant or for an autoimmune disease; steroids at higher doses count.
Read whether the line is about a condition or about medicines, and which medicines and doses it means.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Cancer (malignancy)
Malignancy means cancer. Criteria about another or earlier malignancy ask whether you have had a different cancer, usually within a set number of years.
Some are commonly allowed, such as treated skin cancers other than melanoma and early cancers removed completely — check the exceptions this study lists.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
GVHD (graft-versus-host disease)
After a transplant from a donor, the donor’s immune cells attack the recipient’s body, often the skin, gut or liver.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
PD-1, PD-L1 and checkpoint inhibitors
PD-1, PD-L1 and CTLA-4 are proteins that act as brakes on the immune system. Checkpoint inhibitors, such as pembrolizumab or nivolumab, block them so the immune system can attack a cancer.
PD-L1 can also be measured in a tumour sample. Some scores count stained tumour cells only (TPS); others also count certain immune cells (CPS). The study names the score and the minimum it uses.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Allogeneic and autologous transplant
Stem cell (bone marrow) transplants. Allogeneic uses cells from a donor; autologous uses your own cells, collected earlier and given back.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Corticosteroids (steroids)
Anti-inflammatory medicines such as prednisone, prednisolone and dexamethasone — not the anabolic steroids used for muscle.
Studies differ in what they allow: check which steroid medicines, routes (tablets, injections, creams, inhalers, eye drops) and doses this study accepts.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
HIV
The human immunodeficiency virus, which weakens the immune system.
Many studies now accept people whose HIV is controlled on treatment, judged by the viral load and the CD4 count. Check the limits this study sets.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
CD4 count
The number of CD4 cells, a type of white blood cell, in a given amount of blood. It is used to follow how well the immune system is doing in HIV.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Life expectancy
The study doctor’s estimate of how long someone is likely to live. Criteria use it so that people can stay in the study long enough for it to answer its question.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Adults with severe immunosuppression and a laboratory-confirmed diagnosis of acute viral respiratory infection due to respiratory syncytial virus (RSV) by multiplex PCR, meeting criteria for upper or lower respiratory tract infection, between November 1, 2011 and March 20, 2020, and from May 1, 2022 to December 31, 2025.
Adults with severe immunosuppression and a laboratory-confirmed diagnosis of acute viral respiratory infection due to influenza by multiplex PCR, meeting criteria for upper or lower respiratory tract infection, during the same study period.
Adults with severe immunosuppression and a laboratory-confirmed diagnosis of acute viral respiratory infection due to SARS-CoV-2 by multiplex PCR, meeting criteria for upper or lower respiratory tract infection, during the same study period.
Ordinal clinical status score
Clinical status assessed using a 6-category mutually exclusive ordinal scale (Davey et al.): discharged with full recovery; discharged but not back to normal activities; hospitalized without oxygen requirement; hospitalized with oxygen requirement; ICU admission; death. Assessed separately within each of the RSV, influenza, and SARS-CoV-2 cohorts; no formal comparison between cohorts is performed.
Time frame: Day 0, Day 7, and Day 30 after diagnosis
Progression from upper to lower respiratory tract infection
Proportion of patients initially meeting criteria for upper respiratory tract infection (URTI) who develop new lower respiratory symptoms plus radiologic evidence of new pulmonary lesions.
Time frame: Within 48 hours to 30 days of diagnosis
Hospitalization
Proportion of patients requiring hospitalization; among patients initially managed as outpatients, hospitalization occurring within 30 days of the positive PCR result.
Time frame: Within 30 days of diagnosis
Length of hospital stay
Total number of days between hospital admission and discharge (including transfer, discharge, or death), among hospitalized patients.
Time frame: Through hospital discharge, up to 30 days
ICU admission
Proportion of patients requiring admission to an intensive care unit (intermediate care, adult ICU, or coronary unit) for respiratory or hemodynamic support.
Time frame: Within 30 days of diagnosis
ICU length of stay
Number of days from ICU admission to discharge from the hospital (transfer to general ward, hospital discharge, transfer to another center, or death).
Time frame: Through hospital discharge, up to 30 days
All-cause 30-day mortality
Death from any cause within 30 days of the positive PCR result for the respiratory virus.
Time frame: 30 days after diagnosis
Outpatient and emergency department visits
Number of visits to the emergency department or to a primary care physician, internist, pulmonologist, or other relevant specialist, with a reason for visit related to the viral infection or worsening of a related comorbidity.
Time frame: Within 30 days of diagnosis
Major cardiovascular events
Occurrence of acute coronary syndrome or cerebrovascular accident.
Time frame: Within 366 days of diagnosis
Predictors of worse clinical outcomes, by virus
Association between candidate predictors (type of immunosuppression, cytopenias, chest imaging findings, comorbidities, vaccination status, etc.) and progression to LRTI, ICU admission, and 30-day mortality, assessed by logistic regression within each virus-specific cohort (RSV, influenza, SARS-CoV-2 analyzed separately).
Time frame: Within 30 days of diagnosis
No study locations are listed for this record.
Plan to share: No — The final database will be stored on a password-protected computer accessible only to the study's principal investigator and will be deleted upon completion of the statistical analysis.
Ran from Nov 2011 to primary completion in Dec 2025, 169 months.
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This study is active, not recruiting, as verified in Sep 2026. You cannot join it, but the record below documents what was studied.
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