COVID-Like Illness Respiratory Pathogens. A Prospective Cohort on the COVID-19 Post-acute Condition

Identifying multiorgan sequalae and complications through high quality, prospective matched controlled studies throughout the course of COVID-19 is important for the acute and long-term management of patients and for health systems' planning. Further, it is key to understand the link between acute illness and long term consequences particularly in those already living with other comorbidities such as cardiovascular diseases or cancer.

Since the clinical presentation of COVID-19 can resemble a variety of common respiratory infections, describing the distribution of pathogens and the severity of clinical presentation associated with COVID-like illnesses (CLI) infections is important to generate a baseline clinical description by comparing potential long-term effects of PCR-confirmed COVID-19 to those following other respiratory infections.

To gain a better understanding of the clinical burden on COVID-19 survivors we will undertake a comparative evaluation within a cohort of PCR-confirmed individuals with COVID-19 vs. those PCR-confirmed symptomatic individuals with other respiratory pathogens plus healthy individuals from the community.

The results will inform strategies to prevent long term consequences; inform clinical management, interventional research, direct rehabilitation, and inform public health management to reduce overall morbidity and improve outcomes of COVID-19.

This is an observational prospective matched cohort study to evaluate the post-acute consequences of the SARS-CoV-2 symptomatic infection (case-positives) while having as comparison groups (1) symptomatic controls (case-negatives) and (2) healthy controls, that are healthy individuals recruited from the same community of the cases, but not arise from the same household. After pre-screening of COVID-19 symptoms at the hospital and other satellite health centers, consenting/assenting patients of 16 years of age and above with all range of PCR-confirmed Covid-19 disease severity -from mild to severely ill hospitalized patients- will be recruited and matched to other Non-SARS-CoV-2 PCR-determined patients and to healthy community controls. Then, they will be followed up for 12 months (13 months after screening) to determine the occurrence of admissions, any outpatient encounter, symptoms (new or persistent) and concomitant use of medication after 28 days of diagnosis.

At recruitment, respiratory samples are collected for respiratory infections diagnosis. Also, blood samples are collected to generate baseline data on potential biomarkers associated to occurrence of investigated outcomes. This will include biochemistry (including inflammatory markers) and hematology as well as SARS-CoV-2 serology (IgG) which will also be taken at the end of follow up to rule out infection during the course of the follow up. Though, the serology testing won't be done along each recruitment but in batches during the study period. Clinical (symptoms and diagnosis), socioeconomic, demographic, household conditions, health seeking behavior and medical history information will be gathered.

Eligibility Criteria:
1. For symptomatic patients attending to the SFXH or other satellite health centers

   * Inclusion Criteria

     1. Patients \> or =16 years of age
     2. Presenting respiratory symptoms
     3. Positive respiratory sample for SARS-CoV-2 or other respiratory infections included in the panel
     4. Possibility to be contacted during follow-up
     5. Consented participation
     6. Patients which households are located within the study catchment area
   * Exclusion Criteria

     1. Symptomatic patients who test negative for all pathogens of the PCR-based respiratory panel.
     2. Symptomatic patients who test negative for the SARS-CoV-2 RDT and do not meet the matching criteria (age and residency (community)) as symptomatic controls to any of the recruited cases (to be considered as controls for the Antimicrobial Use Workpackage)
2. Antimicrobial Use Work package (A subset of hospitalized, symptomatic patients are to be recruited as control group for the Antimicrobial Use Workpackage, if they meet the inclusion criteria)

   * Inclusion Criteria

     1. Patients \> or =16 years of age
     2. Presenting respiratory symptoms
     3. Negative respiratory sample for SARS-CoV-2 (RDT)
     4. Do not meet the matching criteria (age and residency (community)) as symptomatic controls to any of the recruited cases
     5. Admitted to SFXH
     6. Consented participation
3. For healthy controls from the community

   * Inclusion Criteria

     1. Patients \> or =16 years of age
     2. Meet the age and residency (community) criteria to be matched to the cases
     3. Possibility to be contacted during follow-up
     4. Consented participation
   * Exclusion Criteria

     1. Presenting COVID-19 like symptoms
     2. Positive for SARS-CoV-2 RDT Eligible participants in the community presenting with an acute illness can be considered for inclusion as a case and recommended for referral to SFXH/ satellite health centre.