Cohort Profile: A longitudinal Victorian COVID-19 cohort (COVID PROFILE)

Purpose The COVID PROFILE cohort is a longitudinal clinical study based in Victoria Australia, which was established to understand immunity to SARS-CoV-2 in a low transmission population setting and to identify immunological markers of long-term immunity and immune-dysregulation after both infection and vaccination. Additionally, this cohort was established as a biobank resource for researchers to address other health-related immunological questions. Participants We enrolled 178 adult community members, including household contacts, who had either recovered from a SARS-CoV-2 infection or were SARS-CoV-2 naïve. Only participants ≥18 years of age and, in the case of female participants, non-pregnant women at the time of enrollment were included in the study. Detailed COVID-19 clinical data, vaccination status, medical history and demographics was collected. Findings to date At enrollment, we found that 87.8% of COVID-19 recovered individuals were seropositive with detectable levels of anti-SARS-CoV-2 IgG antibodies. Seronegative COVID-19 recovered individuals included asymptomatic individuals or participants that were enrolled more than 12 months after their COVID-19 diagnosis. Except for one individual who was seropositive at baseline despite a previous SARS-CoV-2 PCR negative diagnosis, all household contacts and other community members enrolled as SARS-CoV-2 PCR negative, were seronegative for all SARS-CoV-2-specific antibodies tested. The infection rate (re-infection or new infection) during 24 months of the study was 42.7%, as determined by either rapid antigen tests, PCRs or serology screens. Of the SARS-CoV-2 recovered participants, 32.6% reported ongoing symptoms at enrollment of which 47% had already experienced ongoing symptoms for more than 12 weeks. Future Plans COVID PROFILE will be used to comprehensively understand temporal immunity to SARS-CoV-2 and COVID-19 vaccines and to understand the impact of host immunological composition on such immunity and symptom severity. Additionally, studies focusing on understanding immunity following breakthrough infections and immunological risk factors that contribute towards development of long COVID are planned. Limitations/Strengths of the study ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work was made possible through Victorian State Government Operational Infrastructure Support and Australian Government NHMRC IRIISS. This work was supported by WHO Unity funds (2020/1085469-0) and WEHI Philanthropic funds. The funders had no role in study design, data collection and analysis. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: Ethics committee of the Walter and Eliza Hall Institute (WEHI) and Melbourne Health Human Research Committees gave ethical approval for this work I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines, such as any relevant EQUATOR Network research reporting checklist(s) and other pertinent material, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors