Participants not completing the longer-term symptom sections or stating they did not know if they had experienced longer-term symptoms were assumed to have missing information regarding longer-term symptoms; these individuals accounted for 4.3% of the unweighted sample. == Analyses == Analyses were conducted using SAS 9.4TMSoftware with PKR-IN-2 a two-tailed alpha level of 0.05. certainty they had been infected. However, the mean probability of having infection-related antibodies was not associated with contamination severity or the reporting of common longer-term COVID-19 symptoms. More than one in five adults were unaware they had been infected. == Conclusion == Self-report surveys may misclassify the SARS-CoV-2 contamination status of a substantial proportion of untested people and may bias estimates of the percentage infected, the severity of infections and the risk of developing infection-related longer-term symptoms. Common longer-term COVID-19 symptoms reported by some could have been caused by other infections or diseases. Keywords:SARS-CoV-2, COVID-19, post-COVID condition, antibodies, cross-sectional survey == Introduction == An estimated 16.0% of Canadians who self-report a confirmed or suspected SARS-CoV-2 infection develop post COVID-19 condition (PCC), also known as long COVID ((1)). Even people with moderate or asymptomatic infections are at risk of developing PCC, although to a lesser extent than those with more severe symptoms ((24)). However, these longer-term symptoms attributed to COVID-19 can be generated by other infections or diseases ((5)). Consequently, in the absence of a control group, the occurrence of PCC could be overestimated in a populace ((6)). A variety of methods, including self-report and antibody screening, have been used to estimate the prevalence of SARS-CoV-2 infections and related longer-term symptoms, but the impact of employed methods on conclusions has not been thoroughly explored ((7)). The second cycle of the Canadian COVID-19 Antibody and Health Survey (CCAHS-2) provides an opportunity to address this knowledge gap. In addition to self-reported infection status, the survey captured information on SARS-CoV-2 antibodies due to infection and asked all respondents, irrespective of infection status, about their experiences with common longer-term COVID-19 symptoms. The objectives of this study are to describe the self-reported SARS-CoV-2 infection status and antibody test results of adults who were surveyed between April and August 2022, quantify the agreement between self-reported SARS-CoV-2 infection status and the presence of antibodies indicating a past infection and examine how self-reported common longer-term COVID-19 symptoms vary by self-reported infection status and antibody results. Our findings contribute to an evidence base that can be used to support the interpretation of research that relies on serology or PKR-IN-2 self-report when assessing the burden of SARS-CoV-2 infections and PCC. == Methods == == Data source == The CCAHS-2 is a large population-based cross-sectional multistage probability survey of the Canadian adult population, aged 18 years and older, living in private dwellings across the 10 provinces that was conducted between April and August 2022 ((8)). In addition to using an electronic questionnaire to capture information on SARS-CoV-2 infection history and common longer-term symptoms of COVID-19 since the start of the pandemic, the survey collected a dried blood spot (DBS) sample to measure the presence PKR-IN-2 of antibodies against SARS-CoV-2 from vaccination or prior infection. Over 100,000 (n=105,998) adults were invited to participate and 15,701 completed at least part of the electronic questionnaire, provided a DBS sample and agreed to share their data with the Public Health PKR-IN-2 Agency of Canada for an overall response rate of 14.8%. Except for antibody testing, results presented are based on self-reports and relate to the first SARS-CoV-2 infection with a positive test result or, in the absence of a positive test result, the first suspected infection. Additional methodological considerations and relevant questions that were asked to respondents are available in theAppendix. == Rabbit Polyclonal to SLC25A12 Probability of the presence of antibodies from a past SARS-CoV-2 infection == Statistics Canada derived a variable that specifically estimated PKR-IN-2 the probability of the presence of antibodies from a past SARS-CoV-2 infection. This was done using information on the presence and quantity of nucleocapsid, spike and receptor binding domain of spike antibodies combined with results from a nucleocapsid cross-calibration study involving the two laboratories that conducted all the DBS sample testing. Briefly, spike and receptor binding domain of spike antibody positivity were based on lab-specific predetermined thresholds. If both tests were.