Retrospective Review of Prenatal Gonorrhea and Chlamydia Screening in Alberta: 2018-2022.

A retrospective 5-year province-wide evaluation of prenatal Neisseria gonorrhoeae (GC) and Chlamydia trachomatis (CT) screening in Alberta, Canada, was carried out to assess compliance with the provincial recommendations for universal prenatal screening as a prevention for neonatal ophthalmia. Screening generally improved across the province each year, 82.1% in 2018 and reaching 87.3% in 2022. Women in the age group under 25 years were the most likely to not have the recommended first-trimester screening and demonstrated the highest prevalence of GC and CT infections. The results of this investigation demonstrate that continued improvements are needed to achieve universal prenatal GC/CT screening in Alberta.

Evaluation and comparison of risk-based and universal prenatal HCV screening programs in Alberta, Canada.

BACKGROUND & AIMS: Canadian clinical practice guidelines currently recommend risk-based screening for HCV in pregnant individuals. However, no provinces or territories have ever compared the effectiveness of risk-based vs. universal screening for the prenatal diagnosis of HCV. We aimed to evaluate and compare HCV screening programs after implementing a universal population-level pilot program among prenatal patients in Alberta, Canada. METHODS: The Alberta Prenatal Screening Program for Select Communicable Diseases was amended to include universal HCV antibody screening. Cohorts of pregnant individuals screened for HCV through risk-based or universal programs were generated over 1-year periods. HCV screening rates and prevalence were analyzed and compared between cohorts to evaluate the effectiveness of screening methods. Social and demographic risk factors for HCV-positive individuals were compared between screening cohorts to identify which populations may be overlooked with risk-based guidelines. RESULTS: HCV antibody screening rates were 11.9% and 99.9% among pregnant individuals in the risk-based and universal cohorts, respectively. HCV prevalence among the cohorts was 0.07% and 0.11% (difference = 0.04%, p = 0.032), with an average of 21 additional HCV-positive pregnant individuals identified annually with universal screening. HCV-positive pregnant patients diagnosed through universal screening were more likely to engage in high-risk sexual behaviours/sex work compared to those diagnosed through risk-based screening (47.6% vs. 12.5%, respectively p = 0.035), suggesting that these high-risk cases are being missed by risk-based screening. CONCLUSIONS: Universal HCV screening diagnoses significantly higher numbers of pregnant individuals infected with HCV compared to risk-based screening. Universal HCV screening or amending risk-based guidelines to incorporate more proxy variables for risk factors should be considered to improve prenatal HCV screening guidelines in Canada and help achieve HCV elimination in the next decade. IMPACT AND IMPLICATIONS: HCV is a bloodborne pathogen that can cause severe liver disease and be vertically transmitted from a mother to her baby during pregnancy. Pregnant individuals in Alberta are currently only tested for HCV if they disclose engaging in activities that put them at risk of acquiring the infection (risk-based screening). Using a population-wide universal prenatal HCV screening program, our work shows that testing based on patient disclosed risk alone leads to the significant underdiagnosis of HCV in pregnant individuals and suggests individuals engaging in sex work or risky sexual behaviours are being overlooked by the current risk-based program. Our outcomes represent the first province-wide study to evaluate and compare prenatal HCV risk-based and universal screening programs in Canada and provide evidence to support the update of prenatal HCV screening policies across the country and in similar jurisdictions.

Examination of Care Milestones for Preventing Congenital Syphilis Transmission Among Syphilis-Infected Pregnant Women in Alberta, Canada: 2017-2019.

BACKGROUND: An infectious syphilis outbreak in Alberta has resulted in increased congenital syphilis (CS) cases. To shed light on potential risk factors, we used administrative data sets to examine care milestones for the prevention of CS among pregnant women diagnosed with syphilis, as well as correlates of women giving birth to infants with CS. METHODS: Provincial administrative databases were used to identify and describe pregnant women diagnosed with any stage of infectious or noninfectious syphilis who gave birth in Alberta between January 1, 2017, and December 31, 2019. Data on prenatal care, syphilis screening, and syphilis medication dispensation were used to evaluate the care milestones. Clinical care and maternal demographics were assessed using logistic and linear regression analyses to determine correlates for missed care milestones or a newborn outcome of CS. RESULTS: Of 182 syphilis-infected pregnant women, 63 (34.6%) delivered a newborn with CS. Overall, in the first trimester, 136 (75.1%) women had a health care visit, 72 (39.6%) had a prenatal care visit, 71 (39.0%) were screened for syphilis, and 44 (24.2%) were treated. Gestational time to treatment initiation (adjusted odds ratio, 1.04; 95% confidence interval, 1.02-1.06) and older maternal age at diagnosis (adjusted odds ratio: 1.28, 95% confidence interval, 1.08-1.50) were independently associated with CS outcomes. No variables were found to be independently associated with a health care visit, prenatal screening, or initiation of treatment. CONCLUSIONS: Although nearly two-thirds of CS cases were prevented, there remained missed opportunities in the prevention of CS. Early treatment, which relies on timely access to prenatal care and screening, was the most important for the prevention of CS.

Identifying gaps in the treatment of hepatitis C in patients co-infected with HIV in Edmonton, Alberta.

INTRODUCTION: With the availability of direct-acting antivirals, Hepatitis C (HCV) is now considered a treatable disease. Patients who are co-infected with human immunodeficiency virus (HIV) and HCV represent an ideal patient population to treat for HCV, as (1) patients are routinely taking medication for HIV, and therefore would be able to complete HCV drug regimens, and (2) HIV infection has been shown to increase HCV disease progression. OBJECTIVE: We sought to determine the occurrence of HCV co-infection among HIV patients in our provincial cohort, determine whether they received treatment for HCV, and identify currently viremic patients who can be linked to care. MATERIALS AND METHODS: HCV laboratory testing data (HCV antibody and HCV RNA) and HCV medication dispensation data was collected for all HIV positive patients. Current and previous HCV infection and treatment was assessed. Chart reviews were conducted for HCV viremic patients to assess their HIV care and social determinants. RESULTS: Of the 2417 HIV positive patients, 392 (16.2%) were identified as being co-infected with HCV. 198 (50.5%) of the HIV-HCV co-infected patients received HCV treatment and 232 (59.2%) were not viremic on the most recent HCV RNA test. 99 (69.2%) had a suppressed HIV infection suggesting they are active in their HIV care and good candidates for HCV treatment. CONCLUSION: Despite the availability of direct-acting antivirals, many patients who are co-infected with HIV and HCV are not being treated for HCV. Routine surveillance of HIV-HCV co-infected patients could improve HCV treatment rates in a high-risk population.

Evaluation of Six Commercial Mid- to High-Volume Antibody and Six Point-of-Care Lateral Flow Assays for Detection of SARS-CoV-2 Antibodies.

Coronavirus disease (COVID) serological tests are essential to determine the overall seroprevalence of a population and to facilitate exposure estimates within that population. We performed a head-to-head assessment of enzyme immunoassays (EIAs) and point-of-care lateral flow assays (POCTs) to detect severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies. Demographics, symptoms, comorbidities, treatment, and mortality of patients whose sera were used were also reviewed. Six EIAs (Abbott, Affinity, Bio-Rad, DiaSorin, Euroimmun, and Roche) and six POCTs (BTNX, Biolidics, Deep Blue, Genrui, Getein BioTech, and Innovita) were evaluated for the detection of SARS-CoV-2 antibodies in known COVID-19-infected individuals. Sensitivity of EIAs ranged from 50 to 100%, with only four assays having overall sensitivities of >95% after 21 days after symptom onset. Notably, cross-reactivity with other respiratory viruses (parainfluenza virus [PIV-4] [n = 5], human metapneumovirus [hMPV] [n = 3], rhinovirus/enterovirus [n = 1], CoV-229E [n = 2], CoV-NL63 [n = 2], and CoV-OC43 [n = 2]) was observed; however, overall specificity of EIAs was good (92 to 100%; all but one assay had specificity above 95%). POCTs were 0 to 100% sensitive >21 days after onset, with specificity ranging from 96 to 100%. However, many POCTs had faint banding and were often difficult to interpret. Serology assays can detect SARS-CoV-2 antibodies as early as 10 days after symptom onset. Serology assays vary in their sensitivity based on the marker (IgA/IgM versus IgG versus total) and by manufacturer; however, overall only 4 EIAs and 4 POCTs had sensitivities of >95% >21 days after symptom onset. Cross-reactivity with other seasonal coronaviruses is of concern. Serology assays should not be used for the diagnosis of acute infection but rather in carefully designed serosurveys to facilitate understanding of seroprevalence in a population and to identify previous exposure to SARS-CoV-2.

Overview of a Provincial Prenatal Communicable Disease Screening Program: 2002-2016.

OBJECTIVE: This study sought to provide a 14-year overview of serological results from a provincial prenatal screening program. METHODS: Prenatal screening data from August 2002 to December 2016 were extracted from the Alberta Public Health Laboratory (ProvLab) Information system. Data were analyzed by year, communicable disease marker, test result, and maternal age category. The age-stratified proportion of seropositive results for hepatitis B virus, human immunodeficiency virus, and syphilis was determined, and the proportion of seronegative results was determined for rubella and varicella. The Mann Kendall Trend Test was performed to identify significant temporal trends in the results (Canadian Task Force Classification II-2). RESULTS: In total 821 910 prenatal specimens were examined. Overall, the proportion of prenatal specimens positive for hepatitis B virus showed a slight statistically significant upward trend from 0.50% in 2003 to 0.58% in 2016 (P = 0.03). The proportion of positive human immunodeficiency virus prenatal specimens showed no significant trend over the study period. The proportion of positive syphilis specimens increased from 2006 to 2008 (0.07% to 0.21%; P < 0.0001) and stayed relatively constant until a decrease began in 2015. The proportion of seronegative specimens for varicella and rubella showed a significant upward trend of 0.48% per year (P < 0.01) and 0.88% per year (P < 0.01), respectively. CONCLUSION: The Alberta Prenatal Screening Program for Selected Communicable Diseases presents a unique data set that allows us to look at screening results on a provincial level. Trends in results are reflective of communicable disease trends in the general population and should be monitored for effective infectious disease management of the maternal and newborn population.

A Retrospective Review of Treatment Failures Using Azithromycin and Doxycycline in the Treatment of Rectal Chlamydia Infections in Women and Men Who Have Sex With Men.

We examined the prevalence of rectal chlamydia treatment failures in men who have sex with men and women attending Alberta sexually transmitted infection clinics. Among those completing a test of cure, there was no significant difference among patients treated initially with azithromycin (treatment failure, 39/460 [8.5%]; 95% confidence interval, 5.9%-11.0%) compared with patients treated with doxycycline (0/16; 95% confidence interval, 0%-0.2%; P = 0.63).

Evidence for increased Chlamydia case finding after the introduction of rectal screening among women attending 2 Canadian sexually transmitted infection clinics.

BACKGROUND: Chlamydia trachomatis is the most common notifiable disease in Canada, and extragenital sites are believed to serve as hidden reservoirs for ongoing transmission of infection. There are no specific Canadian screening guidelines for asymptomatic individuals from extragenital sites. We sought to determine the prevalence and factors associated with rectal C. trachomatis among female sexually transmitted infection (STI) clinic attendees in Alberta, Canada. METHODS: Between 20 July and 31 December 2012, all female attendees at 2 Provincial STI clinics receiving a pelvic examination, regardless of a history of anal intercourse, were screened for rectal C. trachomatis using the Gen-Probe Aptima COMBO 2 Assay. Demographic and behavior variables were compared between rectal-only chlamydia cases and genitourinary cases using χ(2) or Fisher exact test, Mann-Whitney test, and logistic regression. RESULTS: A total of 3055 women were screened for rectal chlamydia. The prevalence of rectal chlamydia ranged from 11.7% to 13.5%. There were 133 rectal-only cases, increasing case detection by 44.3% from 300 genitourinary cases to 433 total cases, ranging from 21.7% to 88.2% by clinic. Women who were a contact to an STI were less likely to have rectal-only chlamydia for both clinics (P ≤ .001). CONCLUSIONS: Our findings add to the growing body of evidence supporting universal rectal screening in high-risk women such as those undergoing pelvic exams at STI clinics.

The effect of first-wave COVID-19 restrictions on HCV testing in Alberta, Canada: A trend analysis from 2019 to 2022.

Background: Prior to the COVID-19 pandemic, Alberta was on track to meet national HCV elimination targets by 2030. However, it is unclear how the pandemic has affected progress. Here, we aim to assess the impact of first-wave COVID-19 restrictions on Alberta HCV testing trends. Methods: HCV testing information was extracted from the provincial public health laboratory from 2019 to 2022. HCV antibody and RNA testing were categorized into (1) number ordered, (2) number positive, and (3) percent positivity, and stratified by HCV history status. Testing trends were evaluated across locations engaging high-risk individuals and priority demographics. An interrupted time-series analysis was used to identify average monthly testing rates before, during, and after first-wave COVID-19 restrictions. Results: Overall, HCV testing trends were significantly affected by COVID-19 restrictions in April 2020. Average monthly rates decreased by 98.39 antibody tests ordered per 100,000 among individuals without an HCV history and by 1.78 RNA tests ordered per 100,000 among those with an HCV history. While antibody and RNA testing trends started to rebound in the follow-up period relative to pre-restriction period, testing levels in the follow-up period remained below pre-restriction levels for all groups, except for addiction/recovery centres and emergency room/acute care facilities, which increased. Conclusions: If rates are to return to pre-restriction levels and elimination goals are to be met, more work is needed to engage individuals in HCV testing. As antibody testing rates are rebounding, reengaging those with a history of HCV for viral load monitoring and treatment should be prioritized.

Prevalence of syphilis coinfection in hepatitis C virus positive prenatal patients from Alberta during a pilot routine screening program.

BACKGROUND: Alberta routinely screens pregnant patients for select communicable diseases. Hepatitis C virus (HCV) was added to the prenatal screening panel as part of a provincial pilot program in February 2020. This retrospective cross-sectional study aimed to characterize the prevalence of syphilis coinfections in prenatal patients infected with HCV following implementation of the pilot program.METHODS: Routine prenatal HCV and syphilis testing data were extracted from the Public Health Laboratory Information System over a 21-month period. HCV positivity was defined as HCV enzyme immunoassay (EIA) reactive with detected HCV ribonucleic acid (RNA) following molecular confirmation, and positive results were examined for syphilis coinfections. All patients reactive on a syphilis EIA and confirmatory Treponema pallidum particle agglutination (TPPA) or follow-up rapid plasma reagin (RPR) test were considered positive for syphilis. Descriptive statistics for coinfected patients were analyzed. RESULTS: Eighty-seven prenatal patients were identified to be positive for HCV. Of those, 19 (21.8%) were reactive on the syphilis EIA and 17 (19.5%) had confirmed infections with the TPPA or RPR tests. For HCV/syphilis coinfected patients, the majority resided in metropolitan regions (64.6%), were from the lowest income quintile neighbourhoods (47.1%) and had previously tested positive for HCV (82.4%) and syphilis (64.6%) at the public health laboratory. CONCLUSIONS: The prevalence of syphilis coinfections in prenatal patients infected with HCV is high in Alberta. HCV/syphilis coinfection prevalence should be further investigated in other jurisdictions and prenatal cohorts to better understand testing and treatment options for prevention of congenital transmission.

Use of quantitative HIV RNA detection for early diagnosis of HIV infection in infants and acute HIV infections in Alberta, Canada.

Quantitative HIV RNA viral load (QVL) assays (Roche Diagnostics) were sensitive and specific when used to diagnose HIV infection in (i) HIV-exposed infants (sensitivity of 100% [63.1 to 100%] and specificity of 100% [97.9 to 100%]) and (ii) suspected acute HIV infection patients with a negative/indeterminate Western blot (sensitivity of 97.6% [91.6 to 99.7%] and specificity of 100% [96.1 to 100%]). No false-positive QVL results were identified.

Seropositivity to SARS-CoV-2 in Alberta, Canada in a post-vaccination period (March 2021-July 2021).

BACKGROUND: The COVID-19 pandemic has necessitated the need to rapidly make public health decisions. We systematically evaluated SARS-CoV-2 seropositivity to understand local COVID-19 epidemiology and support evidence-based public health decision making. METHODS: Residual blood samples were collected for SARS-CoV-2 receptor binding domain (RBD) IgG testing over a 1-5 day period monthly from 26 February 2021-9 July 2021 from six clinical laboratories across the province of Alberta, Canada. Monthly crude and adjusted (for age and gender) seropositivity were calculated. Results were linked to provincial administrative, laboratory, and vaccine databases. RESULTS: 60,632 individual blood samples were tested. Vaccination data were available for 98.8% of samples. Adjusted RBD IgG positivity rose from 11.9% (95% confidence interval [CI] 11.9-12.0%) in March 2021 to 70.2% (95% CI 70.2-70.3%) in July 2021 (p < .0001). Seropositivity rose from 9.4% (95% CI 9.3-9.4%) in March 2021 to 20.2% (95% CI 20.1-20.2%) in July 2021 in unvaccinated Albertans. Unvaccinated seropositive individuals were from geographic areas with significantly (p < .001) lower median household income, lower proportion of married/common-law relationships, larger average household size and higher proportions of visible minorities compared to seronegative unvaccinated individuals. In July 2021, the age groups with the lowest and highest seropositivity in unvaccinated Albertans were those ≥80 years (12.0%, 95% CI 5.3-18.6%) and 20-29 years (24.2%, 95% CI 19.6-28.8%), respectively. Of seropositive unvaccinated individuals, 50.2% (95% CI 45.9-54.5%) had no record of prior SARS-CoV-2 molecular testing. CONCLUSIONS: Longitudinal surveillance of SARS-CoV-2 seropositivity with data linkage is valuable for decision-making during the pandemic.

Pregnancy and neonatal outcomes of women with reactive syphilis serology in Alberta, 2002 to 2006.

OBJECTIVES: To describe the maternal characteristics, diagnosis, and pregnancy, and the neonatal outcomes of pregnant women with reactive syphilis serology in a Canadian cohort. METHODS: We conducted a retrospective chart review of pregnant women in Alberta with reactive syphilis serology between 2002 and 2006. Clinical staging of syphilis in mothers and infants was determined using provincial and national surveillance criteria. RESULTS: Seventy-five pregnancies met the inclusion criteria. Thirty women were adequately treated pre-conception, 20 women had infectious syphilis (10 primary, 5 secondary, 5 early latent), 24 had late latent syphilis, and one had disease of unknown stage. Seven infants with congenital syphilis and one infant with presumed congenital syphilis were born to women with primary (n = 4), secondary (n = 2), early latent (n = 1), and unknown stage (n = 1) syphilis. Treatment was provided prior to delivery in one woman; five women did not access prenatal care. Four infants had long-term sequelae. CONCLUSION: All infants with congenital syphilis were born to women with infectious syphilis who had limited prenatal care. Initiatives to reach women at high risk are required to decrease the incidence of congenital syphilis.

A low-cost initiative to reduce duplicate hepatitis B virus serological testing.

BACKGROUND: Currently, multiple clinical laboratories provide serological testing for hepatitis B virus (HBV) in Alberta, Canada. Concerns were raised regarding single serology specimens having duplicate testing performed during the specimen referral process from one laboratory to another. In an attempt to reduce duplicate testing for anti-HBs and HBsAg markers, we implemented a stamp on paper requisitions to identify if testing had already been performed on referred specimens. We aimed to determine the number of duplicate tests and cost of duplicate testing pre- and post-stamp implementation. STUDY DESIGN: The requisition stamp was implemented between May and August 2016. HBV serology testing results from two clinical laboratories between January 01, 2015 and December 31, 2017 (n â€‹= â€‹803,637) were examined. The number of tests performed on the same individual within a 3-day window was identified and the associated costs were determined. RESULTS: After stamp implementation, duplicated HBsAg and anti-HBs tests decreased from 20.8% (n â€‹= â€‹28,545) and 18.4% (n â€‹= â€‹20,151) to 3.7% (n â€‹= â€‹4,604) and 2.5% (n â€‹= â€‹2,593), respectively. This represented an estimated annual savings of $86,427 and $82,522 CAD in supply costs for HBsAg and anti-HBs tests, respectively. CONCLUSIONS: The requisition stamp initiative was effective in reducing the number of duplicate tests performed between two laboratory sites. This low-cost intervention could be applied to other testing situations, including other highly duplicated serological markers, which may have broad reaching cost-saving effects for laboratory testing.

Distribution of HPV genotypes among women with abnormal cytology results in Alberta, Canada.

Background: Persistent infection with a subset of human papillomavirus (HPV) genotypes can cause abnormal cytology and invasive cervical cancer. This study examines the circulating HPV genotype strains in a local population of the province of Alberta (a largely unvaccinated population) to establish baseline frequency of vaccine and non-vaccine genotypes causing abnormal cervical cytology. Method: Remnant liquid-based cytology specimens from the Alberta Cervical Cancer Screening Program (March 2014-January 2016) were examined. Only specimens from women who had a cytology grading of atypical squamous cells of undetermined significance or higher were included. HPV genotype was determined for all samples, and results were stratified by demographics and cytology results. Results: Forty-four unique HPV genotypes were identified from 4,794 samples. Of the 4,241 samples with a genotype identified, the most common genotypes were HPV 16, 18, 31, and 51, with 1,599 (37.7%), 441 (12.2%), 329 (7.8%), and 354 (8.4%), respectively. HPV9 vaccine genotypes made up 73.2% of these genotyped samples. Compared with specimens in which HPV9 vaccine genotypes were not detected, those with a genotype covered by the HPV9 vaccine were from younger women (33 [interquartile range {IQR] 28 to 42] y versus 40 [IQR 32 to 51] y; p < 0.00001). Conclusions: The baseline distribution of HPV genotypes in this largely unvaccinated population indicates that the HPV9 vaccine provides good protection from high-risk HPV infections. Determining the frequency of genotypes causing abnormal cytology in this population post-vaccine implementation will be important to assess efficacy of vaccination and monitor for any potential genotype replacement.

Historique: L'infection persistante par un sous-groupe de génotypes du virus du papillome humain (VPH) peut être responsable d'une cytologie anormale et d'un cancer invasif du col de l'utérus. La présente étude porte sur les souches du génotype du VPH en circulation dans une population locale de la province de l'Alberta (largement non vaccinée) pour établir la fréquence de base des génotypes vaccinaux et non vaccinaux responsables de cytologies du col de l'utérus anormales. Méthodologie: Les chercheurs ont examiné les résidus de prélèvement de cytologie en milieu liquide du programme albertain de dépistage du cancer du col de l'utérus (de mars 2014 à janvier 2016). Seuls les prélèvements de femmes dont la cytologie était classée d'après la présence de cellules squameuses (ou malpighiennes) atypiques à caractère non déterminé ou plus graves ont été retenus. Les chercheurs ont déterminé le génotype du VPH de tous les prélèvements et stratifié les résultats selon les résultats démographiques et cytologiques. Résultats: Les chercheurs ont retenu 44 génotypes uniques du VPH à partir de 4 794 prélèvements. Les VPH 16, 18, 31 et 51 étaient les principaux génotypes observés, correspondant à 1 599 (37,7 %), 441 (12,2 %), 329 (7,8 %) et 354 (8,4 %) cas, respectivement. Les génotypes du vaccin contre le VPH9 représentaient 73,2 % des prélèvements. Par rapport aux prélèvements dans lesquels les génotypes du vaccin contre le VPH9 n'avaient pas été décelés, ceux dont le génotype était couvert par le vaccin contre le VPH9 provenaient de femmes plus jeunes (33 ans [plage interquartile {PIQ} de 28 à 42] par rapport à 40 ans chez les autres [PIQ de 32 à 51]; p < 0,00001). Conclusion: Selon la distribution de référence des génotypes du VPH dans cette population largement non vaccinée, le vaccin contre le VPH9 assure une bonne protection contre les infections à VPH à haut risque. Il sera important de déterminer la fréquence des génotypes responsables d'une cytologie anormale dans cette population après l'adoption du vaccin pour en évaluer l'efficacité et surveiller le remplacement potentiel des génotypes.

Pre-Vaccine Positivity of SARS-CoV-2 Antibodies in Alberta, Canada during the First Two Waves of the COVID-19 Pandemic.

We systematically evaluated SARS-CoV-2 IgG positivity in a provincial cohort to understand the local epidemiology of COVID-19 and support evidence-based public health decisions. Residual blood samples were collected for serology testing over 5-day periods monthly from June 2020 to January 2021 from six clinical laboratories across the province of Alberta, Canada. A total of 93,993 individual patient samples were tested with a SARS-CoV-2 nucleocapsid antibody assay with positives confirmed using a spike antibody assay. Population-adjusted SARS-CoV-2 IgG seropositivity was 0.92% (95% confidence interval [CI]: 0.91 to 0.93%) shortly after the first COVID-19 wave in June 2020, increasing to 4.63% (95% CI: 4.61 to 4.65%) amid the second wave in January 2021. There was no significant difference in seropositivity between males and females (1.39% versus 1.27%; P = 0.11). Ages with highest seropositivity were 0 to 9 years (2.71%, 95% CI: 1.64 to 3.78%) followed by 20 to 29 years (1.58%, 95% CI: 1.12 to 2.04%), with the lowest rates seen in those aged 70 to 79 (0.79%, 95% CI: 0.65 to 0.93%) and >80 (0.78%, 95% CI: 0.60 to 0.97%). Compared to the seronegative group, seropositive patients inhabited geographic areas with lower household income ($87,500 versus $97,500; P < 0.001), larger household sizes, and higher proportions of people with education levels of secondary school or lower, as well as immigrants and visible minority groups (all P < 0.05). A total of 53.7% of seropositive individuals were potentially undetected cases with no prior positive COVID-19 nucleic acid test (NAAT). Antibodies were detectable in some patients up to 9 months post positive NAAT result. This seroprevalence study will continue to inform public health decisions by identifying at-risk demographics and geographical areas. IMPORTANCE Using SARS-CoV-2 serology testing, we assessed the proportion of people in Alberta, Canada (population 4.4 million) positive for COVID-19 antibodies, indicating previous infection, during the first two waves of the COVID-19 pandemic (prior to vaccination programs). Linking these results with sociodemographic population data provides valuable information as to which groups of the population are more likely to have been infected with the SARS-CoV-2 virus to help facilitate public health decision-making and interventions. We also compared seropositivity data with previous COVID-19 molecular testing results. Absence of antibody and molecular testing were highly correlated (95% negative concordance). Positive antibody correlation with a previous positive molecular test was low, suggesting the possibility of mild/asymptomatic infection or other reasons leading individuals from seeking medical attention. Our data highlight that the true estimate of population prevalence of COVID-19 is likely best informed by combining data from both serology and molecular testing.

Seroprevalence and correlates of HIV and HCV among injecting drug users in Edmonton, Alberta.

BACKGROUND: Injection drug users (IDUs) are at risk for acquiring human immunodefiency virus (HIV) and hepatitis C virus (HCV) via parenteral and sexual transmission. We determined the seroprevalence and correlates of HIV and HCV for IDUs recruited in Edmonton, Alberta. METHODS: Edmonton was one site of a multi-site, national survey (I-Track Study). From April to June 2005, IDUs were recruited and administered a questionnaire collecting information on demographics, drug use, sexual behaviours, and HIV/HCV testing behaviours. Finger-prick blood samples were collected for serology testing. Seroprevalence of HIV and HCV was determined and correlates of infection were assessed using logistic regression. RESULTS: Of 275 IDUs, 68% were male, the median age was 38 years and 70.6% were Aboriginal. HIV prevalence was 23.9%, HCV prevalence was 66.1% and HIV/HCV co-infection was 22.8%. Cocaine (36.9%) was reported to be the drug injected most often in the previous six months. Correlates for HIV were sex trade (OR 2.9, 95% CI 1.0-8.3) for women, and older age (OR 1.1, 95% CI 1.0-1.2) and needle exchange program (NEP) use (OR 5.7, 95% CI 1.3-23.7) for men. For women, having a casual sex partner was protective for HCV (OR 0.28, 95% CI 0.10-0.78). Independent correlates for HCV among males included age (AOR 1.2, 95% CI 1.1-1.3) and younger age of first injection (AOR 0.92, 95% CI 0.87-0.96). CONCLUSION: The high HIV and HCV prevalence found in this study among IDUs in Edmonton highlights the complex needs of the IDU community and the continued need for targeted programming.

Examination of a Canadian provincial prenatal HIV screening program: 2010 to 2014.

OBJECTIVES: Universal prenatal screening in the Canadian province of Alberta employs an 'opt-out' HIV screening strategy. We examined all women giving birth in the province and determined the frequency and characteristics of women having and not having HIV screening. METHODS: All livebirths in Alberta from January 1, 2010 to December 31, 2014 were compiled from the Vital Statistics database and linked to HIV screening data to determine maternal demographic and prenatal care characteristics. Correlates associated with prenatal HIV screening, opting out of HIV screening, and not having any prenatal communicable disease screening were determined by multivariable statistics. RESULTS: Of the 256,280 live births, 94.2% had prenatal HIV screening, 1.9% declined prenatal HIV screening, and 3.9% had no record of any prenatal communicable disease testing. Compared with those who had HIV screening, those who opted out of prenatal HIV screening were more likely to be over 40 years of age (adjusted odds ratio (AOR), 2.83 [2.12-3.78]) and less likely to be single (AOR, 0.67 [0.62-0.73]) and First Nations (AOR, 0.67 [0.56-0.82]). Those who received no prenatal communicable disease screening were less likely to be over 40 years of age (AOR, 0.81 [0.69-0.95]) and more likely to be single (AOR, 1.27 [1.21-1.33]) and have received no prenatal care (AOR, 6.78 [6.40-7.19]). Both the HIV decliners and prenatal non-testers were more likely to have used a midwife (AOR, 4.52 [3.83-5.35] and AOR, 2.44 [2.03-2.92], respectively). CONCLUSION: Demographic and prenatal care characteristics differ by a pregnant woman's prenatal screening status. Policies to improve HIV screening coverage should take these variations into account.

HIV seroprevalence among women opting out of prenatal HIV screening in Alberta, Canada: 2002-2004.

Alberta, Canada, uses an "opt-out" strategy for prenatal HIV testing. We examined demographic characteristics of and HIV seroprevalence among women opting out. The proportion of total specimens that were from women who opted out decreased from 4.3% in 2002 to 3.6% in 2004 (P<.001), and HIV seroprevalence among these specimens was 0.07%, which was 3.3 times higher than the HIV seroprevalence among specimens from women who opted in. Women opting out may have a higher HIV infection risk.

Outcomes from a Canadian public health prenatal screening program for hepatitis B: 1997-2004.

BACKGROUND: Without appropriate prophylaxis, the rate of vertical transmission of hepatitis B virus (HBV) can be as high as 95%. Alberta's provincial prenatal program screens all pregnant women for HBV, and provides prophylaxis to infants born to HBV-infected women. Canadian data on the outcomes of such programs are limited. METHODS: We conducted a retrospective review of data from pregnant Albertan women who were Hepatitis B Surface Antigen (HBsAg) positive from 1997-2004. We describe the frequency of hepatitis B immunoglobulin (HBIG) and vaccine administration, follow-up serology and pregnancy outcomes. RESULTS: In total, 1,485 HBsAg-positive pregnant women were identified; an average of 186 women annually (range: 125-216). Of the 980 infants eligible to have completed prophylaxis and serological follow-up, 82.0% were appropriately immunized and serologically tested, 11.3% had complete immunization but no serology testing and 6.6% were incompletely immunized. Of infants with complete immunization and follow-up, 3.7% failed to mount an immune response and 2.1% were infected. CONCLUSION: A high proportion of infants born to carrier mothers are receiving appropriate post-natal prophylaxis in Alberta. Future research should examine maternal factors that may increase the vertical transmission of HBV.