Publications by authors named "Krajden M"

Unlabelled: The objective of the study was to ascertain an optimal diagnostic strategy using population-level laboratory data comparing the performance of serology against urea breath test (UBT). diagnostic test results for serology and UBT from two laboratories over a 12-year period (2006-20017) were extracted, linked, and analyzed. A subset of this population underwent both methods of testing within days of each other, enabling a direct comparison of the two methods.

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Background: We evaluated the association of hepatitis B virus (HBV) treatment with all-cause, and liver-related mortality among individuals with HBV and cirrhosis in British Columbia (BC), Canada.

Methods: This analysis included people diagnosed with HBV and had cirrhosis in the BC Hepatitis Testers Cohort, including data on all individuals diagnosed with HBV from 1990 to 2015 in BC and integrated with healthcare administrative data. We followed people with cirrhosis from the first cirrhosis diagnosis date until death or December 31, 2020.

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Article Synopsis
  • In Canada, each province and territory handles their own health data, which made it tricky to share information during the COVID-19 pandemic.
  • There were 11 different surveys done to test how many people had antibodies from the virus, but they each used different methods, making it hard to compare results across regions.
  • To do better in the future, Canada needs a strong and flexible system for tracking health data that can quickly adjust to new situations and work together across different areas.
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Objectives: To measure and evaluate the impact of receiving severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccines in pregnancy on immunoglobulin G (IgG) and immunoglobulin A (IgA) titres in maternal and infant samples.

Design: Prospective cohort study.

Setting: Tertiary obstetric centre.

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We assessed the impact of the COVID-19 pandemic on hepatocellular carcinoma (HCC) surveillance among individuals with HCV diagnosed with cirrhosis in British Columbia (BC), Canada. We used data from the British Columbia Hepatitis Testers Cohort (BC-HTC), including all individuals in the province tested for or diagnosed with HCV from 1 January 1990 to 31 December 2015, to assess HCC surveillance. To analyse the impact of the pandemic on HCC surveillance, we used pre-policy (January 2018 to February 2020) and post-policy (March to December 2020) periods.

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  • Chronic/latent viral infections, particularly in people living with HIV (PLWH), can accelerate immunological aging, and the study investigated their impact on leukocyte telomere length (LTL).
  • The research involved 377 participants across various age groups, genders, and HIV statuses, finding that PLWH and older females tend to harbor more chronic/latent viruses, which is linked to shorter LTL.
  • Ultimately, the study indicates that persistent viral infections may contribute to immunological aging in PLWH and highlights the need to explore potential health issues associated with this later in life.
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We investigated the impacts of the COVID-19 pandemic on hepatitis C (HCV) treatment initiation, including by birth cohort and injection drug use status, in British Columbia (BC), Canada. Using population data from the BC COVID-19 Cohort, we conducted interrupted time series analyses, estimating changes in HCV treatment initiation following the introduction of pandemic-related policies in March 2020. The study included a pre-policy period (April 2018 to March 2020) and three follow-up periods (April to December 2020, January to December 2021, and January to December 2022).

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  • - This study analyzes long-term risks of cervical precancer after negative HPV screenings to refine cervical cancer screening intervals and reduce unnecessary treatments.
  • - The research followed over 12,000 participants in British Columbia from 2008 to 2022, comparing the risk of cervical precancer (CIN2+) between HPV screening and traditional cytology results.
  • - Results showed low cumulative risks of CIN2+ in HPV cohorts after 8 years, which were similar to cytology cohorts after just 3 years, suggesting that HPV screening intervals could be safely extended beyond the current 5-year recommendation.
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  • The study evaluated immune responses to COVID-19 vaccines in adults aged 50 and older by measuring antibody levels and T-cell responses after a two-dose series.
  • Vaccinated individuals with mRNA/mRNA and ChAdOx1-S/mRNA regimens showed higher antibody responses compared to those receiving the ChAdOx1-S/ChAdOx1-S regimen, peaking one month after the second dose.
  • It suggests that both antibody concentration and avidity should be factored in when assessing COVID-19 vaccine protection.
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SARS-CoV-2 Omicron subvariants with increased transmissibility and immune evasion are spreading globally with alarming persistence. Whether the mutations and evolution of spike (S) Omicron subvariants alter the viral hijacking of human TMPRSS2 for viral entry remains to be elucidated. This is particularly important to investigate because of the large number and diversity of mutations of S Omicron subvariants reported since the emergence of BA.

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Background: In British Columbia (BC), self-collected saline gargle (SG) is the only alternative to health care provider (HCP)-collected nasopharyngeal (NP) swabs to detect SARS-CoV-2 in an outpatient setting by polymerase chain reaction (PCR). However, some individuals cannot perform a SG. Our study aimed to assess combined throat-bilateral nares (TN) swabbing as a swab-based alternative.

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Background: HCV infection is associated with mortality due to extrahepatic manifestations (EHM). Sustained virologic response (SVR) following direct-acting antiviral (DAA) therapy has been linked to decreased all-cause and liver-related mortality. However, evidence regarding the impact of DAA on EHM-related deaths is lacking.

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  • * Two phases of serosurveys involved 2,864 participants and found that 4.4% of all ages and 8.8% of unvaccinated young children tested positive for antibodies, with higher rates observed in South Asian participants.
  • * The findings highlight a need for better diagnostic strategies that consider age-specific factors in understanding COVID-19’s impact on pediatric populations.
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We sought to evaluate the rates and predictors of SARS-CoV-2 vaccination among members of a structurally-marginalized population of people who use drugs (PWUD) during a targeted, community-wide, vaccination campaign in Vancouver, Canada. Interviewer-administered data were collected from study participants between June 2021 and March 2022. Generalized estimating equation analysis was used to identify factors associated with SARS-CoV-2 vaccine uptake, ascertained through a province-wide vaccine registry.

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  • The study explored the use of Bayesian latent class models (BLCMs) to estimate the presence of anti-SARS-CoV-2 antibodies in blood donor samples, without relying on a definitive testing standard.
  • A total of 6,810 plasma samples from blood donors in Québec collected between May and July 2020 were tested with seven different serological assays, revealing a SARS-CoV-2 seroprevalence of 0.71%.
  • The research highlighted the variability in sensitivity among the assays used and emphasized that BLCMs can provide rapid updates on disease prevalence and assist public health efforts, especially when a gold standard test is unavailable.
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Background: Shifting from cytology to human papillomavirus (HPV)-based cervical cancer screening will initially increase colposcopy referrals. The anticipated impact on health systems has been raised as a concern for implementation. It is unclear if the higher rate of colposcopy referrals is sustained after initial HPV-based screens or reverts to new lower baselines due to earlier detection and treatment of precancer.

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Antivirals with broad coronavirus activity are important for treating high-risk individuals exposed to the constantly evolving SARS-CoV-2 variants of concern (VOCs) as well as emerging drug-resistant variants. We developed and characterized a novel class of active-site-directed 3-chymotrypsin-like protease (3CLpro) inhibitors (). Our lead direct-acting antiviral (DAA), , is a non-covalent, non-peptide with a dissociation constant of 170 nM against recombinant SARS-CoV-2 3CLpro.

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  • The study aimed to assess mortality rates in patients treated for hepatitis C using modern interferon-free, direct-acting antivirals and compare them to the general populace.
  • A total of 21,790 patients treated between 2014 and 2019 were analyzed, categorized by liver disease severity, with follow-up ending either at death or by the end of 2019.
  • Results showed a 7% mortality rate during follow-up, with deaths primarily from drug-related issues, liver failure, and liver cancer, and overall mortality rates significantly exceeded those of the general population, especially for patients with more advanced liver disease.
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Background: It was unknown if the effectiveness of COVID-19 vaccines could vary between regions.

Objective: To explore key differences in COVID-19 pandemics in British Columbia (BC) and Ontario (ON) and to investigate if the vaccine effectiveness (VE) among maintenance dialysis population could vary between these 2 provinces.

Study Design: Retrospective cohort.

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Background: Insufficient data on the rate and distribution of SARS-CoV-2 infection in Canada has presented a substantial challenge to the public health response to the COVID-19 pandemic. Our objective was to assess SARS-CoV-2 seroprevalence in a representative sample of pregnant people throughout Canada, across multiple time points over 2 years of the pandemic, to describe the seroprevalence and show the ability of this process to provide prevalence estimates.

Methods: This Canadian retrospective serological surveillance study used existing serological prenatal samples across 10 provinces over multiple time periods: Feb.

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The advent of next-generation sequencing (NGS) technologies has expanded our ability to detect and analyze microbial genomes and has yielded novel molecular approaches for infectious disease diagnostics. While several targeted multiplex PCR and NGS-based assays have been widely used in public health settings in recent years, these targeted approaches are limited in that they still rely on knowledge of a pathogen's genome, and an untargeted or unknown pathogen will not be detected. Recent public health crises have emphasized the need to prepare for a wide and rapid deployment of an agnostic diagnostic assay at the start of an outbreak to ensure an effective response to emerging viral pathogens.

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Background: The evolving proportion of the population considered immunologically naive versus primed for more efficient immune memory response to SARS-CoV-2 has implications for risk assessment. We sought to chronicle vaccine- and infection-induced seroprevalence across the first 7 waves of the COVID-19 pandemic in British Columbia, Canada.

Methods: During 8 cross-sectional serosurveys conducted between March 2020 and August 2022, we obtained anonymized residual sera from children and adults who attended an outpatient laboratory network in the Lower Mainland (Greater Vancouver and Fraser Valley).

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The COVID-19 pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), remains a global public health crisis. The reduced efficacy of therapeutic monoclonal antibodies against emerging SARS-CoV-2 variants of concern (VOCs), such as omicron BA.5 subvariants, has underlined the need to explore a novel spectrum of antivirals that are effective against existing and evolving SARS-CoV-2 VOCs.

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