Dried blood spot samples have comparable diagnostic accuracy to serum collected by venipuncture when tested by an electrochemiluminescent assay for antibodies and should be considered to reliably detect seropositivity following SARS-CoV-2 infection and/or vaccination.

Background: Investigating antibody titers in individuals who have been both naturally infected with SARS-CoV-2 and vaccinated can provide insight into antibody dynamics and correlates of protection over time. Methods: Human coronavirus (HCoV) IgG antibodies were measured longitudinally in a prospective cohort of qPCR-confirmed, COVID-19 recovered individuals (k = 57) in British Columbia pre- and post-vaccination. SARS-CoV-2 and endemic HCoV antibodies were measured in serum collected between Nov. 2020 and Sept. 2021 (n = 341). Primary analysis used a linear mixed-effects model to understand the effect of single dose vaccination on antibody concentrations adjusting for biological sex, age, time from infection and vaccination. Secondary analysis investigated the cumulative incidence of high SARS-CoV-2 anti-spike IgG seroreactivity equal to or greater than 5.5 log10 AU/mL up to 105 days post-vaccination. No re-infections were detected in vaccinated participants, post-vaccination by qPCR performed on self-collected nasopharyngeal specimens. Results: Bivariate analysis (complete data for 42 participants, 270 samples over 472 days) found SARS-CoV-2 spike and RBD antibodies increased 14–56 days post-vaccination (p < 0.001) and vaccination prevented waning (regression coefficient, B = 1.66 [95%CI: 1.45–3.46]); while decline of nucleocapsid antibodies over time was observed (regression coefficient, B = −0.24 [95%CI: −1.2-(−0.12)]). A positive association was found between COVID-19 vaccination and endemic human β-coronavirus IgG titer 14–56 days post vaccination (OC43, p = 0.02 & HKU1, p = 0.02). On average, SARS-CoV-2 anti-spike IgG concentration increased in participants who received one vaccine dose by 2.06 log10 AU/mL (95%CI: 1.45–3.46) adjusting for age, biological sex, and time since infection. Cumulative incidence of high SARS-CoV-2 spike antibodies (>5.5 log10 AU/mL) was 83% greater in vaccinated compared to unvaccinated individuals. Conclusions: Our study confirms that vaccination post-SARS-CoV-2 infection provides multiple benefits, such as increasing anti-spike IgG titers and preventing decay up to 85 days post-vaccination.

Wastewater surveillance is a valuable and noninvasive way to detect, monitor and rule out viral pathogen transmission at the population level. Drawing on lessons learned from severe acute respiratory virus two (SARS-CoV-2), monkeypox virus, norovirus and influenza A viruses, we outline six key considerations for designing or refining a wastewater surveillance program for a viral pathogen: pathogen suitability, surveillance objective, sampling strategy, molecular assays, data transformation, and analysis. Together, these components form an interdisciplinary “wastewater toolkit” that supports methodological rigor, adaptability, and comparability across settings. By providing a structured yet flexible framework that accommodates technical variation and contextual differences, this toolkit enhances preparedness and enables the rapid establishment or optimization of wastewater surveillance systems. Gaps and inefficiencies in disease surveillance can lead to inaccurate intelligence and inadequate or inappropriate public health responses, a systematic wastewater surveillance framework is essential to generate reliable indicators of viral transmission and inform timely, evidence-based decision-making for known and emerging pathogens.

Nucleic acid amplification tests, like real-time polymerase chain reaction, are widely used for pathogen detection; however, their interpretation rarely accounts for sampling variability. Instead, cycle threshold values are often categorized reducing precision. We describe how pathogen cycle threshold values can be normalized to endogenous host gene expression to correct for sampling variability and compare the validity of this approach to standardization with a standard curve. Normalization serves as a valid alternative to standardization, does not require making a standard curve, increases precision, accounts for sampling variability, and can be easily applied to large clinical or surveillance datasets for informative interpretation.

The COVID-19 pandemic has highlighted the need for generic reagents and flexible systems in diagnostic testing. Magnetic bead-based nucleic acid extraction protocols using 96-well plates on open liquid handlers are readily amenable to meet this need. Here, one such approach is rigorously optimized to minimize cross-well contamination while maintaining sensitivity. Article Summary A scalable, non-proprietary, magnetic bead-based automated nucleic acid extraction protocol optimised for minimum cross-well contamination