Sentinel Surveillance System Implementation and Evaluation for SARS-CoV-2 Genomic Data, Washington, USA, 2020-2021.

Genomic data provides useful information for public health practice, particularly when combined with epidemiologic data. However, sampling bias is a concern because inferences from nonrandom data can be misleading. In March 2021, the Washington State Department of Health, USA, partnered with submitting and sequencing laboratories to establish sentinel surveillance for SARS-CoV-2 genomic data. We analyzed available genomic and epidemiologic data during presentinel and sentinel periods to assess representativeness and timeliness of availability. Genomic data during the presentinel period was largely unrepresentative of all COVID-19 cases. Data available during the sentinel period improved representativeness for age, death from COVID-19, outbreak association, long-term care facility-affiliated status, and geographic coverage; timeliness of data availability and captured viral diversity also improved. Hospitalized cases were underrepresented, indicating a need to increase inpatient sampling. Our analysis emphasizes the need to understand and quantify sampling bias in phylogenetic studies and continue evaluation and improvement of public health surveillance systems.

Dose-response assessment for impaired memory from chronic exposure to domoic acid among native American consumers of razor clams.

Domoic acid (DA) is a marine neurotoxin that accumulates in filtering shellfish during harmful algal blooms. A health protection limit of 20 ppm DA in razor clams (RC) has been set based principally upon an episode of acute DA toxicity in humans that included Amnesic Shellfish Poisoning among survivors. The objective of this study was to determine the dose-response relationship between estimated DA exposure through RC consumption and memory loss in Washington state Native Americans from 2005 to 2015. Results from total learning recall (TLR) memory scores were compared before and after the highest DA exposures. A decrease in TLR was related to DA dose (p < 0.01) regardless whether the effect was assumed to be transient or lasting, and whether the dose was expressed as an average daily dose or an average dose per meal. Benchmark dose modeling identified BMDL10 values of 167 ng/kg-day and 2740 ng/kg-meal assuming a transient effect, and 196 ng/kg-day and 2980 ng/kg-meal assuming no recovery of function occurs. These DA dose thresholds for a measurable memory function reduction observed in this study of clam consumers are well below the safe acute dose underpinning the current regulatory DA limit of 20 ppm (ca. 60 µg/kg).

COVID-19 Contact Tracing Outcomes in Washington State, August and October 2020.

Introduction: Case investigation and contact tracing are important tools to limit the spread of SARS-CoV-2, particularly when implemented efficiently. Our objective was to evaluate participation in and timeliness of COVID-19 contact tracing and whether these measures changed over time. Methods: We retrospectively assessed COVID-19 case investigation and contact tracing surveillance data from the Washington State centralized program for August 1-31, 2020 and October 1-31, 2020. We combined SARS-CoV-2 testing reports with contact tracing data to compare completeness, reporting of contacts, and program timeliness. Results: For August and October respectively, 4,600 (of 12,521) and 2,166 (of 16,269) individuals with COVID-19 were referred to the state program for case investigation. Investigators called 100% of referred individuals; 65% (August) and 76% (October) were interviewed. Of individuals interviewed, 33% reported contacts in August and 45% in October, with only mild variation by age, sex, race/ethnicity, and urbanicity. In August, 992 individuals with COVID-19 reported a total of 2,584 contacts (mean, 2.6), and in October, 739 individuals reported 2,218 contacts (mean, 3.0). Among contacts, 86% and 78% participated in interviews for August and October. The median time elapsed from specimen collection to contact interview was 4 days in August and 3 days in October, and from symptom onset to contact interview was 7 days in August and 6 days in October. Conclusions: While contact tracing improved with time, the proportion of individuals disclosing contacts remained below 50% and differed minimally by demographic characteristics. The longest time interval occurred between symptom onset and test result notification. Improving elicitation of contacts and timeliness of contact tracing may further decrease SARS-CoV-2 transmission.