Sentinel Surveillance

On March 13, 2020, the United States declared a national emergency to combat coronavirus disease 2019 (COVID-19). As the number of persons hospitalized with COVID-19 increased, early reports from Austria (1), Hong Kong (2), Italy (3), and California (4) suggested sharp drops in the numbers of persons seeking emergency medical care for other reasons. To quantify the effect of COVID-19 on U.S. emergency department (ED) visits, CDC compared the volume of ED visits during four weeks early in the pandemic March 29-April 25, 2020 (weeks 14 to 17; the early pandemic period) to that during March 31-April 27, 2019 (the comparison period). During the early pandemic period, the total number of U.S. ED visits was 42% lower than during the same period a year earlier, with the largest declines in visits in persons aged ≤14 years, females, and the Northeast region. Health messages that reinforce the importance of immediately seeking care for symptoms of serious conditions, such as myocardial infarction, are needed. To minimize SARS-CoV-2, the virus that causes COVID-19, transmission risk and address public concerns about visiting the ED during the pandemic, CDC recommends continued use of virtual visits and triage help lines and adherence to CDC infection control guidance.

From January 21 through February 23, 2020, public health agencies detected 14 U.S. cases of coronavirus disease 2019 (COVID-19), all related to travel from China (1,2). The first nontravel-related U.S. case was confirmed on February 26 in a California resident who had become ill on February 13 (3). Two days later, on February 28, a second nontravel-related case was confirmed in the state of Washington (4,5). Examination of four lines of evidence provides insight into the timing of introduction and early transmission of SARS-CoV-2, the virus that causes COVID-19, into the United States before the detection of these two cases. First, syndromic surveillance based on emergency department records from counties affected early by the pandemic did not show an increase in visits for COVID-19-like illness before February 28. Second, retrospective SARS-CoV-2 testing of approximately 11,000 respiratory specimens from several U.S. locations beginning January 1 identified no positive results before February 20. Third, analysis of viral RNA sequences from early cases suggested that a single lineage of virus imported directly or indirectly from China began circulating in the United States between January 18 and February 9, followed by several SARS-CoV-2 importations from Europe. Finally, the occurrence of three cases, one in a California resident who died on February 6, a second in another resident of the same county who died February 17, and a third in an unidentified passenger or crew member aboard a Pacific cruise ship that left San Francisco on February 11, confirms cryptic circulation of the virus by early February. These data indicate that sustained, community transmission had begun before detection of the first two nontravel-related U.S. cases, likely resulting from the importation of a single lineage of virus from China in late January or early February, followed by several importations from Europe. The widespread emergence of COVID-19 throughout the United States after February highlights the importance of robust public health systems to respond rapidly to emerging infectious threats.

Between weeks 40 2020 and 8 2021, the World Health Organization European Region experienced a 99.8% reduction in sentinel influenza virus positive detections (33/25,606 tested; 0.1%) relative to an average of 14,966/39,407 (38.0%; p < 0.001) over the same time in the previous six seasons. COVID-19 pandemic public health and physical distancing measures may have extinguished the 2020/21 European seasonal influenza epidemic with just a few sporadic detections of all viral subtypes. This might possibly continue during the remainder of the influenza season.

ImportanceCurrent colorectal surveillance guidelines emphasize adenoma characteristics but overlook temporal, racial, and sex-based heterogeneity in recurrence risk, a gap that limits equitable and personalized care.ObjectiveTo evaluate the associations of demographic factors, obesity, and adenoma features with recurrence risk over time in a large longitudinal surveillance cohort.Design, setting, and participantsThis retrospective cohort study included adults who underwent their first colonoscopic polypectomy between January 1990 and July 2024 at a tertiary medical center.ExposuresDemographic variables included race and ethnicity, sex, obesity (body mass index >30), family history of colorectal cancer (CRC) or polyps, and age at adenoma onset (Main outcomes and measuresThe primary outcome was recurrence-free survival, defined as time from initial polypectomy to histologically confirmed recurrence. Time-varying coefficient Cox models were fitted to handle the nonconstant associations of exposure over the follow-up time. The follow-up time was categorized into 3 periods (less than 5 years, 5 to 10 years, and 10 or more years). The heterogeneity of exposure associations across the 3 follow-up periods was assessed with likelihood ratio tests.ResultsAmong 59 667 patients (mean [SD] age, 60 years [11.2]; 29 401 [49.3%] female; 1007 [1.7%] Asian and Pacific Islander, 646 [1.1%] Hispanic, 5972 [10.0%] non-Hispanic Black, and 52 042 [87.2%] non-Hispanic White; median [IQR] follow-up, 4 [1-9] years), 17 596 (29.5%) experienced overall recurrence within 5 years. High-grade dysplasia demonstrated the largest early phase association (adjusted hazard ratio [aHR], 4.00; 95% CI, 3.56-4.50) with complete midterm and late attenuation, while villous histology exhibited biphasic patterns with early elevation (aHR, 2.89; 95% CI, 2.63-3.18) and late-phase (>10 years) reemergence (aHR, 2.71; 95% CI, 2.15-3.41). Obesity conferred persistent risk across all surveillance intervals (early: aHR, 1.16; 95% CI, 1.11-1.21; late: aHR, 1.22; 95% CI, 1.09-1.35). Female patients with high-risk adenomas exhibited marked late-term (>10 years) elevation exceeding male patients (female patients: aHR, 1.73; 95% CI, 1.43-2.08 vs male patients: aHR, 1.29; 95% CI, 1.06-1.58).Conclusions and relevanceBoth histopathologic features and demographic factors demonstrated distinct time-dependent patterns in adenoma recurrence, underscoring the need for surveillance strategies that account for temporal variation and population-specific risk profiles.