The effectiveness of COVID-19 testing and contact tracing in a US city.

Although testing, contact tracing, and case isolation programs can mitigate COVID-19 transmission and allow the relaxation of social distancing measures, few countries worldwide have succeeded in scaling such efforts to levels that suppress spread. The efficacy of test-trace-isolate likely depends on the speed and extent of follow-up and the prevalence of SARS-CoV-2 in the community. Here, we use a granular model of COVID-19 transmission to estimate the public health impacts of test-trace-isolate programs across a range of programmatic and epidemiological scenarios, based on testing and contact tracing data collected on a university campus and surrounding community in Austin, TX, between October 1, 2020, and January 1, 2021. The median time between specimen collection from a symptomatic case and quarantine of a traced contact was 2 days (interquartile range [IQR]: 2 to 3) on campus and 5 days (IQR: 3 to 8) in the community. Assuming a reproduction number of 1.2, we found that detection of 40% of all symptomatic cases followed by isolation is expected to avert 39% (IQR: 30% to 45%) of COVID-19 cases. Contact tracing is expected to increase the cases averted to 53% (IQR: 42% to 58%) or 40% (32% to 47%), assuming the 2- and 5-day delays estimated on campus and in the community, respectively. In a tracing-accelerated scenario, in which 75% of contacts are notified the day after specimen collection, cases averted increase to 68% (IQR: 55% to 72%). An accelerated contact tracing program leveraging rapid testing and electronic reporting of test results can significantly curtail local COVID-19 transmission.

SARS-CoV-2 Disease Severity and Cycle Threshold Values in Children Infected during Pre-Delta, Delta, and Omicron Periods, Colorado, USA, 2021-2022.

In adults, viral load and disease severity can differ by SARS-CoV-2 variant, patterns less understood in children. We evaluated symptomatology, cycle threshold (Ct) values, and SARS-CoV-2 variants among 2,299 pediatric SARS-CoV-2 patients (0-21 years of age) in Colorado, USA, to determine whether children infected with Delta or Omicron had different symptom severity or Ct values than during earlier variants. Children infected during the Delta and Omicron periods had lower Ct values than those infected during pre-Delta, and children <1 year of age had lower Ct values than older children. Hospitalized symptomatic children had lower Ct values than asymptomatic patients. Compared with pre-Delta, more children infected during Delta and Omicron were symptomatic (75.4% pre-Delta, 95.3% Delta, 99.5% Omicron), admitted to intensive care (18.8% pre-Delta, 39.5% Delta, 22.9% Omicron), or received oxygen support (42.0% pre-Delta, 66.3% Delta, 62.3% Omicron). Our data reinforce the need to include children, especially younger children, in pathogen surveillance efforts.

Reaching Structurally Vulnerable Populations Using Low-Barrier COVID-19 Testing Clinics Co-Created with Community-Based Organizations.

BACKGROUND: The COVID-19 pandemic disproportionately affected people from structurally vulnerable communities. There was a need to improve COVID-19 testing in these communities to reduce viral spread and connect to treatment. OBJECTIVE: We created a partnership between an academic medical center and three community-based organizations (CBOs) to offer low-barrier COVID-19 walk-up testing clinics in Portland, Maine. Our objective was to examine whether the co-created testing clinics reached structurally vulnerable populations. DESIGN: The clinics offered COVID-19 rapid antigen tests three times a week outside CBO sites from January 2022 to May 2023. Clinic staff administered a brief survey on reason for testing and then instructed participants on how to self-swab. While staff processed the test, participants were invited to complete an additional survey about their demographics and testing perceptions. PARTICIPANTS: Adults seeking COVID-19 testing with specific outreach to people who are unhoused, immigrants, and low-income and/or uninsured. MAIN MEASURES: Number of tests conducted and result, reasons for testing, and testing perceptions. KEY RESULTS: Of 246 completed tests, 18 were positive for COVID-19 (7%). Participants sought testing for a variety of reasons, including symptoms (60%), close contact exposure (29%), and/or need for a negative test result to access services or an activity (33%). Overall, people primarily tested due to symptoms with only 7% testing due to close contact exposure alone. The clinics reached vulnerable populations. Among the 130 people completing the participant survey, 39% were unhoused, 22% spoke a language other than English at home, 23% were uninsured, and 46% earned less than $20,000 in 2019. Qualitative field notes captured key elements of clinics that influenced reach, and how this collaboration with CBOs helped build trust with our target populations. CONCLUSIONS: Providing low-barrier walk-up clinics partnering with trusted CBOs was observed to be helpful in reaching structurally vulnerable populations for COVID-19 testing.

COVID-19 outcomes in patients with multiple sclerosis: Understanding changes from 2020 to 2022.

BACKGROUND: Epidemiologic studies on coronavirus disease 2019 (COVID-19) in patients with multiple sclerosis (pwMS) have focused on the first waves of the pandemic until early 2021. OBJECTIVES: We aimed to extend these data from the onset of the pandemic to the global coverage by vaccination in summer 2022. METHODS: This retrospective, multicenter observational study analyzed COVISEP registry data on reported COVID-19 cases in pwMS between January 2020 and July 2022. Severe COVID-19 was defined as hospitalization or higher severity. RESULTS: Among 2584 pwMS with confirmed/highly suspected COVID-19, severe infection rates declined from 14.6% preomicron wave to 5.7% during omicron wave (p < 0.001). Multivariate analysis identified age (odds ratio (OR) = 1.43, 95% confidence interval (CI) = [1.25-1.64] per 10 years), male sex (OR = 2.01, 95% CI = [1.51-2.67]), obesity (OR = 2.36, 95% CI = [1.52-3.68]), cardiac comorbidities (OR = 2.36, 95% CI = [1.46-3.83]), higher Expanded Disability Status Scale (EDSS) scores (OR = 2.09, 95% CI = [1.43-3.06] for EDSS 3-5.5 and OR = 4.53, 95% CI = [3.04-6.75] for EDSS ⩾6), and anti-CD20 therapies (OR = 2.67, 95% CI = [1.85-3.87]) as risk factors for COVID-19 severity. Vaccinated individuals experienced less severe COVID-19, whether on (risk ratio (RR) = 0.64, 95% CI = [0.60-0.69]) or off (RR = 0.32, 95% CI = [0.30-0.33]) anti-CD20. DISCUSSION: In pwMS, consistent risk factors were anti-CD20 therapies and neurological disability, emerging as vital drivers of COVID-19 severity regardless of wave, period, or vaccination status.

Enhancing detection of SARS-CoV-2 re-infections using longitudinal sero-monitoring: demonstration of a methodology in a cohort of people experiencing homelessness in Toronto, Canada.

BACKGROUND: Accurate estimation of SARS-CoV-2 re-infection is crucial to understanding the connection between infection burden and adverse outcomes. However, relying solely on PCR testing results in underreporting. We present a novel approach that includes longitudinal serologic data, and compared it against testing alone among people experiencing homelessness. METHODS: We recruited 736 individuals experiencing homelessness in Toronto, Canada, between June and September 2021. Participants completed surveys and provided saliva and blood serology samples every three months over 12 months of follow-up. Re-infections were defined as: positive PCR or rapid antigen test (RAT) results > 90 days after initial infection; new serologic evidence of infection among individuals with previous infection who sero-reverted; or increases in anti-nucleocapsid in seropositive individuals whose levels had begun to decrease. RESULTS: Among 381 participants at risk, we detected 37 re-infections through PCR/RAT and 98 re-infections through longitudinal serology. The comprehensive method identified 37.4 re-infection events per 100 person-years, more than four-fold more than the rate detected through PCR/RAT alone (9.0 events/100 person-years). Almost all test-confirmed re-infections (85%) were also detectable by longitudinal serology. CONCLUSIONS: Longitudinal serology significantly enhances the detection of SARS-CoV-2 re-infections. Our findings underscore the importance and value of combining data sources for effective research and public health surveillance.

Improving diagnostic performance of coronavirus disease 2019 rapid antigen testing through computer-based feedback training using open-source experimental psychology software.

INTRODUCTION: Rapid antigen testing (RAT) results are visually read as whether colored line is present or absent. The subjective interpretation potentially misses detecting weak lines due to lower analyte concentration in samples tested, requiring training. Although routine test experience has improved the result readout skills, it consumes time and resources. Therefore, we created a computer-based feedback training method using open-source experimental psychology software, wherein participants accumulate RAT result readout experience by repeatedly responding positive/negative to randomly presented pictures showing RAT results; then, they receive feedback on their answers as correct or incorrect and are asked to stare at the pictures again with the knowledge of correct answer. This study aimed to examine the training effects in improving the skills, using coronavirus disease 2019 (COVID-19) RAT. METHODS: Twenty-two medical technologists were randomly divided into two groups: the feedback-training and test-experience groups. Using several pictures showing positive and negative results of COVID-19 RAT, after examination of their initial result readout skills, feedback-training group received the feedback training, whereas test-experience group performed an equal number of tests without feedback to accumulate test experience, and their skills were examined again. The ratio of "positive" answers to the pictures showing positive results (i.e., hit rate) was statistically analyzed. RESULTS: The feedback-training group showed a significantly higher hit rate after their training, whereas the test-experience group did not. The feedback training effects were manifested in weak line detection. CONCLUSIONS: This computer-based feedback training method can be an effective tool for improving RAT result readout skills.

Racial/ethnic differences in the associations between trust in the U.S. healthcare system and willingness to test for and vaccinate against COVID-19.

BACKGROUND: Trust in the healthcare system may impact adherence to recommended healthcare practices, including willingness to test for and vaccinate against COVID-19. This study examined racial/ethnic differences in the associations between trust in the U.S. healthcare system and willingness to test for and vaccinate against COVID-19 during the first year of the pandemic. METHODS: This cross-sectional study used data from the REACH-US study, a nationally representative online survey conducted among a diverse sample of U.S. adults from January 26, 2021-March 3, 2021 (N = 5,121). Multivariable logistic regression estimated the associations between trust in the U.S. healthcare system (measured as "Always", "Most of the time", "Sometimes/Almost Never", and "Never") and willingness to test for COVID-19, and willingness to receive the COVID-19 vaccine. Racial/ethnic differences in these associations were examined using interaction terms and multigroup analyses. RESULTS: Always trusting the U.S. healthcare system was highest among Hispanic/Latino Spanish Language Preference (24.9%) and Asian (16.7%) adults and lowest among Multiracial (8.7%) and Black/African American (10.7%) adults. Always trusting the U.S. healthcare system, compared to never, was associated with greater willingness to test for COVID-19 (AOR: 3.20, 95% CI: 2.38-4.30) and greater willingness to receive the COVID-19 vaccine (AOR: 2.68, 95% CI: 1.97-3.65). CONCLUSIONS: Trust in the U.S. healthcare system was associated with greater willingness to test for COVID-19 and receive the COVID-19 vaccine, however, trust in the U.S. healthcare system was lower among most marginalized racial/ethnic groups. Efforts to establish a more equitable healthcare system that increases trust may encourage COVID-19 preventive behaviors.

Health Behavior and Attitudes During the COVID-19 Pandemic Among Vulnerable and Underserved Latinx in the Southwest USA.

The COVID-19 pandemic highlighted deep-rooted health disparities, particularly among Latinx immigrants living on the Mexico-US border. This article investigates differences between populations and adherence to COVID-19 preventive measures. This study investigated whether there are differences between Latinx recent immigrants, non-Latinx Whites, and English-speaking Latinx in their attitudes and adherence to COVID-19 preventive measures. Data came from 302 participants who received a free COVID-19 test at one of the project sites between March and July 2021. Participants lived in communities with poorer access to COVID-19 testing. Choosing to complete the baseline survey in Spanish was a proxy for being a recent immigrant. Survey measures included the PhenX Toolkit, COVID-19 mitigating behaviors, attitudes toward COVID-19 risk behaviors and mask wearing, and economic challenges during the COVID-19 pandemic. With multiple imputation, ordinary least squares (OLS) regression was used to analyze between-group differences in mitigating attitudes and behaviors toward COVID-19 risk. Adjusted OLS regression analyses showed that Latinx surveyed in Spanish perceived COVID-19 risk behaviors as more unsafe (b = 0.38, p = .001) and had stronger positive attitudes toward mask wearing (b = 0.58, p = .016), as compared to non-Latinx Whites. No significant differences emerged between Latinx surveyed in English and non-Latinx Whites (p > .05). Despite facing major structural, economic, and systemic disadvantages, recent Latinx immigrants showed more positive attitudes toward public health COVID-19 mitigating measures than other groups. The findings have implications for future prevention research about community resilience, practice, and policy.

Rapidly developing communications materials during public health emergencies: the Âu CÆ¡ campaign in the USA.

During public health emergencies, health communication materials to contain the outbreak are needed promptly, which prevents the use of standard approaches for getting feedback from the intended audience. We propose a strategy for rapidly obtaining community feedback on new health communication materials during the public health emergencies. We illustrate this with COVID-19 testing campaign in a Vietnamese-American enclave in the USA. The project included community-based COVID-19 testing and communication activities to increase the awareness of the testing centers and encourage frequent testing. Our strategy involves two main components: (i) use of a research team with an existing trust relationship with the community and that includes researchers from that community and (ii) co-design of communication materials using community-based gatekeepers and a cultural broker. We developed brochures and posters to increase the awareness of the COVID-19 testing services. The cultural broker and community-based partners identified salient message concepts and worked with the researchers to define the objectives and content of the materials, which were then reviewed by the entire team. In lieu of standard pretesting, we relied on feedback on mockups of the materials and subsequent revisions from the community-based gatekeepers and cultural broker. Our strategy strikes a balance between the need to urgently disseminate new materials and the need for community input. One key takeaway is that effective planning for public health emergencies must start long before the crisis occurs.

Delayed Recognition of Coronavirus Disease 2019 (COVID-19) in New York City: A Descriptive Analysis of COVID-19 Illness Prior to 29 February 2020.

BACKGROUND: On 30 January 2020, COVID-19 was declared a Public Health Emergency of International Concern (PHEIC) by the World Health Organization. Almost a month later, on 29 February 2020, the first case in New York City (NYC) was diagnosed. METHODS: Three hundred sixty persons with COVID-19-like illness were reported to the NYC Department of Health and Mental Hygiene (DOHMH) before 29 February, but 37 of these tested negative and 237 were never tested for severe acute respiratory syndrome coronavirus 2. Records of 86 persons with confirmed COVID-19 and reported symptom onset prior to 29 February 2020 were reviewed by 4 physician-epidemiologists. Case-patients were classified as possible delayed recognition (PDR) of COVID-19 when upon medical review the reported onset date was believed to reflect the initial symptoms of COVID-19, or insufficient evidence to classify, when the onset could not be determined with confidence. Clinical and epidemiological factors collected by DOHMH and supplemented with emergency department records were analyzed. RESULTS: Thirty-nine PDR COVID-19 cases were identified. The majority had severe disease with 69% presenting to an emergency department within 2 weeks of symptom onset. The first PDR COVID-19 case had symptom onset on 28 January 2020. Only 7 of the 39 cases (18%) had traveled internationally within 14 days of onset (none to China). CONCLUSIONS: COVID-19 was in NYC before being classified as a PHEIC, and eluded surveillance for another month. The delay in recognition limited mitigation efforts; by the time city- and statewide mandates were enacted, 16 and 22 days later, there was already widespread community transmission.

COVID-19 Epidemiology during Delta Variant Dominance Period in 45 High-Income Countries, 2020-2021.

The SARS-CoV-2 Delta variant, first identified in October 2020, quickly became the dominant variant worldwide. We used publicly available data to explore the relationship between illness and death (peak case rates, death rates, case-fatality rates) and selected predictors (percentage vaccinated, percentage of the population >65 years, population density, testing volume, index of mitigation policies) in 45 high-income countries during the Delta wave using rank-order correlation and ordinal regression. During the Delta-dominant period, most countries reported higher peak case rates (57%) and lower peak case-fatality rates (98%). Higher vaccination coverage was protective against peak case rates (odds ratio 0.95, 95% CI 0.91-0.99) and against peak death rates (odds ratio 0.96, 95% CI 0.91-0.99). Vaccination coverage was vital to preventing infection and death from COVID-19 during the Delta wave. As new variants emerge, public health authorities should encourage the uptake of COVID-19 vaccination and boosters.

Preliminary Efficacy of a Theory-Informed Intervention to Increase COVID-19 Testing Uptake Among People Who Inject Drugs in San Diego County: Findings From a Pilot Randomized Controlled Trial.

BACKGROUND: People who inject drugs (PWID) have low rates of COVID-19 testing yet are vulnerable to severe disease. In partnership with a mobile syringe service program (SSP) in San Diego County, CA, we developed the evidence-, community-, and Social Cognitive Theory-informed "LinkUP" intervention (tailored education, motivational interviewing, problem-solving, and planning) to increase COVID-19 testing uptake among PWID. PURPOSE: To assess preliminary efficacy of LinkUP in increasing PWID COVID-19 testing in a pilot randomized controlled trial (RCT). METHODS: We referred participants (PWID, ≥18 years old, San Diego County residents who had not recently undergone voluntary COVID-19 testing) to mobile SSP sites that had been randomized (by week) to offer the active LinkUP intervention or didactic attention-control conditions delivered by trained peer counselors. Following either condition, counselors offered on-site rapid COVID-19 antigen testing. Analyses estimated preliminary intervention efficacy and explored potential moderation. RESULTS: Among 150 participants, median age was 40.5 years, 33.3% identified as Hispanic/Latinx, 64.7% were male, 73.3% were experiencing homelessness, and 44.7% had prior mandatory COVID-19 testing. The LinkUP intervention was significantly associated with higher COVID-19 testing uptake (p < .0001). Homelessness moderated intervention effects; LinkUP increased COVID-19 testing uptake more among participants experiencing homelessness (adjusted risk ratio [aRR]: 1.80; 95% CI: 1.56-2.09; p < .0001) than those not experiencing homelessness (aRR: 1.20; 95% CI: 1.01-1.43; p = .04). CONCLUSIONS: Findings from this pilot RCT support the preliminary efficacy of the "LinkUP" intervention to increase COVID-19 testing among PWID and underscore the importance of academic-community partnerships and prevention service delivery through SSPs and other community-based organizations serving vulnerable populations.

People who inject drugs (PWID) are vulnerable to severe COVID-19 disease yet have low rates of COVID-19 testing. We partnered with a syringe service program (SSP) in San Diego County, CA, to develop "LinkUP," an evidence- and community-informed intervention. Specifically, LinkUP used tailored education, motivational interviewing, and problem-solving and planning strategies to increase COVID-19 testing uptake among PWID. This study was a pilot randomized controlled trial (RCT) designed to assess the preliminary efficacy of LinkUP in increasing PWID COVID-19 testing. We referred participants (PWID, ≥18 years old, San Diego residents without recent voluntary COVID-19 testing) to mobile SSP sites that had been randomized (by week). Trained peer counselors then offered LinkUP or an educational control condition lasting the same length (~30 minutes). After either condition, counselors offered on-site rapid COVID-19 antigen testing. Among 150 participants, our analyses found that the LinkUP intervention was associated with higher COVID-19 testing uptake, especially for participants experiencing homelessness. In summary, our findings from this pilot RCT support the preliminary efficacy of the "LinkUP" intervention in increasing COVID-19 testing among PWID. This study also underscores the importance of academic-community partnerships and prevention service delivery through SSPs and other community-based organizations serving vulnerable populations.

Estimating the number of probable new SARS-CoV-2 infections among tested subjects from the number of confirmed cases.

OBJECTIVES: In most African countries, confirmed COVID-19 case counts underestimate the number of new SARS-CoV-2 infection cases. We propose a multiplying factor to approximate the number of biologically probable new infections from the number of confirmed cases. METHODS: Each of the first thousand suspect (or alert) cases recorded in South Kivu (DRC) between 29 March and 29 November 2020 underwent a RT-PCR test and an IgM and IgG serology. A latent class model and a Bayesian inference method were used to estimate (i) the incidence proportion of SARS-CoV-2 infection using RT-PCR and IgM test results, (ii) the prevalence using RT-PCR, IgM and IgG test results; and, (iii) the multiplying factor (ratio of the incidence proportion on the proportion of confirmed -RT-PCR+- cases). RESULTS: Among 933 alert cases with complete data, 218 (23%) were RT-PCR+; 434 (47%) IgM+; 464 (~ 50%) RT-PCR+, IgM+, or both; and 647 (69%) either IgG + or IgM+. The incidence proportion of SARS-CoV-2 infection was estimated at 58% (95% credibility interval: 51.8-64), its prevalence at 72.83% (65.68-77.89), and the multiplying factor at 2.42 (1.95-3.01). CONCLUSIONS: In monitoring the pandemic dynamics, the number of biologically probable cases is also useful. The multiplying factor helps approximating it.

COVID-19 Testing Among People with HIV: A Population Level Analysis Based on Statewide Data in South Carolina.

People with HIV (PWH) are at an elevated risk of developing severe COVID-19 outcomes because of compromised immunity and more comorbidities. However, existing literature suggests a lower rate of COVID-testing among PWH. This study aimed to explore the temporal trend of county-level COVID-19 testing rate and multi-level predictors of COVID-19 ever-testing among PWH in South Carolina (SC). Leveraging linked statewide HIV and COVID-19 datasets, we defined the study population as all adult (18 + years) PWH who were alive on March 2020 and living in SC. PWH with a COVID-19 testing record between March 2020 and October 2021 were defined as COVID-19 ever-testers. Logistic regression and generalized mixed models were used to investigate the association of PWH's demographic profile, HIV clinical characteristics (e.g., CD4 count, viral load), comorbidities, and social factors with COVID-19 testing among PWH. Among 15,660 adult PWH, 8,005 (51.12%) had ever tested for COVID-19 during the study period (March 2020-October 2021). PWH with older age, being male, and Hispanics were less likely to take COVID-19 testing, while men who have sex with men or injection drug users were more likely to take COVID-19 testing. PWH with higher recent viral load (10,000-100,000 copies/ml vs. <200 copies/ml: adjusted odds ratio [AOR]: 0.64, 95%CI: 0.55-0.75) and lower CD4 counts (> 350 cells/mm3 vs. <200 cells/mm3: AOR: 1.25, 95%CI: 1.09-1.45) had lower odds for COVID-19 testing. Additionally, PWH with lower comorbidity burden and those living in rural areas were less likely to be tested for COVID-19. Differences in COVID-19 test-seeking behaviors were observed among PWH in the current study, which could help provide empirical evidence to inform the prioritization of further disease monitoring and targeted intervention. More efforts on building effective surveillance and screening systems are needed to allow early case detection and curbing disease transmission among older, male, Hispanic, and immune-suppressed PWH, especially in rural areas.

COVID-19 Testing in a Weekly Cohort Study of Gay and Bisexual Men: The Impact of Health-Seeking Behaviors and Social Connection.

Gay, bisexual, and other men who have sex with men (GBM) have developed community norms for regular HIV/STI testing. We investigated factors associated with self-reported COVID-19 testing in response to reported COVID-19 cases and public health restrictions. Participants responded to weekly cohort surveys between 10th May 2021 and 27th September 2021. We used the Andersen-Gill extensions to the Cox proportional hazards model for multivariable survival data to predict factors influencing COVID-19 testing. Mean age of the 942 study participants was 45.6 years (SD: 13.9). In multivariable analysis, GBM were more likely to report testing during periods of high COVID-19 caseload in their state of residence; if they were younger; university educated; close contact of someone with COVID-19; or reported coping with COVID-19 poorly. COVID-19 testing was higher among men who: were more socially engaged with other GBM; had a higher proportion of friends willing to vaccinate against COVID-19; and were willing to contact sexual partners for contact tracing. Social connection with other gay men was associated with COVID-19 testing, similar to what has been observed throughout the HIV epidemic, making community networks a potential focus for the promotion of COVID-19 safe practices.

Patient characteristics and testing over COVID-19 waves 1 and 2 from the first German COVID-19 testing unit in Munich, Germany.

BACKGROUND: In Munich, the first German case of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was detected on 27 January 2020 at the Division of Infectious Diseases and Tropical Medicine of the University Hospital LMU Munich (DIDTM), and consecutively the Covid Testing Unit was established. Germany advocated several public health measures to control the outbreak. This study investigates the effects of measures on health service utilization in the public, which in turn can alter case numbers and test positivity rates. METHOD: Our retrospective observational study was conducted to determine the effects of public health measures on the utilization of a testing facility and positivity rates from the first operational COVID-19 testing facility in Munich for waves 1 and 2 over a period of 14 months. This was accomplished by comparing trends in client characteristics including age, gender, symptoms, and socio-demographic aspects over time to non-pharmaceutical measures in Germany. To depict trend changes in testing numbers over time, we developed a negative binomial model with multiple breakpoints. RESULTS: In total 9861 tests were conducted on 6989 clients. The clients were mostly young (median age: 34), female (60.58%), and asymptomatic (67.89%). Among those who tested positive for SARS-CoV-2, 67.72% were symptomatic while the percentage was 29.06% among those who tested negative. There are other risk factors, but a SARS-CoV-2-positive colleague at work is the most prominent factor. Trend changes in the clients' testing numbers could be attributed to the implementation of various public health measures, testing strategies, and attitudes of individuals toward the pandemic. However, test positivity rates did not change substantially during the second wave of the pandemic. CONCLUSION: We could show that implementation or changes in public health measures have a strong effect on the utilization of testing facilities by the general public, which independently of the true epidemiological background situation can result in changing test numbers.

Determining optimal COVID-19 testing center locations and capacities.

We study the problem of determining the locations and capacities of COVID-19 specimen collection centers to efficiently improve accessibility to polymerase chain reaction testing during surges in testing demand. We develop a two-echelon multi-period location and capacity allocation model that determines optimal number and locations of pop-up testing centers, capacities of the existing centers as well as assignments of demand regions to these centers, and centers to labs. The objective is to minimize the total number of delayed appointments and specimens subject to budget, capacity, and turnaround time constraints, which will in turn improve the accessibility to testing. We apply our model to a case study for locating COVID-19 testing centers in the Region of Waterloo, Canada using data from the Ontario Ministry of Health, public health databases, and medical literature. We also test the performance of the model under uncertain demand and analyze its outputs under various scenarios. Our analyses provide practical insights to the public health decision-makers on the timing of capacity expansions and the locations for the new pop-up centers. According to our results, the optimal strategy is to dynamically expand the existing specimen collection center capacities and prevent bottlenecks by locating pop-up facilities. The optimal locations of pop-ups are among the densely populated areas that are in proximity to the lab and a subset of those locations are selected with the changes in demand. A comparison with a static approach promises up to 39% cost savings under high demand using the developed multi-period model.

Understanding social risk factors of county-level disparities in COVID-19 tests per confirmed case in South Carolina using statewide electronic health records data.

BACKGROUND: COVID-19 testing is essential for pandemic control, and insufficient testing in areas with high disease burdens could magnify the risk of poor health outcomes. However, few area-based studies on COVID-19 testing disparities have considered the disease burden (e.g., confirmed cases). The current study aims to investigate socioeconomic drivers of geospatial disparities in COVID-19 testing relative to disease burden across 46 counties in South Carolina (SC) in the early (from April 1, 2020, to June 30, 2020) and later (from July 1, 2020, to September 30, 2021) phases of the pandemic. METHODS: Using SC statewide COVID-19 testing data, the COVID-19 testing coverage was measured by monthly COVID-19 tests per confirmed case (hereafter CTPC) in each county. We used modified Lorenz curves to describe the unequal geographic distribution of CTPC and generalized linear mixed-effects regression models to assess the association of county-level social risk factors with CTPC in two phases of the pandemic in SC. RESULTS: As of September 30, 2021, a total of 641,201 out of 2,941,227 tests were positive in SC. The Lorenz curve showed that county-level disparities in CTPC were less apparent in the later phase of the pandemic. Counties with a larger percentage of Black had lower CTPC during the early phase (ß = -0.94, 95%CI: -1.80, -0.08), while such associations reversed in the later phase (ß = 0.28, 95%CI: 0.01, 0.55). The association of some other social risk factors diminished as the pandemic evolved, such as food insecurity (ß: -1.19 and -0.42; p-value is < 0.05 for both). CONCLUSIONS: County-level disparities in CTPC and their predictors are dynamic across the pandemic. These results highlight the systematic inequalities in COVID-19 testing resources and accessibility, especially in the early stage of the pandemic. Counties with greater social vulnerability and those with fewer health care resources should be paid extra attention in the early and later phases, respectively. The current study provided empirical evidence for public health agencies to conduct more targeted community-based testing campaigns to enhance access to testing in future public health crises.

Diagnostic accuracy of a set of clinical and radiological criteria for screening of COVID-19 using RT-PCR as the reference standard.

BACKGROUND: The gold-standard method for establishing a microbiological diagnosis of COVID-19 is reverse-transcriptase polymerase chain reaction (RT-PCR). This study aimed to evaluate the accuracy, sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) of a set of clinical-radiological criteria for COVID-19 screening in patients with severe acute respiratory failure (SARF) admitted to intensive care units (ICUs), using reverse-transcriptase polymerase chain reaction (RT-PCR) as the reference standard. METHODS: Diagnostic accuracy study including a historical cohort of 1009 patients consecutively admitted to ICUs across six hospitals in Curitiba (Brazil) from March to September, 2020. The sample was stratified into groups by the strength of suspicion for COVID-19 (strong versus weak) using parameters based on three clinical and radiological (chest computed tomography) criteria. The diagnosis of COVID-19 was confirmed by RT-PCR (referent). RESULTS: With respect to RT-PCR, the proposed criteria had 98.5% (95% confidence interval [95% CI] 97.5-99.5%) sensitivity, 70% (95% CI 65.8-74.2%) specificity, 85.5% (95% CI 83.4-87.7%) accuracy, PPV of 79.7% (95% CI 76.6-82.7%) and NPV of 97.6% (95% CI 95.9-99.2%). Similar performance was observed when evaluated in the subgroups of patients admitted with mild/moderate respiratory disfunction, and severe respiratory disfunction. CONCLUSION: The proposed set of clinical-radiological criteria were accurate in identifying patients with strong versus weak suspicion for COVID-19 and had high sensitivity and considerable specificity with respect to RT-PCR. These criteria may be useful for screening COVID-19 in patients presenting with SARF.

Disparities in COVID-19 testing and outcomes among Asian American and Pacific Islanders: an observational study in a large health care system.

BACKGROUND: The COVID-19 pandemic has disproportionately impacted racial and ethnic minorities in the United States, including Asian Americans, Native Hawaiians and Pacific Islanders (Asian Americans and NH/PIs). However, few studies have highlighted nor disaggregated these disparities by Asian Americans and NH/PIs ethnic subgroups. METHODS: This retrospective, cross-sectional observational study aimed to assess variation of Asian Americans and NH/PIs COVID-19 testing and outcomes compared to non-Hispanic Whites (NHW). The study utilized data from the electronic health records (EHR) and the COVID-19 Universal Registry for Vital Evaluations (CURVE) from all patients tested for SARS-CoV-2 (n = 556,690) at a large, health system in Northern and Central California between February 20, 2020 and March 31, 2021. Chi-square tests were used for testing differences in the severity of COVID-19 (hospitalization, ICU admission, death) and patient demographic and clinical characteristics across the Asian Americans and NH/PIs subgroups and NHW. Unadjusted and adjusted Odds Ratios (ORs) were estimated for measuring effect of race ethnicity on severity of COVID-19 using multivariable logistic regression. RESULTS: Of the entire tested population, 70,564/556,690 (12.7%) tested positive for SARS-CoV-2. SARS-CoV-2 positivity of Asian subgroups varied from 4% in the Chinese and Korean populations, to 11.2%, 13.5%, and 12.5% for Asian Indian, Filipino, and "other Asian" populations respectively. Pacific Islanders had the greatest subgroup test positivity at 20.1%. Among Asian Americans and NH/PIs patients with COVID-19 disease, Vietnamese (OR = 2.06, 95% CI = 1.30-3.25), "Other Asian" (OR = 2.13, 95% CI = 1.79-2.54), Filipino (OR = 1.78, 95% CI = 1.34-2.23), Japanese (OR = 1.78, 95% CI = 1.10-2.88), and Chinese (OR = 1.73, 95% CI = 1.34-2.23) subgroups had almost double the odds of hospitalization compared to NHW. Pacific Islander (OR = 1.58, 95% CI = 1.19-2.10) and mixed race subgroups (OR = 1.55, 95% CI = 1.10-2.20) had more than one and a half times odds of hospitalization compared to NHW. Adjusted odds of ICU admission or death among hospitalized patients by different Asian subgroups varied but were not statistically significant. CONCLUSIONS: Variation of COVID-19 testing and hospitalization by Asian subgroups was striking in our study. A focus on the Asian Americans and NH/PIs population with disaggregation of subgroups is crucial to understand nuances of health access, utilization, and outcomes among subgroups to create health equity for these underrepresented populations.