Evidence-driven spatiotemporal COVID-19 hospitalization prediction with Ising dynamics.

In this work, we aim to accurately predict the number of hospitalizations during the COVID-19 pandemic by developing a spatiotemporal prediction model. We propose HOIST, an Ising dynamics-based deep learning model for spatiotemporal COVID-19 hospitalization prediction. By drawing the analogy between locations and lattice sites in statistical mechanics, we use the Ising dynamics to guide the model to extract and utilize spatial relationships across locations and model the complex influence of granular information from real-world clinical evidence. By leveraging rich linked databases, including insurance claims, census information, and hospital resource usage data across the U.S., we evaluate the HOIST model on the large-scale spatiotemporal COVID-19 hospitalization prediction task for 2299 counties in the U.S. In the 4-week hospitalization prediction task, HOIST achieves 368.7 mean absolute error, 0.6 [Formula: see text] and 0.89 concordance correlation coefficient score on average. Our detailed number needed to treat (NNT) and cost analysis suggest that future COVID-19 vaccination efforts may be most impactful in rural areas. This model may serve as a resource for future county and state-level vaccination efforts.

Anatomy of an American football game: Player-to-player contact before, during and after an NFL game in context of the 2020 COVID-19 pandemic.

OBJECTIVES: To quantify levels of potential exposure to SARS-CoV-2 surrounding a typical professional American football game, with a focus on interactions on-field between teammates and opposing players before, during, and immediately after competition. METHODS: We examined across-Club consecutive interactions ≥2 minutes within 6 feet [1.8 meters] between athletes on opposing Clubs for all 2020 NFL regular season games (n = 256). Cumulative interaction was measured for a representative subset (n = 119; 46%) of games. Wearable proximity tracking devices (Kinexon) were used to measure distance and duration of interactions; these data were combined with game schedule and Club rosters for analyses. Frequency and per-game mean, median, interquartile range for consecutive interactions ≥2/≥5 minutes and cumulative interactions ≥5/≥15 were described overall and stratified by pre-game, in-game, and post-game. RESULTS: Of the 1964 distinct player-to-opponent contacts ≥2 minutes in NFL regular season games, the majority (n = 1,699; 87%) were fewer than 5 minutes in consecutive length. Among the mean 7.7 distinct contacts ≥2 minutes with opponents each game (median = 4; IQR = 2, 8), very few were ≥5 consecutive minutes at any point (mean = 1.0; median = 0; IQR = 0, 0). Most (n = 849; 43.2%) distinct contacts were pre-game, 546 (27.8%) were during competition, and 569 (29%) were post-game. In games where cumulative interactions were analyzed, there was an average of 17.1 player/opponent interactions with cumulative exposure ≥5 minutes (median = 12; IQR = 4, 30), almost all of which occurred during competition. CONCLUSION: There is limited and short contact between and among competing players in professional American football. In the setting of infectious disease such as the COVID-19 pandemic, a robust prevention program integrating masking, distancing, hygiene, and ventilation when off-field can be created to minimize on- and off-field exposures, which effectively reduces transmission risk in outdoors and/or well-ventilated stadium settings.

COVID-19 Vaccinations in Pregnancy: Comparative Evaluation of Acute Side Effects and Self-Reported Impact on Quality of Life between Pregnant and Nonpregnant Women in the United States.

OBJECTIVE: The objective of this study was to describe the acute side effects experienced by pregnant women who received a coronavirus disease 2019 (COVID-19) vaccine in the United States and to compare their experience to nonpregnant women of similar age. STUDY DESIGN: Adults who received a COVID-19 vaccine in the United States were invited via social media to enroll in an online, longitudinal, community-based registry ( www.helpstopCOVID19.com ). Participants self-reported pregnancy status, vaccination dates, manufacturer, acute side effects, impact on work and self-care, medical consultation, and hospitalization. This analysis was restricted to women aged 20 to 39 at the time of vaccination. Side effects reported by pregnant women were compared to those reported by nonpregnant women. RESULTS: This analysis included 946 pregnant women, with 572 (60%) receiving at least one dose of Pfizer, 321 (34%) Moderna, and 53 (6%) J&J, and 1,178 nonpregnant women. Demographic and medical history were similar across manufacturers for both cohorts.Overall, pregnant women reported similar side effects as nonpregnant women, with the most common being injection site reactions (83 vs. 87%), fatigue (72 vs.78%), and headache (45 vs. 59%). Pregnant women reported fewer side effects (median: 3 vs. 4, respectively). In both cohorts, very few reported seeking medical care (<5%) or being hospitalized (<0.3%) after vaccination. Fewer pregnant women reported working less after vaccination than nonpregnant women (32 vs. 40%) or trouble with self-care (32 vs. 46%), respectively. CONCLUSION: Pregnant women reported similar COVID-19 vaccine side effects as nonpregnant women, although fewer total side effects; pregnant women judged these side effects to have less impact on work and self-care. While these results do not address pregnancy outcomes or long-term effects, findings about acute side effects and impact offer reassurance for all three vaccines in terms of tolerability. KEY POINTS: · COVID vaccines were well tolerated by pregnant women.. · Pregnant women reported fewer total side effects.. · Pregnant women reported less impact on work and self-care..

Quantifying the impact of immune history and variant on SARS-CoV-2 viral kinetics and infection rebound: A retrospective cohort study.

Background: The combined impact of immunity and SARS-CoV-2 variants on viral kinetics during infections has been unclear. Methods: We characterized 1,280 infections from the National Basketball Association occupational health cohort identified between June 2020 and January 2022 using serial RT-qPCR testing. Logistic regression and semi-mechanistic viral RNA kinetics models were used to quantify the effect of age, variant, symptom status, infection history, vaccination status and antibody titer to the founder SARS-CoV-2 strain on the duration of potential infectiousness and overall viral kinetics. The frequency of viral rebounds was quantified under multiple cycle threshold (Ct) value-based definitions. Results: Among individuals detected partway through their infection, 51.0% (95% credible interval [CrI]: 48.3-53.6%) remained potentially infectious (Ct <30) 5 days post detection, with small differences across variants and vaccination status. Only seven viral rebounds (0.7%; N=999) were observed, with rebound defined as 3+days with Ct <30 following an initial clearance of 3+days with Ct ≥30. High antibody titers against the founder SARS-CoV-2 strain predicted lower peak viral loads and shorter durations of infection. Among Omicron BA.1 infections, boosted individuals had lower pre-booster antibody titers and longer clearance times than non-boosted individuals. Conclusions: SARS-CoV-2 viral kinetics are partly determined by immunity and variant but dominated by individual-level variation. Since booster vaccination protects against infection, longer clearance times for BA.1-infected, boosted individuals may reflect a less effective immune response, more common in older individuals, that increases infection risk and reduces viral RNA clearance rate. The shifting landscape of viral kinetics underscores the need for continued monitoring to optimize isolation policies and to contextualize the health impacts of therapeutics and vaccines. Funding: Supported in part by CDC contract #200-2016-91779, a sponsored research agreement to Yale University from the National Basketball Association contract #21-003529, and the National Basketball Players Association.

Evaluating real-world COVID-19 vaccine effectiveness using a test-negative case-control design.

Aim: It is important to assess if clinical trial efficacy translates into real-world effectiveness for COVID-19 vaccines. Materials & methods: We conducted a modified test-negative design (TND) to evaluate the real-world effectiveness of three COVID-19 vaccines. We defined cases in two ways: self-reported COVID-19-positive tests, and self-reported positive tests with ≥1 moderate/severe COVID-19 symptom. Results: Any vaccination was associated with a 95% reduction in subsequently reporting a positive COVID-19 test, and a 71% reduction in reporting a positive test and ≥1 moderate/severe symptom. Conclusion: We observed high effectiveness across all three marketed vaccines, both for self-reported positive COVID-19 tests and moderate/severe COVID-19 symptoms. This innovative TND approach can be implemented in future COVID-19 vaccine and treatment real-world effectiveness studies. Clinicaltrials.gov identifier: NCT04368065.

COVID-19 Vaccination Breakthrough Infections in a Real-World Setting: Using Community Reporters to Evaluate Vaccine Effectiveness.

Purpose: Coronavirus disease 2019 (COVID-19) has highlighted the need for new methods of pharmacovigilance. Here, we use adult community volunteers to obtain systematic information on vaccine effectiveness and the nature and severity of breakthrough infections. Methods: Between December 15, 2020 and September 16, 2021, 11,826 unpaid community-based volunteers reported the following information to an on-line registry: COVID-19 test results, vaccination (Pfizer, Moderna, or Johnson & Johnson) and COVID-19 symptoms. COVID-19 infections were described based on vaccination status at the time of infection: 1) fully vaccinated, 2) partially vaccinated (received first of two-dose vaccines or were <14 days post-final dose), or 3) unvaccinated. Results: Among 8554 participants who received any COVID-19 vaccine, COVID-19 infections were reported by 74 (1.0%) of those who were fully vaccinated and 198 (2.3%) of those who were partially vaccinated at the time of infection. Among the 74 participants who reported a breakthrough infection after full vaccination, the median time from vaccination to reported positive test result was 104.5 days (interquartile range: 77-135 days), with no difference among vaccine manufacturers. One quarter (25.7%) of breakthrough infections in the fully vaccinated cases were asymptomatic and most (>97%) fully vaccinated participants reported no symptoms or only mild symptoms compared to 89.3% of the unvaccinated cases. Only 1.4% of fully vaccinated participants reported experiencing at least 3 moderate-to-severe symptoms compared to 7.8% in the unvaccinated. Conclusion: Person-generated health data, also referred to as patient-reported outcomes, is a useful approach for quantifying breakthrough infections and their severity and for comparing vaccines. Trial Registration: Clinicaltrials.gov NCT04368065, EU PAS Register EUPAS36240.

Effectiveness and use of reverse transcriptase polymerase chain reaction point of care testing in a large-scale COVID-19 surveillance system.

BACKGROUND: Rapid COVID-19 testing platforms can identify infected individuals at the point of care (POC), allowing immediate isolation of infected individuals and reducing the risk of transmission. While lab-based nucleic acid amplification testing (NAAT) is often considered the gold standard to detect SARS-CoV-2 in the community, results typically take 2-7 days to return, rendering POC testing a critical diagnostic tool for infection control. The National Football League (NFL) and NFL Players Association deployed a new POC testing strategy using a newly available reverse transcriptase polymerase chain reaction (RT-PCR) rapid test during the 2020 season, and evaluated diagnostic effectiveness compared to other available devices using real-world population surveillance data. METHODS: RT-PCR POC test results were compared to NAAT results from same-day samples by calculation of positive and negative concordance. Sensitivity analyses were performed for three subgroups: (1) individuals symptomatic at time of positive test; (2) individuals tested during the pilot phase of rollout; and (3) individuals tested daily. RESULTS: Among 4989 same-day POC/NAAT pairs, 4957 (99.4%) were concordant, with 93.1% positive concordance and 99.6% negative concordance. Based on adjudicated case status, the false negative rate was 0.2% and false positive rate was 2.9%. In 43 instances, the immediate turnaround of results by POC allowed isolation of infected individuals 1 day sooner than lab-based testing. Positive/negative concordance in sensitivity analyses were relatively stable. CONCLUSION: RT-PCR POC testing provided timely results that were highly concordant with lab-based NAAT in population surveillance. Expanded use of effective RT-PCR POC can enable rapid isolation of infected individuals and reduce COVID-19 infection in the community.

Severe Acute Respiratory Syndrome Coronavirus 2 Reinfection: A Case Series From a 12-Month Longitudinal Occupational Cohort.

Findings are described in 7 patients with severe acute respiratory syndrome coronavirus 2 reinfection from the National Basketball Association 2020-2021 occupational testing cohort, including clinical details, antibody test results, genomic sequencing, and longitudinal reverse-transcription polymerase chain reaction results. Reinfections were infrequent and varied in clinical presentation, viral dynamics, and immune response.

Results from a Test-to-Release from Isolation Strategy Among Fully Vaccinated National Football League Players and Staff Members with COVID-19 - United States, December 14-19, 2021.

During December 2021, the United States experienced a surge in COVID-19 cases, coinciding with predominance of the SARS-CoV-2 B.1.1.529 (Omicron) variant (1). During this surge, the National Football League (NFL) and NFL Players Association (NFLPA) adjusted their protocols for test-to-release from COVID-19 isolation on December 16, 2021, based on analytic assessments of their 2021 test-to-release data. Fully vaccinated* persons with COVID-19 were permitted to return to work once they were asymptomatic or fever-free and experiencing improving symptoms for ≥24 hours, and after two negative or high cycle-threshold (Ct) results (Ct≥35) from either of two reverse transcription-polymerase chain reaction (RT-PCR) tests† (2). This report describes data from NFL's SARS-CoV-2 testing program (3) and time to first negative or Ct≥35 result based on serial COVID-19 patient testing during isolation. Among this occupational cohort of 173 fully vaccinated adults with confirmed COVID-19 during December 14-19, 2021, a period of Omicron variant predominance, 46% received negative test results or had a subsequent RT-PCR test result with a Ct≥35 by day 6 postdiagnosis (i.e., concluding 5 days of isolation) and 84% before day 10. The proportion of persons with positive test results decreased with time, with approximately one half receiving positive RT-PCR test results after postdiagnosis day 5. Although this test result does not necessarily mean these persons are infectious (RT-PCR tests might continue to return positive results long after an initial positive result) (4), these findings indicate that persons with COVID-19 should continue taking precautions, including correct and consistent mask use, for a full 10 days after symptom onset or initial positive test result if they are asymptomatic.

How frequent are acute reactions to COVID-19 vaccination and who is at risk?

INTRODUCTION: Our objective was to describe and compare self-reported side effects ofCOVID-19 vaccinesin theUSA. METHODS: Aweb-basedregistry enrolled volunteers who received a COVID-19 vaccine between March 19-July 15, 2021. We collected self-reported short-term side effects, medical consultation, hospitalization, and quality of life impact following completed vaccination regimens (Pfizer, Moderna, J&J). RESULTS: We recruited 6,966 volunteers who completed their full course of vaccination (median age 48 years, IQR 35.0-62.0; 83.6% female): Pfizer 3,486; Moderna 2,857; J&J 623. Few (3.1%) sought medical care for post-vaccination side effects. Hospitalization (n = 17; 0.3%) and severe allergic reactions (n = 39; 0.6%) also were rare. Those with autoimmune disease or lung disease were approximately twice as likely to seek medical care (adjusted odds ratio (aOR) 2.01, 95% CI:1.39; 2.92 and aOR 1.70, 95% CI: 1.12; .58 respectively). 92.4% of participantsreported ≥ 1side effect (median 3), with injection site reactions (78.9%), fatigue (70.3%), headache (49.0%) reported most frequently. More side effects were reported after the second dose of two-dose vaccines (medians: 1 vs. 2 for Pfizer and 1 vs. 3 for Moderna for first and second doses respectively) versus 3 for J&J's single-dose vaccine. For the employed, the median number of workdays missed was one. Diabetics and those vaccinated against influenza were substantially less likely to report 3 or more symptoms (aOR 0.68, 95% CI: 0.56;0.82] and aOR 0.82, 95% CI: 0.73;0.93, respectively). DISCUSSION: The total side effect burden was, not unexpectedly, greater with two-dose regimens but all three vaccines appear relatively safe. Very few subjects reported side effects serious enough to warrant medical care or reported post-vaccination hospitalization. While these findings do not address possible long-term effects, they do inform on their short-term safety and tolerability and will hopefully provide some reassurance and positively inform the benefit-risk and pharmacoeconomic assessment for all three vaccines. See Clinicaltrials.gov NCT04368065.

Population testing for COVID-19: an approach for infection prevention

BackgroundPopulation screening with highly sensitive diagnostic tools, such as nucleic acid amplification testing (NAAT), can enable early identification and isolation of cases and reduce transmission of SARS-CoV-2.ObjectiveTo describe the results of a rigorous, large-scale COVID-19 testing and monitoring program with confirmatory processes and adjudication of positive results.DesignDescriptive Epidemiology StudySetting32 U.S. National Football League (NFL) Clubs during the 2020 seasonParticipantsNFL players and staffMethodsThe NFL/NFL Players Association instituted a COVID-19 Testing and Surveillance Program for the 2020 Season, which included daily testing for players and staff, full medical follow-up and adjudication of cases. Clinical adjudication was based on subsequent daily testing, symptoms, and clinical history;persons remained in isolation during adjudication.ResultsBetween August 1 and November 14, 2020, a total of 632,370 RT-PCR tests were administered to 11,668 individuals;270 (2.4%) confirmed cases were observed. PPVs of the initial positive result ranged from 73–82% across RT-PCR platforms. Initial positive results were positive on re-processing 61–79% of the time. PPV increased when both results were positive to >95%;however, initial positives that were negative on confirmatory processing resulted in true cases a portion of the time, depending on machine and population prevalence. High Ct values (33 to 37) could indicate onset of infection. Infected individuals were identified and isolated early in infection, preventing spread.InterventionsDaily or frequent testing using three NAAT platforms, rapid point-of-care testing, and symptom monitoring.Main Outcome MeasurementsCOVID-19 infection.ConclusionRoutine RT-PCR testing allowed early detection of infection. Cycle threshold values provided a useful guidepost for understanding results. Confirmatory processing of initial positive values significantly improved PPV. Antigen POC testing was unable to reliably rule out COVID-19 early in infection. Adjudication processes were able to confirm or rule out SARS-CoV-2.

Optimizing SARS-CoV-2 Surveillance in the United States: Insights From the National Football League Occupational Health Program.

BACKGROUND: Evidence to understand effective strategies for surveillance and early detection of SARS-CoV-2 is limited. OBJECTIVE: To describe the results of a rigorous, large-scale COVID-19 testing and monitoring program. DESIGN: The U.S. National Football League (NFL) and the NFL Players Association (NFLPA) instituted a large-scale COVID-19 monitoring program involving daily testing using 2 reverse transcription polymerase chain reaction (RT-PCR) platforms (Roche cobas and Thermo Fisher QuantStudio), a transcription-mediated amplification platform (Hologic Panther), and an antigen point-of-care (aPOC) test (Quidel Sofia). SETTING: 32 NFL clubs in 24 states during the 2020 NFL season. PARTICIPANTS: NFL players and staff. MEASUREMENTS: SARS-CoV-2 test results were described in the context of medically adjudicated status. Cycle threshold (Ct) values are reported when available. RESULTS: A total of 632 370 tests administered across 11 668 persons identified 270 (2.4%) COVID-19 cases from 1 August to 14 November 2020. Positive predictive values ranged from 73.0% to 82.0% across the RT-PCR platforms. High Ct values (33 to 37) often indicated early infection. For the first positive result, the median Ct value was 32.77 (interquartile range, 30.02 to 34.72) and 22% of Ct values were above 35. Among adjudicated COVID-19 cases tested with aPOC, 42.3% had a negative result. Positive concordance between aPOC test result and adjudicated case status increased as viral load increased. LIMITATIONS: Platforms varied by laboratory, and test variability may reflect procedural differences. CONCLUSION: Routine RT-PCR testing allowed early detection of infection. Cycle threshold values provided a useful guidepost for understanding results, with high values often indicating early infection. Antigen POC testing was unable to reliably rule out COVID-19 early in infection. PRIMARY FUNDING SOURCE: The NFL and the NFLPA.

Observed Versus Expected COVID-19 Infections Among National Football League Players During the 2020 Season.

BACKGROUND: The National Football League (NFL) and National Football League Players Association implemented a set of strict protocols for the 2020 season with the intent to mitigate COVID-19 risk among players and staff. In that timeframe, the league's 32 teams completed 256 regular season games and several thousand meetings and practices. In parallel, community cases of COVID-19 were highly prevalent. We assess the risk of holding a 2020 NFL season by comparing community and player COVID-19 infections. METHODS: We used county-level COVID-19 test data from each team to establish baseline distributions of infection rates expected to occur in a population similar in age and sex to NFL players. We used a binomial distribution to simulate expected infections in each community cohort and compared these findings with observed COVID-19 infections in players. RESULTS: Over a 5-month period (1 August 2020 to 2 January 2021), positive NFL player infections (n = 256) were 55.7% lower than expected when compared with simulations from NFL community cohorts. For 30 of 32 teams (94%), observed counts fell at or below expectation, including 28 teams (88%) for which rates were lower. Two teams fell above baseline expectation. CONCLUSIONS: The NFL/NFLPA protocols that governed team facilities, travel, gameday, and activities outside of the workplace were associated with lower infection rates among NFL players compared with the surrounding community. The NFL's 2020-2021 season are consistent with the hypothesis that robust testing and behavioral protocols support a safe return to sport and work.

Viral dynamics of acute SARS-CoV-2 infection and applications to diagnostic and public health strategies.

SARS-CoV-2 infections are characterized by viral proliferation and clearance phases and can be followed by low-level persistent viral RNA shedding. The dynamics of viral RNA concentration, particularly in the early stages of infection, can inform clinical measures and interventions such as test-based screening. We used prospective longitudinal quantitative reverse transcription PCR testing to measure the viral RNA trajectories for 68 individuals during the resumption of the 2019-2020 National Basketball Association season. For 46 individuals with acute infections, we inferred the peak viral concentration and the duration of the viral proliferation and clearance phases. According to our mathematical model, we found that viral RNA concentrations peaked an average of 3.3 days (95% credible interval [CI] 2.5, 4.2) after first possible detectability at a cycle threshold value of 22.3 (95% CI 20.5, 23.9). The viral clearance phase lasted longer for symptomatic individuals (10.9 days [95% CI 7.9, 14.4]) than for asymptomatic individuals (7.8 days [95% CI 6.1, 9.7]). A second test within 2 days after an initial positive PCR test substantially improves certainty about a patient's infection stage. The effective sensitivity of a test intended to identify infectious individuals declines substantially with test turnaround time. These findings indicate that SARS-CoV-2 viral concentrations peak rapidly regardless of symptoms. Sequential tests can help reveal a patient's progress through infection stages. Frequent, rapid-turnaround testing is needed to effectively screen individuals before they become infectious.

SARS-CoV-2 Transmission Risk Among National Basketball Association Players, Staff, and Vendors Exposed to Individuals With Positive Test Results After COVID-19 Recovery During the 2020 Regular and Postseason.

Importance: Clinical data are lacking regarding the risk of viral transmission from individuals who have positive reverse-transcription-polymerase chain reaction (RT-PCR) SARS-CoV-2 test results after recovery from COVID-19. Objective: To describe case characteristics, including viral dynamics and transmission of infection, for individuals who have clinically recovered from SARS-CoV-2 infection but continued to have positive test results following discontinuation of isolation precautions. Design, Setting, and Participants: This retrospective cohort study used data collected from June 11, 2020, to October 19, 2020, as part of the National Basketball Association (NBA) closed campus occupational health program in Orlando, Florida, which required daily RT-PCR testing and ad hoc serological testing for SARS-CoV-2 IgG antibodies. Nearly 4000 NBA players, staff, and vendors participated in the NBA's regular and postseason occupational health program in Orlando. Persistent positive cases were those who recovered from a documented SARS-CoV-2 infection, satisfied US Centers for Disease Control and Prevention criteria for discontinuation of isolation precautions, and had at least 1 postinfection positive RT-PCR test(s) result. Exposures: Person-days of participation in indoor, unmasked activities that involved direct exposure between persistent positive cases and noninfected individuals. Main Outcomes and Measures: Transmission of SARS-CoV-2 following interaction with persistent positive individuals, as measured by the number of new COVID-19 cases in the Orlando campus program. Results: Among 3648 individuals who participated, 36 (1%) were persistent positive cases, most of whom were younger than 30 years (24 [67%]) and male (34 [94%]). Antibodies were detected in 33 individuals (91.7%); all remained asymptomatic following the index persistent positive RT-PCR result. Cycle threshold values for persistent positive RT-PCR test results were typically above the Roche cobas SARS-CoV-2 limit of detection. Cases were monitored for up to 100 days (mean [SD], 51 [23.9] days), during which there were at least 1480 person-days of direct exposure activities, with no transmission events or secondary infections of SARS-CoV-2 detected (0 new cases). Conclusions and Relevance: In this retrospective cohort study of the 2020 NBA closed campus occupational health program, recovered individuals who continued to test positive for SARS-CoV-2 following discontinuation of isolation were not infectious to others. These findings support time-based US Centers of Disease Control and Prevention recommendations for ending isolation.

Implementation and Evolution of Mitigation Measures, Testing, and Contact Tracing in the National Football League, August 9-November 21, 2020.

The National Football League (NFL) and the NFL Players Association (NFLPA) began the 2020 football season in July, implementing extensive mitigation and surveillance measures in facilities and during travel and gameplay. Mitigation protocols* were evaluated and modified based on data from routine reverse transcription-polymerase chain reaction (RT-PCR) tests for SARS-CoV-2, the virus that causes coronavirus 2019 (COVID-19); proximity tracking devices; and detailed interviews. Midseason, transmission was observed in persons who had cumulative interactions of <15 minutes' duration, leading to a revised definition of high-risk contacts that required consideration of mask use, setting and room ventilation in addition to proximity and duration of interaction. The NFL also developed an intensive protocol that imposed stricter infection prevention precautions when a case was identified at an NFL club. The intensive protocol effectively prevented the occurrence of high-risk interactions, with no high-risk contacts identified for 71% of traced cases at clubs under the intensive protocol. The incorporation of the nature and location of the interaction, including mask use, indoor versus outdoor setting, and ventilation, in addition to proximity and duration, likely improved identification of exposed persons at higher risk for SARS-CoV-2 infection. Quarantine of these persons, along with testing and intensive protocols, can reduce spread of infection.

Self-reported symptoms from exposure to Covid-19 provide support to clinical diagnosis, triage and prognosis: An exploratory analysis.

BACKGROUND: Symptomatic COVID-19 is prevalent in the community. We identify factors indicating COVID-19 positivity in non-hospitalized patients and prognosticators of moderate-to-severe disease. METHODS: Appeals conducted in April-June 2020 in social media, collaborating medical societies and patient advocacy groups recruited 20,476 participants ≥18 years who believed they had COVID-19 exposure. Volunteers consented on-line and reported height, weight, concomitant illnesses, medication and supplement use, residential, occupational or community COVID-19 exposure, symptoms and symptom severity on a 4-point scale. Of the 12,117 curated analytic population 2279 reported a COVID-19 viral test result: 865 positive (COVID+) and 1414 negative (COVID-). RESULTS: The triad of anosmia, ageusia and fever best distinguished COVID+ from COVID-participants (OR 6.07, 95% CI: 4.39 to 8.47). COVID + subjects with BMI≥30, concomitant respiratory disorders or an organ transplant had increased risk of moderate-to- severe dyspnoea. Race and anti-autoimmunity medication did not affect moderate-to-severe dyspnea risk. CONCLUSIONS: The triad of anosmia, ageusia and fever differentiates COVID-19. Elevated risks of severe symptoms outside the hospital were most evident among the obese and those with pulmonary comorbidity. Race and use of medication for autoimmune disease did not predict severe disease. These findings should facilitate rapid COVID-19 diagnosis and triage in settings without testing.