Orthogonal SARS-CoV-2 Serological Assays Enable Surveillance of Low-Prevalence Communities and Reveal Durable Humoral Immunity.

We conducted a serological study to define correlates of immunity against SARS-CoV-2. Compared to those with mild coronavirus disease 2019 (COVID-19) cases, individuals with severe disease exhibited elevated virus-neutralizing titers and antibodies against the nucleocapsid (N) and the receptor binding domain (RBD) of the spike protein. Age and sex played lesser roles. All cases, including asymptomatic individuals, seroconverted by 2 weeks after PCR confirmation. Spike RBD and S2 and neutralizing antibodies remained detectable through 5-7 months after onset, whereas α-N titers diminished. Testing 5,882 members of the local community revealed only 1 sample with seroreactivity to both RBD and S2 that lacked neutralizing antibodies. This fidelity could not be achieved with either RBD or S2 alone. Thus, inclusion of multiple independent assays improved the accuracy of antibody tests in low-seroprevalence communities and revealed differences in antibody kinetics depending on the antigen. We conclude that neutralizing antibodies are stably produced for at least 5-7 months after SARS-CoV-2 infection.

Post Pulmonary Embolism Phenotypes Described by Invasive Cardiopulmonary Exercise Testing.

BACKGROUND: Post pulmonary embolism (PE) dyspnea is common. Existing non-invasive studies have demonstrated that post PE dyspnea is associated with elevations in right ventricular afterload, dead space ventilation, and deconditioning. We aimed to use invasive cardiopulmonary exercise testing (iCPET) parameters in patients with post PE dyspnea to identify unique physiologic phenotypes. RESEARCH QUESTION: Are there distinct post pulmonary embolism dyspnea physiologic phenotypes described with iCPET? STUDY DESIGN AND METHODS: Patients were enrolled at the time of acute PE and through our pulmonary hypertension and dyspnea clinic. ICPET was performed if there was high suspicion for pulmonary hypertension or if there was unexplained dyspnea. A hierarchical cluster analysis was performed to identify dyspnea phenotypes. ICPET parameters assessing pulmonary hemodynamics, ventilation, and peripheral oxygen utilization were then compared within and across each cluster and with iCPET controls against peak oxygen consumption (Peak VO2). RESULTS: 173 patients were enrolled. Sixty-seven patients underwent iCPET. All patients had reductions in Peak VO2 and peak cardiac index relative to controls. Three clusters were identified. Cluster one was defined by having elevated RV afterload and impaired ventilatory efficiency. Cluster two had elevated RV afterload with reductions in respiratory mechanics. Cluster three had mild derangement in RV afterload with mild reductions in peak cardiac output. INTERPRETATION: iCPET reveals significant heterogeneity in post PE dyspnea. Three phenotypes are characterized by differences in RV afterload, ventilatory efficiency, respiratory mechanics, and peripheral oxygen utilization.

SARS-CoV-2 Rapid Antigen Testing of Symptomatic and Asymptomatic Individuals on the University of Arizona Campus.

SARS-CoV-2, the cause of COVID19, has caused a pandemic that has infected more than 80 M and killed more than 1.6 M persons worldwide. In the US as of December 2020, it has infected more than 32 M people while causing more than 570,000 deaths. As the pandemic persists, there has been a public demand to reopen schools and university campuses. To consider these demands, it is necessary to rapidly identify those individuals infected with the virus and isolate them so that disease transmission can be stopped. In the present study, we examined the sensitivity of the Quidel Rapid Antigen test for use in screening both symptomatic and asymptomatic individuals at the University of Arizona from June to August 2020. A total of 885 symptomatic and 1551 asymptomatic subjects were assessed by antigen testing and real-time PCR testing. The sensitivity of the test for both symptomatic and asymptomatic persons was between 82 and 90%, with some caveats.