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 noninvasive studies have demonstrated that post-PE dyspnea is associated with elevations in right ventricular (RV) 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: Do distinct post-PE dyspnea physiologic phenotypes exist that are described with iCPET? STUDY DESIGN AND METHODS: Patients were enrolled at the time of acute PE and through our pulmonary hypertension (PH) and dyspnea clinic. iCPET was performed if high suspicion existed for PH or if unexplained dyspnea was present. A hierarchical cluster analysis was performed to identify dyspnea phenotypes. iCPET parameters assessing pulmonary hemodynamics, ventilation, and peripheral oxygen use then were compared within and across each cluster and with iCPET control participants against peak oxygen consumed per minute (VO2). RESULTS: One hundred seventy-three patients were enrolled. Sixty-seven patients underwent iCPET. All patients showed reductions in peak VO2 and peak cardiac index relative to control participants. Three clusters were identified. Cluster 1 was defined by having elevated RV afterload and impaired ventilatory efficiency. Cluster 2 was defined by elevated RV afterload with reductions in respiratory mechanics. Cluster 3 was defined by mild derangement in RV afterload with mild reductions in peak cardiac output. INTERPRETATION: iCPET revealed significant heterogeneity in post-PE dyspnea. Three phenotypes are characterized by differences in RV afterload: ventilatory efficiency, respiratory mechanics, and peripheral oxygen use.

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.