This article summarizes what is currently known about the 2019 novel coronavirus and offers interim guidance.

To determine prevalence of, seroprevalence of, and potential exposure to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) among a cohort of evacuees returning to the United States from Wuhan, China, in January 2020, we conducted a cross-sectional study of quarantined evacuees from 1 repatriation flight. Overall, 193 of 195 evacuees completed exposure surveys and submitted upper respiratory or serum specimens or both at arrival in the United States. Nearly all evacuees had taken preventive measures to limit potential exposure while in Wuhan, and none had detectable SARS-CoV-2 in upper respiratory tract specimens, suggesting the absence of asymptomatic respiratory shedding among this group at the time of testing. Evidence of antibodies to SARS-CoV-2 was detected in 1 evacuee, who reported experiencing no symptoms or high-risk exposures in the previous 2 months. These findings demonstrated that this group of evacuees posed a low risk of introducing SARS-CoV-2 to the United States.

Background: In the United States, the seasonality of respiratory syncytial virus (RSV) has traditionally been defined on the basis of weeks during which antigen-based tests detect RSV in >10% of specimens (hereafter, the "10% threshold"). Because molecular testing has become more widely used, we explored the extent of polymerase chain reaction (PCR)-based RSV testing and its impact on determining the seasonality of RSV. Methods: We assessed antigen- and PCR-based RSV reports submitted to the National Respiratory and Enteric Virus Surveillance System during July 2005-June 2015. To characterize RSV seasons by using PCR-based reports, we assessed the traditional 10% threshold; subsequently, we developed 3 methods based on either PCR-based detections or the percentage of positive test results. Results: The annual number of PCR-based reports increased 200-fold during 2005-2015, while the annual number of antigen-based reports declined. The weekly percentage of specimens positive for RSV by PCR was less than that for antigen-detection tests; accordingly, the 10% threshold excluded detections by PCR and so was imprecise for characterizing RSV seasons. Among our PCR-specific approaches, the most sensitive and consistent method captured 96%-98% of annual detections within a season, compared with 82%-94% captured using the traditional method. Conclusions: PCR-based reports are increasingly relevant for RSV surveillance and determining the seasonality of RSV. These PCR-specific methods provide a more comprehensive understanding of RSV trends, particularly in settings where testing and reporting are most active. Diagnostic practices will vary by locality and should be understood before choosing which method to apply.

Both molecular and serological assays have been used previously to determine the etiology of community-acquired pneumonia (CAP). However, the correlation of these methods and added diagnostic value of serology has not been fully evaluated. Using data from patients enrolled in the Centers for Disease Control and Prevention Etiology of Pneumonia in the Community (EPIC) study, we compared real-time RT-PCR and serology for diagnosis of respiratory syncytial virus (RSV), human metapneumovirus (HMPV), parainfluenza viruses 1-3 (PIV) and adenovirus (AdV) infections. Of 5126 patients enrolled, RT-PCR and serology test results were available for 2023, including 1087 children <18 years of age and 936 adults. For RSV, 287 (14.2%) patients were positive by RT-PCR and 234 (11.6%) were positive by serology; HMPV, 172 (8.5%) tested positive by RT-PCR and 147 (7.3%) by serology; PIVs, 94 (4.6%) tested positive by RT-PCR and 92 (4.6%) by serology; and AdV, 111 (5.5%) positive by RT-PCR and 62 (3.1%) by serology. RT-PCR provided the most positive detections overall, but serology increased diagnostic yield for RSV (by 11.8%), HMPV (by 25.0%), AdV (by 32.4%), and PIV (by 48.9%). Method concordance estimated by Cohen's kappa (kappa) coefficient ranged from good (RSV, 0.73 kappa) to fair (AdV, 0.27 kappa). Heterotypic seroresponses observed between PIV and persistent low-level AdV shedding may account for higher method discordance observed with each of these viruses. Serology can be a helpful adjunct to RT-PCR for research-based assessment of the etiologic contribution of non-influenza respiratory viruses to CAP.