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

OBJECTIVES: Nonpharmaceutical interventions against coronavirus disease 2019 likely have a role in decreasing viral acute respiratory illnesses (ARIs). We aimed to assess the frequency of respiratory syncytial virus (RSV) and influenza ARIs before and during the coronavirus disease 2019 pandemic. METHODS: This study was a prospective, multicenter, population-based ARI surveillance, including children seen in the emergency departments and inpatient settings in 7 US cities for ARI. Respiratory samples were collected and evaluated by molecular testing. Generalized linear mixed-effects models were used to evaluate the association between community mitigation and number of eligible and proportion of RSV and influenza cases. RESULTS: Overall, 45 759 children were eligible; 25 415 were enrolled and tested; 25% and 14% were RSV-positive and influenza-positive, respectively. In 2020, we noted a decrease in eligible and enrolled ARI subjects after community mitigation measures were introduced, with no RSV or influenza detection from April 5, 2020, to April 30, 2020. Compared with 2016-2019, there was an average of 10.6 fewer eligible ARI cases per week per site and 63.9% and 45.8% lower odds of patients testing positive for RSV and influenza, respectively, during the 2020 community mitigation period. In all sites except Seattle, the proportions of positive tests for RSV and influenza in the 2020 community mitigation period were lower than predicted. CONCLUSIONS: Between March and April 2020, rapid declines in ARI cases and the proportions of RSV and influenza in children were consistently noted across 7 US cities, which could be attributable to community mitigation measures against severe acute respiratory syndrome coronavirus 2.

Previous reports of COVID-19 among US children have been based on health jurisdiction reporting. We performed SARS-CoV-2 testing on children enrolled in active, prospective, multi-center surveillance during January-March, 2020. Among 3187 children, only 4 (0.1%) SARS-CoV-2-positive cases were identified March 20-31 despite evidence of rising community circulation.

Background: An outbreak of Middle East respiratory syndrome coronavirus (MERS-CoV) in Jordan in 2015 involved a variant virus that acquired distinctive deletions in the accessory open reading frames. We conducted a molecular and seroepidemiologic investigation to describe the deletion variant's transmission patterns and epidemiology. Methods: We reviewed epidemiologic and medical chart data and analyzed viral genome sequences from respiratory specimens of MERS-CoV cases. In early 2016, sera and standardized interviews were obtained from MERS-CoV cases and their contacts. Sera were evaluated by nucleocapsid and spike protein enzyme immunoassays and microneutralization. Results: Among 16 cases, 11 (69%) had health care exposure and 5 (31%) were relatives of a known case; 13 (81%) were symptomatic, and 7 (44%) died. Genome sequencing of MERS-CoV from 13 cases revealed 3 transmissible deletions associated with clinical illness during the outbreak. Deletion variant sequences were epidemiologically clustered and linked to a common transmission chain. Interviews and sera were collected from 2 surviving cases, 23 household contacts, and 278 health care contacts; 1 (50%) case, 2 (9%) household contacts, and 3 (1%) health care contacts tested seropositive. Conclusions: The MERS-CoV deletion variants retained human-to-human transmissibility and caused clinical illness in infected persons despite accumulated mutations. Serology suggested limited transmission beyond that detected during the initial outbreak investigation.