Colorado instituted stay-at-home orders to reduce community transmission of SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19). To inform public health messaging and measures that could be used after reopening, persons with laboratory-confirmed COVID-19 during March 9-26 from nine Colorado counties comprising approximately 80% of the state's population † (Adams, Arapahoe, Boulder, Denver, Douglas, El Paso, Jefferson, Larimer, and Weld) were asked about possible exposures to SARS-CoV-2 before implementation of stay-at-home orders. Among 1,738 persons meeting the inclusion criteria § in the Colorado Electronic Disease Surveillance System, 600 were randomly selected and interviewed using a standardized questionnaire by telephone. Data collection during April 10-30 included information about demographic characteristics, occupations, and selected activities in the 2 weeks preceding symptom onset. During the period examined, SARS-CoV-2 molecular testing was widely available in Colorado; community transmission was documented before implementation of the stay-at-home order. At least three attempts were made to contact all selected patients or their proxy (for deceased patients, minors, and persons unable to be interviewed [e.g., those with dementia]) on at least 2 separate days, at different times of day. Data were entered into a Research Electronic Data Capture (version 9.5.13; Vanderbilt University) database, and descriptive analyses used R statistical software (version 3.6.3; The R Foundation). Among the 600 randomly selected COVID-19 patients, 133 (22%) were unreachable, 57 (10%) declined to participate, and 46 (8%) were ineligible (e.g., the onset date was too early or the patient was asymptomatic), leaving 364 (61%) participants. The median age of participants was 50 years (interquartile range = 34-64 years), and 187 (51%) were male. Overall, 206 (57%) participants identified as non-Hispanic white and 75 (21%) as Hispanic. Among all participants, 345 (95%) reported having health insurance, 128 (35%) were hospitalized and 18 (5%) died. Occupations reported by the 264 (73%) * These authors contributed equally. † https://demography.dola.colorado.gov/population/population-totals-counties/. § Inclusion criteria consisted of laboratory-confirmed SARS-CoV-2 infection, presence of ≥1 symptom to establish illness onset date, and known hospitalization status.

Following nerve stimulation, there are two distinct phases of Ca 2+-dependent neurotransmitter release: a fast, synchronous release phase, and a prolonged, asynchronous release phase. Each of these phases is tightly regulated and mediated by distinct mechanisms. Synaptotagmin 1 is the major Ca 2+ sensor that triggers fast, synchronous neurotransmitter release upon Ca 2+ binding by its C 2 A and C 2 B domains. It has also been implicated in the inhibition of asynchronous neurotransmitter release, as blocking Ca 2+ binding by the C 2 A domain of synaptotagmin 1 results in increased asynchronous release. However, the mutation used to block Ca 2+ binding in the previous experiments (aspartate to asparagine mutations, syt D-N) had the unintended side effect of mimicking Ca 2+ binding, raising the possibility that the increase in asynchronous release was directly caused by ostensibly constitutive Ca 2+ binding. Thus, rather than modulating an asynchronous sensor, syt D-N may be mimicking one. To directly test the C 2 A inhibition hypothesis, we utilized an alternate C 2 A mutation that we designed to block Ca 2+ binding without mimicking it (an aspartate to glutamate mutation, syt D-E). Analysis of both the original syt D-N mutation and our alternate syt D-E mutation at the Drosophila neuromuscular junction showed differential effects on asynchronous release, as well as on synchronous release and the frequency of spontaneous release. Importantly, we found that asynchronous release is not increased in the syt D-E mutant. Thus, our work provides new mechanistic insight into synaptotagmin 1 function during Ca 2 +-evoked synaptic transmission and demonstrates that Ca 2+ binding by the C 2 A domain of synaptotagmin 1 does not inhibit asynchronous neurotransmitter release in vivo. Significance statement This study provides mechanistic insights into synaptotagmin function during asynchronous neurotransmitter release and supports a dramatically different hypothesis regarding the mechanisms triggering asynchronous vesicle fusion. Using two distinct C 2 A mutations that block Ca 2+ binding, we report opposing effects on synchronous, spontaneous, and asynchronous neurotransmitter release. Importantly, our data demonstrate that Ca 2+ binding by the C 2 A

A better understanding of SARS-CoV-2 transmission from children and adolescents is crucial for informing public health mitigation strategies. We conducted a retrospective cohort study among household contacts of primary cases defined as children and adolescents aged 7-19 years with laboratory evidence of SARS-CoV-2 infection acquired during an overnight camp outbreak. Among household contacts, we defined secondary cases using the Council of State and Territorial Epidemiologists definition. Among 526 household contacts of 224 primary cases, 48 secondary cases were identified, corresponding to a secondary attack rate of 9% (95% confidence interval [CI], 7%-12%). Our findings show that children and adolescents can transmit SARS-CoV-2 to adult contacts and other children in a household setting.

AbstractFollowing nerve stimulation, there are two distinct phases of Ca2+-dependent neurotransmitter release: a fast, synchronous release phase, and a prolonged, asynchronous release phase. Each of these phases is tightly regulated and mediated by distinct mechanisms. Synaptotagmin 1 is the major Ca2+ sensor that triggers fast, synchronous neurotransmitter release upon Ca2+ binding by its C2A and C2B domains. It has also been implicated in the inhibition of asynchronous neurotransmitter release, as blocking Ca2+ binding by the C2A domain of synaptotagmin 1 results in increased asynchronous release. However, the mutation used to block Ca2+ binding in the previous experiments (aspartate to asparagine mutations, sytD-N) had the unintended side effect of mimicking Ca2+ binding, raising the possibility that the increase in asynchronous release was an artifact of ostensibly constitutive Ca2+ binding. To directly test this C2A inhibition hypothesis, we utilized an alternate C2A mutation that we designed to block Ca2+ binding without mimicking it (an aspartate to glutamate mutation, sytD-E). Analysis of both the original sytD-N mutation and our alternate sytD-E mutation at the Drosophila neuromuscular junction showed differential effects on asynchronous release, as well as on synchronous release and the frequency of spontaneous release. Importantly, we found that asynchronous release is not increased in the sytD-E mutant. Thus, our work provides new mechanistic insight into synaptotagmin 1 function during Ca2+-evoked synaptic transmission and demonstrates that Ca2+ binding by the C2A domain of synaptotagmin 1 does not inhibit asynchronous neurotransmitter release in vivo.Significance statementThis study provides mechanistic insights into synaptotagmin function during asynchronous neurotransmitter release and supports a dramatically different hypothesis regarding the mechanisms triggering asynchronous vesicle fusion. Using two distinct C2A mutations that block Ca2+ binding, we report opposing effects on synchronous, spontaneous, and asynchronous neurotransmitter release. Importantly, our data demonstrate that Ca2+ binding by the C2A domain of synaptotagmin does not regulate asynchronous release and thus disprove the current inhibition hypothesis. We propose a spatial competition hypothesis to explain these seemingly discordant results of the differing C2A Ca2+ binding mutations.

Despite causing numerous large outbreaks in the 20th century, few isolates of o’nyong nyong virus (ONNV) have been fully sequenced. Here, we report the complete genome sequence of an isolate of ONNV obtained from a febrile patient in northwest Uganda in 2017, designated ONNV UVRI0804.