SARS-CoV-2 infection characteristics among students and staff in a large high school COVID-19 outbreak and secondary transmission in households.

Background: SARS-CoV-2 clinical presentation is associated with the patients' age group. Overall, young individuals present higher proportions of asymptomatic or mild COVID-19 infection, compared to adults. Data on secondary COVID-19 transmission in households, according to the cases' age group, are accumulating. Methods: We performed a follow-up cohort study including all COVID-19 real-time polymerase chain reaction (RT-PCR)-confirmed cases (adolescent students and school staff) diagnosed in an epidemiological investigation of a large high school outbreak. We compared the adolescent and adult groups regarding clinical symptoms, time to negative COVID-19 RT-PCR tests, and infection transmission in households. Results: The study population included 817 persons. The confirmed COVID-19 RT-PCR outbreak cases (n = 178) were followed (students aged 12-19 years, median age 14 years, n = 153, school staff aged 24-67 years, median age 39 years, n = 25) and the cases' household close contacts (n = 639) were tested. The adolescents had lower symptomatic infection rates, shorter time to negative COVID-19 RT-PCR tests, and lower transmission rates to household members, compared to the adults. The general transmission rate among household contacts was 13.5%, (86/639) ranging from 8.6% in asymptomatic students' contacts to 27.3% in symptomatic staff contacts. COVID-19 transmission rates were significantly higher in contacts of symptomatic cases compared to asymptomatic cases (odds ratio: 2.06, 95% CI 1.26-3.4) and higher in adults compared to adolescents (odds ratio: 2.69, 95% CI 1.43-4.89). Conclusions: Adolescents and adults diagnosed in an outbreak investigation differ as to COVID-19 clinical presentation and transmission. As adolescents may show mild or no symptoms, COVID-19 prevention in school settings is challenging. Implementing nonpharmaceutical measures and promoting vaccination programs in eligible staff and students should be considered.

Claustral neurons projecting to frontal cortex restrict opioid consumption.

The synthetic opioid fentanyl is a major contributor to the current opioid addiction crisis. We report that claustral neurons projecting to the frontal cortex limit oral fentanyl self-administration in mice. We found that fentanyl transcriptionally activates frontal-projecting claustrum neurons. These neurons also exhibit a unique suppression of Ca2+ activity upon initiation of bouts of fentanyl consumption. Optogenetic stimulation of frontal-projecting claustral neurons, intervening in this suppression, decreased bouts of fentanyl consumption. In contrast, constitutive inhibition of frontal-projecting claustral neurons in the context of a novel, group-housed self-administration procedure increased fentanyl bout consumption. This same manipulation also sensitized conditioned-place preference for fentanyl and enhanced the representation of fentanyl experience in the frontal cortex. Together, our results indicate that claustrum neurons exert inhibitory control over frontal cortical neurons to restrict oral fentanyl intake. Upregulation of activity in the claustro-frontal projection may be a promising strategy for reducing human opioid addiction.