Flow interactions lead to self-organized flight formations disrupted by self-amplifying waves.

Collectively locomoting animals are often viewed as analogous to states of matter in that group-level phenomena emerge from individual-level interactions. Applying this framework to fish schools and bird flocks must account for visco-inertial flows as mediators of the physical interactions. Motivated by linear flight formations, here we show that pairwise flow interactions tend to promote crystalline or lattice-like arrangements, but such order is disrupted by unstably growing positional waves.

Effectiveness of Monoclonal Antibody Therapy for Preventing COVID-19 Hospitalization and Mortality in a Statewide Population.

Background: Monoclonal antibody (MAB) treatments for COVID-19 received Emergency Use Authorization in the United States.

Methods: We used surveillance data from Rhode Island to conduct a retrospective, statewide cohort study to estimate the effectiveness of MABs for preventing hospitalization and death during periods when Alpha and Delta variants were predominant.

Results: From 1/17/2021-10/26/2021, 285 long-term congregate care (LTCC) residents and 3,113 non-congregate patients met our eligibility criteria and received MAB; they were matched to 285 and 6,226 controls, respectively.

Effectiveness Associated With Vaccination After COVID-19 Recovery in Preventing Reinfection.

Importance: The benefit of vaccination for preventing reinfection among individuals who have been previously infected with SARS-CoV-2 is largely unknown.

Objective: To obtain population-based estimates of the probability of SARS-CoV-2 reinfection and the effectiveness associated with vaccination after recovery from COVID-19.

Design, Setting, And Participants: This cohort study used Rhode Island statewide surveillance data from March 1, 2020, to December 9, 2021, on COVID-19 vaccinations, laboratory-confirmed cases, hospitalizations, and fatalities to conduct a population-based, retrospective study during periods when wild type, Alpha, and Delta strains of SARS-CoV-2 were predominant.