Microglial morphology is difficult to quantify. Currently, there are no agreed upon systemic method of quantification of microglial morphology within the healthy brain or in response to an injury. Studies have proposed myriad models of morphological changes in microglial reactivation and recent studies have found sex differences in microglia. To examine changes in the microglia of murine hippocampus, we immunofluorescent identified microglia, in coronally sectioned tissues, using ionized calcium-binding adapter molecule-1 (Iba-1) labeling. We used three methods to examine microglia morphology: mean fluorescence intensity, soma volume, and single-cell tracing. For soma volume and single cell tracing, we reconstructed the 3D microglia in the Neurolucida software and analyzed their morphology using Sholl analysis. We used Alternaria alternata in our environmental chamber to model peripheral allergic inflammation. We found that female microglia increase their cell number and nodes while males did not. We conclude that females are more responsive to Alternaria than males, increasing their cell density and surveillance.

Introduction: Our goal was to quantify healthcare clinician (HCC) absenteeism in the emergency department (ED) during the coronavirus disease 2019 (COVID-19) surge and to identify potential interventions that may mitigate the number of absences.

Methods: This was a retrospective, descriptive record review that included 82 resident physicians, physician assistants, and staff physicians who were scheduled to work more than three clinical shifts during March 2020 in an urban, academic ED that received a high number of coronavirus disease 2019 (COVID-19) patients. Exposure was defined as a healthcare clinician who was not wearing appropriate personal protective equipment (PPE) having contact with a confirmed COVID-19 positive patient in the ED. The main outcome was the number of HCC absences secondary to exposure to or symptoms concerning for COVID-19.

Results: During March 2020, of 82 ED HCCs, 28 (34%) required an absence from clinical duties, totaling 152 absentee calendar days (N = 13 women [46%]; N = 15 men [54%]). Median HCC age was 32 years (interquartile range 28-39), and median number of days absent was four (interquartile range 3-7). While 16 (57%) of the total absences were secondary to a known exposure, 12 (43%) were symptomatic without a known exposure. A total of 25 (89%) absent HCCs received COVID-19 testing (N = 5 positive [20%]; N = 20 negative [80%]) with test results returning in 1-10 days. Eleven (39%) symptomatic HCCs had traveled domestically or internationally in the prior 30 days.

Conclusion: Emergency departments should anticipate substantial HCC absences during the initial surge of a pandemic. Possible interventions to mitigate absences include early and broad use of PPE, planning for many asymptomatic HCC absences secondary to exposures, prioritizing HCC virus testing, and mandating early travel restrictions.