Effects of universal masking on Massachusetts healthcare workers' COVID-19 incidence.

BACKGROUND: Healthcare workers (HCWs) and other essential workers are at risk of occupational infection during the COVID-19 pandemic. Several infection control strategies have been implemented. Evidence shows that universal masking can mitigate COVID-19 infection, though existing research is limited by secular trend bias. AIMS: To investigate the effect of hospital universal masking on COVID-19 incidence among HCWs compared to the general population. METHODS: We compared the 7-day average incidence rates between a Massachusetts (USA) healthcare system and Massachusetts residents statewide. The study period was from 17 March (the date of first incident case in the healthcare system) to 6 May (the date Massachusetts implemented public masking). The healthcare system implemented universal masking on 26 March, we allotted a 5-day lag for effect onset and peak COVID-19 incidence in Massachusetts was 20 April. Thus, we categorized 17-31 March as the pre-intervention phase, 1-20 April the intervention phase and 21 April to 6 May the epidemic decline phase. Temporal incidence trends (i.e. 7-day average slopes) were compared using standardized coefficients from linear regression models. RESULTS: The standardized coefficients were similar between the healthcare system and the state in both the pre-intervention and epidemic decline phases. During the intervention phase, the healthcare system's epidemic slope became negative (standardized ß: -0.68, 95% CI: -1.06 to -0.31), while Massachusetts' slope remained positive (standardized ß: 0.99, 95% CI: 0.94 to 1.05). CONCLUSIONS: Universal masking was associated with a decreasing COVID-19 incidence trend among HCWs, while the infection rate continued to rise in the surrounding community.

VLA-4 blockade suppresses endotoxin-induced uveitis: in vivo evidence for functional integrin up-regulation.

Leukocyte adhesion to the vascular wall is a critical early step in the pathogenesis of inflammatory diseases and is mediated in part by the leukocyte integrin, VLA-4, which binds to endothelial vascular cell adhesion molecule (VCAM) -1. Here, we investigate VLA-4's role in endotoxin-induced uveitis (EIU). At various time points (6-48 h) after EIU induction, the severity of the inflammation was evaluated by quantifying cell and protein content in the aqueous fluid, firm leukocyte adhesion in the retinal vessels, and the number of extravasated leukocytes into the vitreous. Functional activation of VLA-4 in vivo was investigated in our previously introduced autoperfused micro flow chamber assay. Firm adhesion of EIU leukocytes to immobilized VCAM-1 under physiological blood flow conditions was significantly increased compared with normal controls (P<0.05), suggesting an important role for VLA-4 in EIU. VLA-4 blockade in vivo significantly suppressed all uveitis-related inflammatory parameters studied, decreasing the clinical score by 45% (P<0.01), protein content in the aqueous fluid by 21% (P<0.01), retinal leukostasis by 68% (P<0.01), and leukocyte accumulation in the vitreous by 75% (P<0.01). Our data provide novel evidence for functional up-regulation of VLA-4 during EIU and suggest VLA-4 blockade as a promising therapeutic strategy for treatment of acute inflammatory eye diseases.