E-Mail UNIVERSITY PARK, Pa. -- When healthcare workers become ill during a disease outbreak, overall case counts and mortality rates may significantly increase, according to a new model created by researchers at Penn State. The findings may help to improve interventions that aim to mitigate the effects of outbreaks such as COVID-19. "Each year dozens of potentially lethal outbreaks affect populations around the world. For example, Ebola ravaged western Africa in 2014; Zika damaged lives in the Americas in 2015; and now we are in the midst of a worldwide pandemic -- COVID-19," said Katriona Shea, professor of biology and Alumni Professor in the Biological Sciences, Penn State. "Healthcare workers are essential to providing care during such outbreaks. Yet, their exposure to the diseases they treat means they too may become victims of the outbreak. Conventional epidemic models do not usually consider this important driver of quality of care, and may thus underestimate epidemic burdens."