This was a retrospective study. While not the most accurate and well supported way to conduct a study, due to the effects of recall bias, it was really the only way to gain the data that was presented in the report. There isn't really anything new about the style of research.
The study was published in BMC Infectious Diseases, a peer-reviewed journal on the prevention, diagnoisis, and management of infectious disease. The journal seems to be genrally well respected.
The data acquired in this study can be used not only for improvement in policies and training for healthcare workers, but also to examine the risk factors for the disease. One example is the age and gender disparities in those nfected. These could be explained by the typical age and gender of healthcare workers, but could also show a trend in risk when coupled with patient data. The data on the districts and their infection rates can be used to help pinpoint the origin of infection.
In the case of this study, the vulnerable population examined was healthcare workers in Sierra Leone during the outbreak. These workers were found to be at a significant level of risk for transmission for a number of reasons. These include proximity to the virus (due to the occupation), lack of training in the area of infection control, and cultural factors (such as prevalence of self-medication and home management of illness). Nurses as a whole were most affected, with over half of the infected members.
The study was funded by the WHO Country Office for Sierra leone.
This study examined the risk of acquiring Ebola Virus Disease (EVD) by healthcare workers in the setting of general hospitals and isolation units. By looking retrospectively at the Ebola Outbreak in Sierra Leone, the relative levels of risk to healthcare workers were computed and compared. The reasoning for these levels was also examined through interviews of surviving workers and the families/associates/colleagues of the deceased workers. The interviews reviewed common actions (and lack there of) for affected workers. This revealed certain themes that should be visited when reveising/creating hospital infection prevention and control policies.
At least one further study has been conducted using this data. A more focussed paper on the Kenema District in Sierra Leone was written, addressing the staggering number of cases with infected healthcare workers. The paper is titled "Facors Underlying Ebola Virus Infection Among healthcare Workers, Kenema, Sierra Leone, 2014-2015." The paper reached similar conlusions as the original one, with a need for better practices in infection control and prevention.