This piece in the Lancet, authored by Cowling and Yu, discusses issues of Ebola dissemination and means to reduce spread to other countries. Its final paragraph discusses what we do not yet know, but need to learn:
There are several important near-future research needs. Perhaps most urgent is a better understanding of the effectiveness of existing treatment options, including convalescent serum. In the medium term, it is hoped that new vaccines and drugs will be available quickly for human clinical trials and in exposed populations.8 The WHO Ebola Response team has neatly summarised the transmission dynamics and epidemiological characteristics including the reproductive number, incubation period, and case fatality risk in the current Ebola virus outbreak,1 but one important unknown is the proportion of infections that are asymptomatic or mildly symptomatic. If mild infections do occur and are infectious, disease control outside west Africa might be increasingly challenging. However, this scenario is thought to be unlikely.9 One particularly pressing need is for the reassessment of appropriate procedures for infection control, and the potential for the virus to spread via small particle aerosols10 in addition to via contact with infected patients or their bodily fluids. Infection of health-care personnel in west Africa is often attributed to the scarcity of appropriate protective equipment and supplies, or inadequate administrative controls.11, 12 However, the nosocomial cases in Dallas and Madrid have raised the concern that present protocols might not be sufficient to protect health-care personnel fully against infection, particularly if cases are managed in health-care facilities that are not fully prepared.
Readers note: CDC improved its infection control PPE recommendations the evening of Oct 20, making them virtually equivalent or better than the SARS protocols. (SARS spread by the respiratory route.) They now include respiratory droplet precautions. This piece was published online Oct. 21. I believe the current CDC recommendations provide health-care personnel with as good protection as currently achievable using available PPE.