What is the evidence on post-exposure treatments and vaccine efficacy for airborne Ebola and Marburg exposure in animal models?

The short version: VSV-based vaccines completely protected monkeys against aerosol Ebola and Marburg, but post-exposure treatments only prolonged survival, not prevented death.

The key study on vaccine efficacy used a recombinant vesicular stomatitis virus (VSV) platform. Three cynomolgus macaques vaccinated with VSV expressing Zaire Ebola glycoprotein (GP) and four vaccinated with VSV expressing Marburg GP were all completely protected against a lethal aerosol challenge of 1000 plaque-forming units [3]. They showed no clinical disease and no detectable virus after challenge. All five unvaccinated controls died within 6-13 days [3]. This is a small study (9 total animals) but the result was clear and the challenge route matches your question.

The post-exposure treatment evidence is weaker. Interferon-β given after infection prolonged survival in rhesus macaques but did not prevent death. In one Ebola experiment, treated animals lived an average of 13.8 days versus about 6-8 days for controls [1]. A Marburg experiment had one survivor out of the group [1]. The drug AVI-7288, a synthetic antisense molecule, showed a clear dose-response in nonhuman primates: 0% survival at 0 mg, rising to 100% at 20 mg and 30 mg doses [4]. But this was tested against injection challenge, not aerosol, and the human safety data came from only 30 healthy volunteers [4].

The evidence gap is significant. The vaccine study used only one challenge dose and one timing. The post-exposure studies did not use aerosol exposure. No study compared vaccinated-then-aerosol-challenged animals to naturally immune animals. The immune correlates from human outbreaks show that early antibody and T-cell responses predict survival, but neutralizing antibody levels alone do not [2].

My call: the VSV vaccine platform shows strong efficacy against aerosol challenge in a small primate model, but the evidence base is too thin to generalize to humans or to different exposure doses. Post-exposure treatments show partial benefit at best, with no aerosol-specific data. Confidence: moderate for vaccine efficacy in this narrow model, low for post-exposure treatments against airborne exposure.