may not be possible to achieve, as virus replicates in the upper respiratory tract even in the presence of specific antibodies, similarly to other respiratory viruses. Because dromedary camels do not show severe clinical signs upon MERS-CoV infection, vaccination of dromedaries should primarily aim to reduce virus excretion to prevent virus spreading. Young dromedaries excrete more infectious MERS-CoV than adults (8, 15, 16), so young animals should be vaccinated first. Our results reveal that MVA-S vaccination of young dromedary camels may significantly reduce infectious MERS-CoV excreted from the nose. Two major advantages of the orthopoxvirus-based vector used in our study include its capacity to induce protective immunity in the presence of preexisting (e.g., maternal) antibodies (32) and the observation that MVA-specific antibodies cross-neutralize camelpox virus, revealing the potential dual use of this candidate MERS-CoV vaccine in dromedaries. Dromedary camels vaccinated with conventional vaccinia virus showed no clinical signs upon challenge with camelpox virus, whereas control animals developed typical symptoms of generalized camelpox (33). The MVA-S vectored vaccine may also be tested for protection of humans at risk, such as health care workers and people in regular contact with camels.

No abstract

Super-spreading occurs when a single patient infects a disproportionate number of contacts. The 2015 MERS-CoV, 2003 SARS-CoV, and to a lesser extent 2014-15 Ebola virus outbreaks were driven by super-spreaders. We summarize documented super-spreading in these outbreaks, explore contributing factors, and suggest studies to better understand super-spreading.

The emergence of the H7N9 influenza virus in humans in Eastern China has raised concerns that a new influenza pandemic could occur. Here, we used a ferret model to evaluate the infectivity and transmissibility of A/Shanghai/2/2013 (SH2), a human H7N9 virus isolate. This virus replicated in the upper and lower respiratory tracts of the ferrets and was shed at high titers for 6 to 7 days, with ferrets showing relatively mild clinical signs. SH2 was efficiently transmitted between ferrets via direct contact, but less efficiently by airborne exposure. Pigs were productively infected by SH2 and shed virus for 6 days but were unable to transmit the virus to naïve pigs or ferrets. Under appropriate conditions, human-to-human transmission of the H7N9 virus may be possible.