The WHO backed up the Chinese governments line stating there was 'no clear evidence of human-to-human transmission'.
They said there was no clear evidence of human-to-human transmission because they had not seen any clear evidence of human-to-human transmission. They can't make China give them all their data and they won't say they have evidence for something when they don't.
Meanwhile on 10-11 January they put up detailed technical guidance for all countries, based on the assumption that human-to-human transmission via droplets and close contact was likely, because that's how respiratory pathogens usually spread.
Dr Maria Van Kerkhove, WHO's technical lead on the virus, addressed this in the last press briefing:
With regard to the human-to-human transmission question, right from the start, from the first notification that we received on 31st December, given that this was a cluster of pneumonia - I'm a MERS specialist so my background is in coronaviruses and influenza so I immediately thought, given that it's a respiratory pathogen, that of course there may be human-to-human transmission.
So initially when we started to put together our technical guidance for our member states we put guidance that focused on how this virus could be transmitted and what we focused on was droplet and contact transmission, which is how respiratory pathogens are spread. Also within our infection prevention and control guidance we put out a special provision for healthcare workers who are focused on conducting aerosol-generating procedures in which we put in place recommendations for airborne transmission. That guidance is still in effect.
The guidance that we put up was on 10th and 11th of January because there were five or six technical guidance materials that were put up on the web which were open to everyone. We also shared this guidance package which included surveillance guidance on how to find cases, laboratory guidance on how to detect cases, infection prevention and control, how to prevent infections, particularly in healthcare settings because, given our past experience with MERS and with SARS, we immediately thought that you could have transmission. in healthcare facilities, you could have amplification events in healthcare facilities and potential superspreading events.
(if this doesn't start at the right time, go to 21:52)