How it is a lie? People talk a lot about the presence of asymptomatic transmission, but:
1. No one knows for sure if completely asymptomatic people are contagious, and the extent of such contagiousness;
2. People equate asymptomatic with presymptomatic, which is a totally different story;
3. The evidence is at best, inconsistent. There is one case report of a non-contagious "asymptomatic" (reading the paper, the symptoms were there, just not the usual ones), and Singapore contact tracing of a number of completely asymptomatic people did not seem to find infected people in contact with them.
Presymptomatic state is a different matter, and it looks more contagious, but again, a lot of it is speculation, because it's really hard to measure.
This transmission is there. The extent of it is not known.
The conspiracy people say it's because they wanted to protect mask supplies - but most people just blame incompetence.
I can only find one paper by the WHO from 2003 that discusses the effectiveness of masks in reducing transmission of SARS.[1] The paper says that because many different social distancing and hygiene measures were taken at the same time, it is impossible to assess how effective each individual measure was. For example, the abstract states,
> The independent effectiveness of measures to "increase social distance" and wearing masks in public places requires further evaluation.
I found plenty of papers that find that mask use by healthcare workers in hospitals is effective, but that's not the same as what you're claiming.
0 https://www.cdc.gov/coronavirus/2019-ncov/prevent-getting-si...
> There was a point where they told the public that masks don’t help.
Because that was a widespread belief among researchers at the time.
> recently one of their leaders said that “asymptotic transmission is rare” which is a deadly lie.
First, it wasn't a "lie," and using that hyperbolic language is not helpful. Second, there is still a lot of confusion within the scientific community about whether asymptomatic transmission actually is important. Studying transmission is really difficult. Further, the WHO official did not definitively state that asymptomatic transmission is rare. She made it clear that the whole question is very uncertain at the moment - because it is.
> incalculable damage is done by these mixed, inconsistent messages.
The message is mixed because the state of knowledge about a lot of aspects of this virus is uncertain or changing. It's impossible (and undesirable) to be 100% consistent when the state of knowledge changes.
What is actually damaging is that people are attacking the WHO and trying to destroy it, because it hasn't met the impossible standard (omniscience about a novel virus) that the critics are setting. The WHO has done a very difficult job fairly well, and is being most viciously attacked by precisely the country that has had one of the most incompetent responses to the outbreak.
The WHO gives the current state of knowledge, including uncertainties. So in early January, when they didn't know if there was sustained human-to-human transmission of the virus, they said they didn't know, but advised doctors to take precautions to prevent transmission.