President Trump backed hydroxychloroquine for weeks and publicly asked whether Americans should inject themselves with disinfectants or put ultraviolet lights — which can cause burns and break human DNA, which leads to cancer — inside their bodies.
Mr. Pattison said he had a staff of only five, although the agency subscribes to NewsGuard, a service that hunts for new rumors springing up on the internet. His staff examines NewsGuard alerts, consults medical experts, posts accurate information on the W.H.O. website and then calls its contacts at social media agencies and asks them to link to it.
In contrast, collaborating with Wikipedia “is like having an army to work with,” he said.
Wikipedia has about 5,200 Covid-related articles in 174 languages, Mr. Merkley said. More than 82,000 contributors have written or edited them, including 3,000 who worked on the main article in English Wikipedia.
Because some contributors insert errors or “make malicious changes,” he said, there are several levels of safeguards. Some pages can be “locked” and cannot be changed until one of more than 200 volunteer editors on WikiProject Covid-19, many of whom are doctors or academics, review it.
More than 1,100 volunteers have set alerts to notify them when any page they are interested in is changed. And, if necessary, changes by any account that has existed for less than 30 days can be blocked.
The W.H.O. also works with Google, but in a different way, Mr. Pattison said. For instance, Google analysts alerted his team that searches for an unfamiliar product as a Covid cure were peaking in Peru. The W.H.O. looked at the product, realized it was a type of bleach and alerted Google.
“They gave us $50 million worth of free ads on Google,” he said.
The agency posted public service announcements that read, “Learn the truth about Covid and chlorine.”