Director Catherine Hughes said the foundation was “hardly a media company”.

“To have this happen at a time when we’re literally about to roll out the COVID vaccination,it almost seems like Facebook is having an impact on our COVID vaccine rollout,which is just unbelievable,” she said.

“We have been kept completely in the dark. There is no message on our page,telling us what’s going on. All the content on our page we’d spent hours scheduling has been completely removed.”

In contrast,a prominent anti-vaccination page remained fully functional. Other fake news pages including those sharing far-right conspiracy articles were also still active,according to Gizmodo.

Removing legitimate news sources during a pandemic left space for unreliable news,conspiracy theories and clickbait to fill that gap,Dr Khorshid said.

“This is extremely irresponsible and dangerous behaviour from one of the biggest organisations in the world,” he said.

University of Sydney vaccine expert Professor Julie Leask said the timing of Facebook’s mass blocking “couldn’t be worse”.

“Three days before our COVID-19 vaccine rollout,Australians using Facebook as their primary source of news can no longer get access to credible information about vaccination from news organisations and some government and public health organisation pages,” she said.

“This is the very time we rely on people accessing vaccine information easily,from their preferred platform.”

Science and Technology Australia was among several health science organisations whose Facebook pages remained bare on Thursday evening.

STA chief executive Misha Schubert said without reliable scientific evidence available on the platform,misinformation could creep in.

“It is crucial,especially amid a pandemic and a bushfire season,that Australians can access expert advice from trusted science organisations across the country,” Ms Schubert said.

The Peter Doherty Institute for Infection and Immunity,which is doing key research on COVID-19,saw its Facebook page stripped of posts,alongside medical research institution the Burnet Institute.

Burnet chief executive Professor Brendan Crabb AC said:“Any sudden change to quality health information flow at any time,but most especially in the midst of a health crisis,is deeply unethical and damaging. It should be met with the sustained contempt it deserves.”