HM Prison Belmarsh
Supporters of the WikiLeaks founder claim coronavirus is spreading through Belmarsh prison, where Assange is being held.
The former EastEnders star spent six months visiting HMP Belmarsh prison for his new ITV show.
Stephen Yaxley-Lennon had been handed a nine month term.
The whistleblower has been moved to a medical ward in prison.
He refused to appear for a second day.
Anderson is Assange's first visitor as he spends 50 weeks at the south-east London prison.
Trials have already shown positive results.