Cornwall Partnership Trust was caring for 54 coronavirus patients in hospital as of Tuesday, figures show.
NHS England data shows the number of people being treated in hospital for Covid-19 by 8am on December 21 was up from 30 on the same day the previous week.
There were five beds occupied by Covid-19 patients four weeks ago in Cornwall Partnership NHS Foundation Trust.
Across England there were 8,643 people in hospital with Covid as of December 21, with 174 of them in mechanical ventilation beds.
The number of Covid-19 patients hospitalised nationally has increased by 88% in the last four weeks, while the number on mechanical ventilators has increased by 49%.
The figures also show that 48 new Covid patients were admitted to hospital in Cornwall Partnership NHS Foundation Trust in the week to December 19. This was up from 22 in the previous seven days.