Royal Cornwall Hospitals NHS Trust was caring for 20 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 14 was up from 18 on the same day the previous week.
There were seven beds occupied by Covid-19 patients four weeks ago in Royal Cornwall Hospitals NHS Trust.
Across England there were 6,720 people in hospital with Covid as of December 14, with 150 of them in mechanical ventilation beds.
The number of Covid-19 patients hospitalised nationally has increased by 34% in the last four weeks, while the number on mechanical ventilators has increased by 23%.
The figures also show that 13 new Covid patients were admitted to hospital in Royal Cornwall Hospitals NHS Trust in the week to December 12. This was down from 19 in the previous seven days.