The Department of Disease Control (DDC) said on Monday that between April 16 and 22, 1,088 people with severe condition were admitted to hospitals or an average of 155 per day.
Of the admitted patients, 73 suffered lung inflammation and 35 required ventilators.
This figure is more than double compared to the week of April 9-15, when only 435 patients were admitted and two died from the virus.
Since the beginning of the year, Thailand has seen 6,571 patients being admitted for Covid-19 treatment and 278 dying from the virus.
As of April 22, a total of 144.95 million doses of Covid-19 vaccines have been administered, with 57.23 million being first jabs and 53.73 million second jabs.