"These COVID-19 hospitalizations are devastating for patients, their families, and health care providers," KFF officials said. "The hospitalizations are also costing taxpayer-funded public insurance programs and the workers and businesses paying health insurance premiums."

Indeed, patients themselves are only paying a fraction of the costs of hospitalizations. According to KFF's estimate, the average out-of-pocket cost was just $1,300, though that number varies based on the patient's health care coverage.

The highest monthly cost totals were in August ($4.0 billion) and September ($3.5 billion), as the Delta variant surged throughout the country. Yet KFF officials say their $13.8 billion estimate is a "ballpark figure" and "likely an understatement of the cost burden from preventable treatment of COVID-19 among unvaccinated adults." The estimate, for example, does not include the cost of outpatient treatment. Additionally, new studies estimate the average hospitalization cost of one unvaccinated patient at substantially higher than $20,000.

As of Jan. 11, 2022, with the Omicron variant surging after the holidays, 63% of the United States population was fully vaccinated, according to The New York Times, with a daily average of more than 738,000 new cases and 135,559 hospitalizations. More than 1,650 people were still dying from COVID-19 daily.