The United States has seen an uptick in flu and COVID-19 cases amid holidays, and health experts are concerned about the increasing health risks brought by the simultaneous spread of respiratory illnesses.

The amount of respiratory illnesses causing people to seek healthcare is elevated or increasing across most areas of the country, according to the U.S. Centers for Disease Control and Prevention (CDC).

This rise is attributed to several factors, including holiday gatherings, a high number of unvaccinated individuals, and the emergence of a new, potentially more transmissible variant of the coronavirus, according to health experts.

Seasonal influenza activity is elevated in the United States, and continues to increase in most parts of the country, the latest CDC data showed.

There have been at least 5.3 million illnesses, 54,000 hospitalizations, and 3,200 deaths from flu in the United States so far this season, according to CDC estimates.

The number of weekly flu hospital admissions continues to increase, with over 9,800 patients admitted to hospitals with flu in the week ending Dec. 16, according to the CDC.

A total of 14 flu-associated pediatric deaths have been reported in the country this season.

Nationally, laboratory test positivity for flu and emergency department visits due to flu are increasing, according to the CDC.