Flu hospitalizations declined for the first time in several weeks.

Respiratory virus activity continues to remain elevated across the United States but there may be some signs that a peak has been reached for at least one virus, newly updated federal data shows.

As of Friday, "high" or "very high" levels of respiratory illness activity -- defined as people visiting a health care provider with symptoms including cough and fever -- were seen in 35 states in addition to New York City and the District of Columbia, according to the Centers for Disease Control and Prevention, down from 38 earlier this week.

Emergency department visits with diagnosed influenza, COVID-19 and RSV remain high, but all three conditions saw a decrease over the last week. The CDC, however, said this is may due to "holiday-related healthcare seeking behavior and will be monitored."

For the week ending Jan. 6, weekly COVID hospitalizations rose to 35,801. This marks the ninth straight week of increases, but remains lower than hospitalizations recorded at the same time last year.

Nearly 40% of all counties in the U.S. are in the medium category for hospital admission levels, meaning hospitals are seeing 10.0 to 19.9 new admissions for COVID-19 per 100,000 people in the past week.

Those aged 65 and older have the highest rate of weekly COVID hospitalizations by age group followed by those between ages 50 and 64, according to the CDC.

The rise of COVID-19 hospitalizations may be partly due to the spread of the JN.1 variant, which makes up an estimated 61.6% of cases in the U.S. as of Jan. 6.

JN.1 has mutations that may make it either more transmissible or more likely to evade the immune system, the CDC says, but there is no evidence that it causes different symptoms or more severe cases.

Nationally, COVID-19 wastewater viral activity levels are very high, typically an early sign of an increase in cases. There are indications, however, that wastewater activity levels may be slowing in the Midwest and Northeast, the CDC says.

Although influenza activity remains high and key indicators have been increasing for several weeks, the number of weekly new hospital admissions slightly decreased to 18,506, according to CDC data.

"CDC will continue to monitor for a second period of increased influenza activity that often occurs after the winter holidays," the federal health agency wrote on its website.

The CDC estimates that there have been at least 14 million illnesses, 150,000 hospitalizations and 9,400 deaths from flu so far this season. Adults over 65 have the highest rates of flu hospitalizations.

Meanwhile RSV hospitalizations appear to be remaining stable, with a very slight increase in the weekly hospitalization rate from 3.6 per 100,000 the week ending Dec. 16 to 3.7 per 100,000 for the week ending Dec. 23, the last week of complete CDC data.

Unlike with COVID and flu, RSV hospitalizations are highest among children aged 4 and younger followed by adults aged 65 and older.

Vaccines are available for COVID, flu and RSV, but the CDC says "the percent of the population reporting receipt of COVID-19, influenza, and RSV vaccines remains low for adults."

As of Friday, just 21.4% of adults aged 18 and older and have received the updated COVID vaccine, CDC data shows. Additionally, 46.8% of adults have received the flu vaccine. Meanwhile, just 20.1% of adults aged 60 and older have received the RSV vaccine, which was rolled out for the first time this season.