Key measures of respiratory virus activity in the United States have been trending down for weeks, and the US Centers for Disease Control and Prevention says the worst of the season may be over – but virus levels still remain elevated across the country.

During the week ending on February 10, flu hospitalization rates were about half of what they were at this season’s peak at the end of December, and Covid-19 hospitalization rates were about a third lower, CDC data shows.

“While the respiratory virus season is likely past its peak, it is definitely not over,” the agency wrote in an update to its website Friday. “There is still a lot of respiratory virus activity, so it’s not time to let our guard down.”

Covid-19 viral levels in wastewater remain high in the US – especially in the South, where levels are twice as high as the rest of the country. Despite the improvements, thousands of people are still being hospitalized with Covid-19: more than 21,000 people during the week ending on February 10, according to the CDC. The latest data from the CDC on Covid-19 deaths is incomplete, but it estimates that there were at least 650 deaths during the week ending February 10.

And overall, the share of medical visits for respiratory illness – with symptoms of a fever, along with a cough or sore throat – has been above baseline since November. Nearly 5% of all outpatient visits were for influenza-like illness in early February, well above the 3% national baseline.

Half of US states had high or very high respiratory virus activity during the week ending on February 10, according to the CDC. Agency forecasts show that Covid-19 infections are probably growing in a dozen states, while flu infections are growing in nine states.

So far this season, there have been fewer hospitalizations for flu, Covid-19 and RSV than there were at this point last season. And this season’s peak week for respiratory virus hospitalizations happened a few weeks later and was slightly lower than last season, CDC data shows.

But flu season can be unpredictable, with “significant” activity continuing through May in some years, the CDC says. And while it’s become less likely now for a Covid-19 illness to lead to severe outcomes than at previous points in the pandemic, the coronavirus continues to be a leading cause of death in the US.

Vaccine uptake is slightly lower than it was at this point in the season last year, and it’s still not too late to get vaccinated against flu and Covid-19, the CDC says. Just about half of the US population has gotten the flu shot this season, while about 22% of adults and 12% of children have gotten the latest Covid-19 shot.

“Vaccination remains the best way to protect yourself and your loved ones against serious outcomes of these viral respiratory illnesses,” the CDC says. “Vaccination is especially important for people at increased risk for severe disease, including infants, older adults, pregnant people, and people with certain disabilities or underlying medical conditions.”

Masking, physical distancing, handwashing and improving airflow can help prevent the spread of respiratory viruses, the CDC says, and testing early in the course of an illness can help ensure that those who need treatment – such as Paxlovid for Covid-19 and Tamiflu for influenza – can get it.