The U.S Centers for Disease Control and Prevention (CDC) warns of a surge in respiratory illnesses across the country, with 15 states facing "high" or "very high" levels of infection.

Respiratory illnesses like flu, COVID-19, respiratory syncytial virus (RSV) infection and common cold exhibit "very high" levels of prevalence in Louisiana and South Carolina, followed by "high levels" in California, New Mexico, Mississippi, Alabama, Tennessee, Georgia and New York City. The activity levels of infections are measured based on the percentage of visits to enrolled outpatient healthcare providers or emergency departments for fever, cough or sore throat.

"The amount of respiratory illness (fever plus cough or sore throat) causing people to seek healthcare is elevated or increasing across most areas of the country. CDC is actively following up with health departments in these communities," the CDC said in a news release.

According to a CDC report, 22,513 people were hospitalized from COVID-19 in the week ending Dec. 2, the highest level since February end. The rate of COVID-related hospitalization is highest among the children and the elderly. However, reports indicate that the cases remain low compared to the numbers during the same time last year.

The rate of flu-related hospitalizations has spiked, with a total of 5,753 patients admitted in the week ending Dec. 2, compared to 4,268 in the previous week. Meanwhile, there is a slight dip in hospitalizations from RSV infection – 2.4 per 100,000 for the week ending Dec. 2 compared to 2.5 per 100,000 the previous week.

"Everything that we're hearing about it is not any new virus or new pathogen, it is the common things that we see every season that perhaps coming together. The preventive things are all the same, you know, stay home if you're sick, wash your hands, cough into your sleeve, don't rub your eyes, nose and mouth, get up to date on the vaccinations," said Dr. Philip Huang, director of Dallas County Health and Human Services.

Huang recommends using a mask when in contact with people who are at a higher risk of severe illness or when in a crowded area with poor ventilation.

The data on vaccination indicate there are more takers for flu vaccine compared to COVID-19 and RSV vaccines. Records show that 7.7% of children, 17.2% of people above 18, and 36% of people above 65 have received an updated COVID-19 vaccine. Around 16% above 60 years took the RSV vaccine. Notably, a higher percentage – 41.6% of children, 40.8% above 18 and 66.6% above 65 years – have taken flu shots.