Viral illness surges amid ‘quad-demic’ in US

According to Centers for Disease Control and Prevention (CDC) data, viral illnesses have increased in the United States in an ongoing “quad-demic” by early 2025, citing three respiratory viruses and one gastrointestinal disease.

The number of people diagnosed with COVID-19, influenza or respiratory syncytial virus (RSV), including norovirus, has increased, the CDC said in a new update Friday.

Emergency department visits are “high” for RSV and influenza diagnoses nationally. Compared to the fall figures, visits “improved” due to the COVID-19 contract

Positive tests for influenza rose to 18.8 percent, while positive tests for COVID-19 held a “stable” pace at 6.6 percent, according to CDC data.

Positive tests for RSV dropped to 8.9 percent.

“Nationally, levels of viral activity in wastewater for COVID-19 and influenza A remain high,” the CDC wrote in the update. “Moderate levels of viral activity in national RSV wastewater.”

“Covid predictions for the next two weeks suggest that emergency department visits will remain at lower levels than in previous winter seasons,” the CDC said. “Influenza forecasts indicate that emergency department visits will remain at high to very high levels for the next two weeks.”

Cases of norovirus have also increased, with the CDC reporting 91 outbreaks in December. There is no vaccine available to prevent individuals from gastrointestinal illness.

Norovirus causes diarrhea and vomiting, according to the CDC.

“It is sometimes called ‘stomach flu’ or ‘stomach bug’. However, norovirus illness is not related to the flu,” the CDC says. “The flu is caused by the influenza virus. Norovirus causes acute gastroenteritis, an inflammation of the stomach or intestines.