The United States is currently experiencing a "quad-demic," a term used to describe the simultaneous surge of four illnesses, particularly COVID-19, influenza, respiratory syncytial virus (RSV), and norovirus.
Nationally, the test positivity rate for influenza increased to 18.8%. COVID-19 test positivity remained relatively stable at 6.6%, and RSV positivity rates fell to 8.9%, according to data from the Centers for Disease Control and Prevention (CDC).
Norovirus, also known as stomach flu, surged by about 36% in December 2024 than the same period in 2023. It also increased by nearly 50% than the average in the previous decade, according to All Care Health.
Flu activity is particularly high or very high across 33 states and Washington D.C. Of those, flu levels were highest in Mississippi, Oklahoma, and Texas, the Walgreens Flu Index reported.
Why Is the Quad-Demic Happening?
The overlap of these viruses during winter is not unusual. Colder months typically see increased transmission due to indoor gatherings and weakened immune defenses. However, this season's levels are particularly high largely due to post-pandemic immunity gaps and low vaccination coverage, which has left many people vulnerable.
As of Nov. 9, only 35% of US adults received the new flu vaccine, and nearly 18% got the new COVID-19 vaccines.
How Can Americans Stay Safe?
To stay safe during the ongoing "quad-demic" of COVID-19, flu, RSV, and norovirus, health officials recommend taking preventive measures such as staying up to date with vaccines through getting annual flu shots and updated boosters. Unfortunately, there is no vaccine for norovirus.
Hygiene practices also play a vital role in preventing the spread of all four illnesses. Frequent handwashing with soap and water for at least 20 seconds is especially effective against norovirus, which is resistant to most hand sanitizers.
Washing your hands after using the bathroom, before eating or preparing food, and after coughing or sneezing can help reduce your risk. Additionally, clean high-touch surfaces like doorknobs, light switches, and countertops regularly with appropriate cleaning products to minimize contamination.
Other protective habits include wearing a well-fitted mask, such as an N95 or KN95, especially in crowded indoor spaces. This helps reduce exposure to respiratory droplets that spread COVID-19, flu, and RSV.
