US sees a 'quad-demic' of viruses

Test positivity rates for COVID-19, flu, and RSV have remained elevated over the last few weeks, with flu positivity rates being the highest of the three. As of Jan. 18, 25% of flu tests were positive, as well as 8.8% of RSV tests and 6.2% of COVID-19 tests.

Rates of acute respiratory illness (ARI) continue to be moderate to very high in most states. According to CDC, the ARI metric captures a broad range of diagnoses, including common colds to more severe infections, based on ED visits for respiratory illnesses.

When it comes to weekly hospitalization rates, the flu continues to have a significantly higher hospitalization rate than both COVID-19 and RSV, despite hospitalization rates having declined over the last few weeks. As of Jan. 18, the weekly hospitalization rate for the flu was 6.1 per 100,000 people. In comparison, the COVID-19 weekly hospitalization rate was 2 per 100,000 people, and the RSV hospitalization rate was 2.4 per 100,000 people.

"Right now, flu is the driver," said Demetre Daskalakis, who is in charge of CDC's response to respiratory infectious-disease threats. "We obviously have a healthy respect for covid-19 given things can change, but right now, it's not as dominant of a player."

Aside from respiratory viruses, norovirus, a gastrointestinal disease, has also been on the rise across the country. Although norovirus cases typically rise in the winter, doctors said that the rapid increase in cases alongside the respiratory virus season is "atypical."

During the week of Dec. 5, 2024, the latest for which data is available, there were 91 norovirus outbreaks reported. As of Jan. 4, almost 28% of norovirus tests came back positive, a figure that is reportedly a five-year high.

"With norovirus, it is a different strain than what we've seen in past years," said Katie Passaretti, enterprise chief epidemiologist at Atrium Health. "So, some supposition that our usual baseline level of protection in the community might be a little bit lower, and that's adding to the higher number of cases."

According to Scott Roberts, medical director of infection prevention at Yale New Haven Health, while there are fewer patients being hospitalized with respiratory illnesses now compared to the first COVID-19 wave in 2020, it can still be challenging to find beds for patients.

"What we're seeing now is that the hospitals near 100% capacity almost all the time, and when you add an extra 100 patients with respiratory viral disease who otherwise would not be there if this wasn't respiratory viral season, you really tax the system," Roberts said. "And so, we are seeing that at Yale. We're seeing a very full hospital near 100% capacity. We're seeing very full emergency rooms with waits to get into the hospital because of that."

Because of limited capacity and long wait times, doctors are urging patients who may be sick with a respiratory illness to consider a virtual healthcare visit or visit an urgent care center rather than going to a hospital.

At the same time, hospitals are starting to implement visitor restrictions and masking requirements in certain settings to prevent the spread of viruses. For example, Atrium Health has asked its staff and visitors to mask up in areas where there is direct patient care. Yale New Haven Health has also recommended staff wear masking when providing care directly to patients.

Novant Health has increased the level of masking for its staff, including in the ED and around vulnerable patients. The health system has also restricted visitors under the age of 13.

"Children can also often carry viruses and not be as symptomatic as adults, and so we want to be careful about bringing those viral infections into our facilities," said David Priest, Novant's chief safety and quality officer.

Currently, health experts continue to emphasize the importance of vaccination to protect against respiratory illnesses. Other tips to reduce the spread of illnesses include staying home when you're sick and washing your hands thoroughly.

"We really need to help with messaging the importance of these vaccines, because really the best method of prevention is vaccination, and it's always easier to prevent an infection from occurring to begin with than to treat it once it's already occurred, with antivirals, for example," Roberts said.