New cases are finally on the decline after a surge of COVID-19, respiratory syncytial virus, and influenza across the country. And while some experts say this decrease in new cases could signal the end of the "tripledemic," others warn that "we are still very much in the throes of winter."

COVID-19, RSV, and flu cases are declining

As of Jan. 18, the seven-day case average for COVID-19 was 47,459, marking a 23.9% decrease from the previous week, according to CDC's COVID-19 data tracker. Similarly, the seven-day hospitalization average for Jan. 10-16 was 5,014, a 16.4% decline from the previous week.

While CDC estimates project a higher number of flu cases for the 2022-2023 flu season than previous years, CDC's Jan. 20 FluView report showed a decline in flu activity around the country.

For the week ending Jan. 14, reports of influenza-like illnesses (ILI) declined to low or minimal levels in many states.

So far, there have 16,602 laboratory-confirmed ILI-associated hospitalizations reported between Oct. 1, 2022, and Jan. 14, 2023. For the week ending Jan. 14, the weekly hospitalization rate was 0.8 per 100,000 population.

On Friday, CDC reported that ED visits for COVID-19, RSV, and flu seem to have peaked in early December.

"It's possible the decline might have been even greater without the mingling in the holidays," said Barbara Mahon, a CDC official who oversees the response to the coronavirus and other respiratory viruses. "Things don't look as bad as they did a few weeks or a few months ago, but we are still very much in the throes of winter."

Is the 'tripledemic' over?

While the declining cases suggest the "tripledemic" may have already peaked, many experts warn that there could be additional increases in flu—which can have two peaks—and RSV cases this spring.In addition, the highly transmissible XBB.1.5 subvariant, which currently accounts for half of all new U.S. infections, could cause another spike in COVID-19 infections.

Meanwhile, hospital executives are grappling with an overwhelmed workforce while navigating the unpredictable patterns of these diseases.

"We have almost three full years of going nonstop, of surges, peaks, downward slopes, getting to a valley," said Cathy Bennett, president and CEO of the New Jersey Hospital Association. "It's rinse, wash, repeat."

Still, the United States is now better prepared to handle COVID-19 surges because most people have developed some level of immunity through previous infections or the COVID-19 vaccines.

"As awful as omicron was, it left in its wake a tremendous amount of immunity," said Jennifer Nuzzo, an epidemiologist at Brown University School of Public Health.

Notably, almost three quarters of patients admitted to Mass General Brigham with COVID-19 during the most recent peak tested positive for the virus after being admitted for other reasons. While these cases still require hospitals to isolate patients to prevent the spread, doctors say they do not drain as many clinical resources.

"This is all good news overall," said Erica Shenoy, Mass General Brigham's medical director of infection control. "One question we all have is, 'Where is this going? Will we settle into a typical respiratory season where things will settle out?'"

While influenza is known for being unpredictable, experts monitoring the virus say it seems to be following a similar pattern to previous flu seasons, with an early start and an early decline.

According to CDC, the number of outpatient visits with respiratory illness has decreased below baseline levels in many areas of the country, including the Upper Midwest, Great Plains and south central United States.

"Now the question is: Are we going to have a typical spring or a late season influenza B surge?" saidScott Hensley, a microbiologist who tracks flu viruses at the University of Pennsylvania's Perelman School of Medicine. (Nirappil, Washington Post, 1/22; Bean, Becker's Hospital Review, 1/20 [1]; Bean, Becker's Hospital Review, 1/20 [2])