Viruses spiking in the United States as peak season arrives in winter

According to the Centers for Disease Control and Prevention (CDC), several viruses, including seasonal flu, stomach flu, COVID-19, and RSV, are rising in the United States and are expected to increase during the winter months.

The CDC reported in its weekly update that flu activity is high nationwide, and more people are visiting emergency rooms. The number of people seeking healthcare for respiratory illnesses is increasing.

So far this season, the CDC estimates there have been at least 5.3 million illnesses, 63,000 hospitalizations, and 2,700 deaths from the flu. Last year, there were 470,000 hospitalizations and 28,000 deaths from the flu.

During the last week of the year, public health labs reported 1,254 viruses, 1,234 of which were influenza A and 20 of which were influenza B. The CDC noted that flu test positivity is now at 18.7%.

The highest flu activity is in Arizona, Utah, Texas, Oklahoma, Nebraska, Florida, Georgia, Kentucky, Tennessee, and New Hampshire. The lowest levels are in North Dakota, Vermont, and Maine. The CDC advises everyone aged 6 months and older to get an annual flu vaccine.

“This is clearly the season,” said Dr. Eduardo Azziz-Baumgartner from the CDC’s Influenza Division. This year’s flu wave is arriving later than in the previous two years. After the COVID-19 pandemic, flu cases spiked earlier than before.

Flu trends this season resemble those from 2019 to 2020, which also peaked around New Year’s. “In December 2022, we saw a large spike in flu cases, but this year is significantly higher,” said Sara Hottman from Oregon Health & Science University Hospital.

Last year, the combination of RSV, flu, and COVID created a public health crisis, but we do not expect that this year. The CDC refers to this situation as a “tripledemic.”

COVID-19 cases are also increasing in most areas, and RSV levels are very high, especially among young children. The positivity rate for COVID-19 tests is now 7.1%, and for RSV, it is 12.8%.

COVID-19 levels are monitored through wastewater testing and emergency department visits. The CDC no longer tracks total COVID-19 cases, although some states still report data. States that do collect data typically do not count most at-home tests.

The CDC predicts that COVID-19 cases will continue to rise in the coming weeks, as they typically do in winter. Experts believe the upcoming 2024-2025 COVID-19 vaccine will work well against current variants. Most current COVID-19 infections in the U.S. are from the XEC variant, similar to earlier strains.

Wastewater levels for COVID-19, influenza A, and RSV are currently moderate. The CDC is also noting an increase in norovirus, which causes stomach flu and is the top cause of vomiting and diarrhea in the U.S. Norovirus leads to about 2,500 outbreaks each year, mainly spread by infected individuals, including on cruise ships.

Additionally, the CDC is monitoring the Type A H5N1 bird flu, with 66 human cases reported in the U.S. last year, 37 of them in California.