Flu spikes

Influenza-like illness hits a second peak

All things influenza

This special edition of Outbreak Outlook examines an unexpected turn in this year's flu season. Influenza activity is rebounding aggressively, with outpatient influenza-like illness (ILI) now surpassing its January peak to hit 7.0%.

In the past 22 years (i.e., dating back to the 2002-2003) season, only four other seasons have seen a peak that high. And although there are a few years with a double peak, only the 2019-2020 season was comparable in intensity.

(Note: these plots are interactive when viewed in a browser. That functionality does not work in email, so I recommend opening this post in your browser.)

Complicating matters, federal health data is still suffering from interference.

Last week, outpatient influenza data was missing, so I visited the websites of all 50 state health departments to round it up. That data was later brought back online, but then CDC’s main data repository (data.cdc.gov) was taken down. For the second week in a row, I was back to rounding up data by hand.

While data.cdc.gov is back online, key datasets—including HIV statistics—are still missing from the repository. These disruptions are very troubling, not just because they undermine data reliability but because they're happening just as we're weathering unusual flu patterns.

With that in mind, let’s look at the data.

---

Trends by region

Most of the country is still experiencing high or very high levels of influenza activity, and many states have hit outpatient ILI numbers that exceed those seen around the turn of the New Year.

The Southeast is experiencing particularly intense activity, with several states reporting very high levels of both outpatient visits and emergency department utilization. The coastal Mid-Atlantic region is also seeing elevated activity, with some areas reporting outpatient ILI percentages above 10%, which again are some of the highest numbers we have seen all season.

In the Northeast, activity is also high but it does vary by location, with urban states generally showing higher rates than rural states. Emergency department are particularly busy along the I-95 corridor, where multiple locations are reporting ED visit percentages above 7%.

The Midwest is also seeing an uptick in activity, particularly in the Upper Midwest where some areas (e.g., Minnesota) are reporting emergency department visit rates reaching 10%. The southern portions of the Midwest show moderate but increasing activity levels.

The Western region is more mixed, with the Pacific Northwest showing the highest activity in the region. Mountain states generally report lower levels of both outpatient ILI and emergency department visits, though activity is increasing in some areas. The Southwest shows moderate activity with signs of recent increases.

Wastewater concentration, often a leading indicator, does not show signs of slowing. The South, Midwest and Northeast are all seeing marked increases. Only the Western region is stable.

---

Trends by age

As usual, children under 4 years old are experiencing the highest rates of illness at 16.2% ILI, a marked increase from 14.4% the previous week. School-age children and young adults (5-24 years) also show high activity at 11.0%, up from 9.0% last week.

Working-age adults (25-49 years) are experiencing moderate activity at 5.9%, while older adults show progressively lower rates, with those 50-64 years at 4.3% and those 65 and older at 2.7%. All age groups are seeing increases compared to the previous week.

Unfortunately, these increases in children are translating into severe illness. School-age kids have seen a significant spike in emergency department visits for influenza, overtaking the 0-4 age group.

---

Is the rebound in activity because of H5N1?

If you are wondering whether the new spike in activity is due to H5N1, you are not alone. But I checked, and there is no evidence of this.

Public health laboratories ran additional testing on 2,150 influenza A specimens last week, and none of them were H5N1. Circulating subtypes are evenly split between H1N1 and H3N2.

There is also no sign of extensive H5 in wastewater.

---

Why are eggs so expensive?

The spike in human influenza activity is not due to H5N1, but the price of eggs sure is! The Federal government tracks retail egg prices, and the latest data (through December 2024) shows that the price of eggs is climbing toward last year’s high water mark of $4.82.

These impacts are due to outbreaks in commercial flocks, and they will likely continue. Late winter into early spring is peak season for H5N1 in birds. We will likely continue to see high prices for another month or two, at least.

COVID-19

Covid-19 also continues to circulate. Wastewater inched back up again this past week after a couple weeks of declines.

The highest rates continue to be in the Midwest, followed by the South. Most regions are seeing stable or slightly increased wastewater concentrations, which suggests we will continue to see elevated activity in the weeks ahead.

Severe illness is not increasing nationally, however. Emergency department visits for Covid-19 held steady this past week at 0.9% of all ED visits. The rate of people hospitalized for Covid-19 decreased slightly, to 3.6 hospitalizations per 100,000 people.

---

RSV & Other Bugs

RSV activity continues its steady decline nationwide, though still above off-season levels.

Two causes of cold- and flu-like symptoms (human coronaviruses and human metapneumovirus) are both high but on the declining side of the curve. Other bugs are fairly low right now.

---

Norovirus

Data are back after the pause last week and, as expected, things have not dramatically improved. Test positivity is 21.5%, which is marginally better than it was a few weeks ago but still extremely high. The Midwest and Northeast are being hit particularly hard, but rates are very high across the country.

Source: CDC

---

Food recalls

The following foods are being recalled because they are contaminated. Please check your cupboards and throw out any of these items:

New:

• Blue Ridge Beef Natural Mix [for dogs] (more info). While not for human consumption, humans may be infected with Salmonella if they do not adequately wash their hands or contaminated surfaces after handling the product.

• Wegman’s fully cooked breaded chicken nuggets (more info)

Previously reported:

• Casa Mamita frozen chicken and cheese taquitos (more info)

• Wicklow Gold Cheddar Cheeses (more info)

• Blue Ridge Beef Kitten mix [for Cats] (more info)

• If you have food allergies, you may wish to review these FDA safety alerts and USDA alerts for foods with undeclared allergens.

---

In other news

• Health programs funded by the United States have been halted by President Trump’s 90-day pause on foreign aid and stop work orders. Critical lifesaving medications and medical supplies, for everything from HIV/AIDS to treatment for diarrhea, are no longer reaching people. Thousands of healthcare and aid workers who carry out these programs have already lost their jobs, including two-thirds of the staff of the President’s Malaria Initiative, which benefits more than 700 million people every year.

• Several government websites providing information and data on public health have been removed following President Trump’s recent executive orders, including datasets on HIV/AIDS transmission and the health behaviors of teenagers. It is not clear which pages will be made available to the public again. These datasets are used by public health professionals and academics across the country to research trends and properly tailor and target public health programming and interventions.

---

Get detailed, state-specific public health updates with regional editions—available to paid subscribers. Stay informed where it matters most to you!

---