Outbreak Outlook - National - March 24

Respiratory Diseases

Influenza-like illness

Influenza-like illness continues to ease. During the week ending March 15, 3.9% of visits to the doctor were for fever and cough or sore throat (also known as outpatient ILI), down from 4.3% the week prior.

Regular readers may recall that we had two peaks this season, one at 6.8% and the other at 7.8%. So, we have come a long way, but we are still working towards the 3% threshold that marks the end of flu season.

All age groups are enjoying improvements, with outpatient ILI in the 0-4 year olds declining to 10.4%, down from this season's high of 18.1%. Outpatient ILI in school age kids is at 6.2%, and all of the older age groups are 3.5% and under. More severe illness, as measured by the percentage of emergency department visits that are for influenza, has also declined substantially across all age groups. However, emergency department visits for influenza remain elevated compared to the off-season.

The proportion of activity that is flu B is increasing, now at 6%. I can attest—it hit my house this week. We diagnosed through an at-home antigen test that looks for SARS-CoV-2, flu A, and flu B. I found the test to be pretty handy, though a little expensive. Flu B activity generally increases in the spring, which is exactly what we are seeing. It tends to be milder than flu A.

There's no question that this was a remarkable flu season. Deaths from pneumonia and influenza far exceeded the last few seasons (as shown below). Hospitalizations for influenza were high as well. In some ways, we are fortunate that we had a quiet Covid-19 winter season, because the combined burden on the healthcare system could have been even more substantial.

Source: CDC

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COVID-19

Covid-19 is hitting a lull in many places in the country, with low and declining wastewater and low rates of severe illness. Nevertheless, activity is still high in more than a dozen states.

Nationally, wastewater activity held roughly steady at a moderate rate this past week. Activity remains moderate, but is increasing in the Midwest and South. Activity is low and stable in the Northeast and declining in the West.

Emergency department visits are low at 0.7%, with no significant change in the past week. Since January, national ED visits for Covid-19 have declined by half.

Hospitalizations are low and continue to slowly decline, falling to 2.6 hospitalizations per 100,000 people.

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Other Bugs

Several other causes of cold and flu-like symptoms are circulating:

• Human metapneumovirus has sharply increased and is now at its highest point this season.

• Human coronaviruses appear to have peaked a few weeks ago, and while rates are still high, they are on the way down.

• Adenovirus is picking up a bit again, after peaking near the end of the year.

• Rhinoviruses/enteroviruses remain low, but have increased a bit this fast few weeks.

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Norovirus

Some slightly good news - norovirus activity dipped a bit in the past couple weeks, down to 17% test positivity. This is still very high, but it is lower than it has been December. Rates are lowest in the West, and the South and Midwest are roughly tied for first place.

Source: CDC

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Food recalls

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

New:

• Lean Cuisine and Stouffer’s frozen meals (more info)

• Savage Pet Cat Food Chicken [for cats]. Due to potential contamination with H5N1 - this poses a health risk for cats as well as potentially to humans as well. (more info)

• SeaBear Smoked Clam Chowder and Alehouse Clam Chowder (more info)

Previously reported:

• Enoki mushrooms sold under Daily Veggies brand (more info)

• Hot pot sauce sold under Wangshihe brand (more info)

• Prepared vegetables sold at Tokyo Central/Marukai stores in California (more info)

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

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In other news

• There is just one more edition left for this season. The last free national edition will be published next week. Paid subscribers will continue to receive the national edition through the spring and summer months. The winter publication schedule will resume in October. As a reminder, I am also offering twice-weekly measles updates to paid subscribers.

  

  Photo by Mark Tegethoff on Unsplash