Force of Infection is trusted by 45,000+ readers to track flu, Covid-19, RSV, norovirus, food recalls, and more. Paid subscribers receive regional editions during flu season (October–March) and Covid-19 reports in the summer. Free subscribers receive the national edition during flu season.

Influenza-like illness

We seem to be moving out of the doldrums: there were some decreases this week that I didn’t have to squint to see. Outpatient visits for influenza-like illness decreased down to 3.8%. Rates are lowest in the Northeast, where outpatient ILI has dipped down to about 3%, and only one state is still at high levels of activity. The other regions are all clustered around 4%.

Outpatient ILI rates dropped notably for those aged 0-4, from 11.7% to 10.3%. Similarly, for those aged 5-24, rates dropped from to 8.4% to 7.2%. Older age groups showed smaller declines.

More severe illness is also showing signs of improvement. And ED visits for flu dipped from 3.6% down to 2.5%. Hospitalizations similarly moved from 3.0 hospitalizations down to 2.5 per 100,000.

Flu B continues to account for a greater proportion of cases, amounting to 63.8% of clinical lab samples, and 30.3% of public health lab samples.

Hang in there, dear readers — we are nearing the end of flu season.

COVID-19

Activity continues its slow decline across most of the country. ED visits dipped a bit, to 0.5% nationally. Wastewater activity is low and declining. Hospitalizations are also fairly low and declining, at about 1 hospitalization per 100,000 people nationally.

The Midwest continues to fare a bit worse than other regions, though it is closing that gap as rates fall. ED visits in the region dipped to ~0.7%, with decreases reported in all states. Wastewater activity in the region has declined to moderate levels as well. Things are quiet in most of the West. ED visits there are the lowest in the country, at 0.4%, and very low wastewater activity.

The South and Northeast are right in between: both at about 0.6% ED visits. Wastewater activity is low and stable in the South, and has decreased to moderate levels in the Northeast. However, hospitalizations remain a bit high in the Northeast, at 2.5 hospitalizations per 100,000 people.

RSV & Other Bugs

RSV: RSV just will not quit. It’s been an oddly late year. RSV test positivity continues to rise, and is now up 9.1%, which is starting to approach last year’s peak of 11%. ED visits held steady at 0.6%.

Rates remain highest in the Midwest and West, with ED visits at about 0.7%, and lowest in the South at ~0.6%.

As usual for RSV, infants and young children are most affected by severe illness. For infants under the age of 1, ED visits are quite elevated at 5.0%. Trips the ED are also high, but decreased this past week to, 4.1% for those aged 1-4 years.

Hospitalizations remain elevated at 3.0 hospitalizations per 100,000 people for the total population. Hospitalizations peaked for infants under 1 last week at 43.9 hospitalizations per 100,000, and dipped this past week to 32.3. Rates have also decreased for those aged 1-4, declining to 17.9 this past week.

Other bugs:

• Several causes of respiratory illnesses are circulating widely right now. Human coronaviruses have peaked and remain very high.
• Human metapneumovirus is rising steeply. Last year, it peaked in mid-April; it looks like that peak might come a bit sooner this year.
• Adenovirus is back up to fairly high levels.
• Parainfluenza and rhinoviruses/enteroviruses are low.

Norovirus

Stomach bug season persists. Norovirus test positivity remains very high, at 13.7%, though there has been a slight decrease the past couple weeks. There will likely be several more weeks of heightened levels. Rates tend to really decline in late spring.

Things are particularly rough in the Midwest, where rates continue to be on an overall rising trendline, with test positivity at a very high 17.1%. In the South, rates are stagnating at high levels, around 11.1%.

Some good news in the Northeast: test positivity dropped from a seasonal peak of 15.3% two weeks ago down to 10.6% last week. That is still quite elevated, but a welcome improvement nonetheless. While less dramatic, rates also decreased a bit in the West, down to 9.3% this past week.

Food recalls

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

New:

• Expanded recall of frozen chicken fried rice products, sold under multiple brand names: Trader Joe’s, Ajinomoto, Kroger, Ling Ling, and Tai Pei, due to possible glass shards (more info)

Previously Reported:

• Great Value (sold at Walmart) Cottage Cheese (more info)
• Elite Treats Chicken Chips (for dogs). These may be contaminated with salmonella, which poses a health risk not only for dogs, but also for humans who handle the product or contaminated surfaces (more info).
• Bremer Family Size Italian Meatballs (frozen, ready-to-eat) (more info)
• Multiple flavors of cream cheese under the Made Fresh Salads, Inc. label (more info)
• Gerber Arrowroot biscuits (more info)
• Organic chia seeds sold by Navitas Organics (more info)

In other news

• Measles outbreaks continue across U.S. There have now been 1,281 confirmed cases of measles so far this year. Cases have been reported in 31 states, with the largest number of cases reported in South Carolina (>650 cases), followed by Utah (>180), Florida (>100), and Texas (>90). Staff with the US CDC will be deployed to South Carolina in the coming days to assist with outbreak response there, though it does appear that new cases in the state are finally slowing down.
• Avian flu case reported in Cambodia. A case of highly pathogenic avian influenza, H5N1, has been reported in a man in Cambodia, marking the country’s first reported case this year. The man is now recovered after having been hospitalized. Spillovers of H5N1 from animals into humans are rare, but are watched closely by public health experts because they both tend to be quite serious (with high fatality rates) and because of the risk that the virus might mutate to spread well from person-to-person and launch flu pandemic. No signs of that with this case, however. None of the man’s contacts have developed illness.
• Research participation opportunity. My research group is seeking state and local public health professionals to participate in two upcoming research studies. The first study explores how influenza forecasts can be presented more clearly so that decision-makers can accurately interpret what a forecast is telling them. The second study aims to establish performance standards for influenza forecasts so that decision-makers can feel confident acting on forecast results. Participation involves either a virtual focus group or a series of online questionnaires, depending on the study. If you are interested in learning more, please fill out this form so a member of the research team can follow up with you.