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Respiratory Diseases

ILI

Influenza-like illness (ILI) remained stable this week at 4.4% of doctor visits for symptoms of fever plus cough or sore throat, continuing to exceed the national baseline of 2.9%. This means flu season continues to chug along, with very high ILI activity reported in areas spanning from Wyoming to New Mexico to Ohio to D.C. to New York City.

By age: There was an uptick in ILI visits among adults aged 25-49, 50-64, and those 65 and older, coming several weeks after initial increases in the kid age groups. However, rates in those age groups are all below 5%, so not terrible. On the bright side, there was finally a decrease in the 0-4 years age group and stability in the 5-24 years age group, so I expect that adults will improve in weeks ahead.

By region: Regional trends are mixed.

• The Midwest saw an increase in ILI. Many states in the region are now experiencing high levels of activity.
• Parts of the West also saw increases in ILI activity. However, the West still has the lowest levels of ILI in the country.
• The South saw a mix of increases and decreases, though most states remain in the high category.
• The Northeast is doing pretty well, with steady declines in ILI. However, New York City remains very high.

By severity: Nationally, hospitalization rates due to influenza saw a slight increase, marking one of the highest for this time of year (that part is important, for this time of year) in recent records, thanks to this second peak we are experiencing. Influenza-associated pediatric deaths also rose, with nine new reports this week, bringing the total for this season to 91. 

Canada: Influenza activity is holding steady in Canada, and outpatient ILI activity is still within expected levels for this time of year. The regions most affected by influenza are Toronto and Vancouver, and adults over 65 years old are the age group most affected by influenza. As in the U.S. the number of hospitalizations due to influenza is higher than usual for this time of year because the season is hanging on a little longer, with the highest rates among adults 65 years of age and older and children under 5 years of age.

COVID-19

Good news on the Covid-19 front, at least. New weekly Covid-19 hospitalizations are consistently decreasing, reaching levels last seen in November. All age groups are now seeing a decline in hospitalizations. In addition, emergency department visits and test positivity have been improving.

Some concerning trends that I had noticed in the South have dissipated somewhat, easing my concerns. It’s not a totally uniform improvement — some states in the South are still seeing increases, but I remain hopeful that these trends are merely a temporary fluctuation. Moreover, wastewater concentration is either stable or declining in all regions of the country, which is also a good sign.

Canada: Covid-19 activity in Canada is steady or declining. As of February 20, 2024, four provinces (Quebec, Newfoundland, New Brunswick and Nunavut) reported moderate activity levels and the rest reported low levels. All but Nunavut are decreasing. The JN.1 variant is currently the dominant lineage group in Canada, same as in the U.S. 

RSV

Most of the country is now out of RSV season, with PCR test positivity rates falling below 5%. The only region above this line is the Midwest, but it should see continued improvements in the coming weeks.

Stomach Bugs

At the national level, we continue to advance through peak season. PCR test positivity is 12.3%, up about a point from last week. Test positivity usually peaks in the teens (e.g., 14-16%) around March. Norovirus causes vomiting and diarrhea. It’s sometimes called the stomach bug or the 24 hour flu, but that is a misnomer because it is not related to influenza.

Food recalls

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

New

• None

Previously reported:

• A big recall of Queso Fresco and Cotija Cheese is affecting numerous consumer products: (more info)
• Robitussin Honey CF Max cough syrup products (more info)
• Charcuterie meats sold by Fratelli Beretta and, newly, Busseto (more info)
• Tons of different granola and oatmeal products from Quaker (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

• A sizeable cluster (seven cases) of measles at a Florida elementary school has drawn national attention. Florida Surgeon General Joseph Ladapo issued a letter advising parents to make their own decisions regarding whether to keep their unvaccinated children home from school. This is a departure from the usual handling of measles outbreaks. The letter also did not explicitly recommend the MMR vaccine for people who are unvaccinated.

  • Most children do not receive their first dose of the MMR vaccine until 12-15 months of age (though it can be administered earlier, if needed), and so I worry especially about the impact of these outbreak management decisions on infants.

• Speaking of measles, in my job as a professor I am looking for collaborators at state, tribal, local and territorial health departments for a project aimed at reducing the workload associated with measles response. You do not need to be currently responding to measles to join. If interested, please reply to this email.