Force of Infection

Force of Infection is now on the summer schedule, meaning national Outbreak Outlook updates are only available to paid subscribers. The winter schedule, including the free national version, will resume in October. To continue receiving reports during the summer, please upgrade to paid.

Influenza-like illness

Seasonal influenza remains low at this time of year. Trips to the doctor for symptoms like fever, cough, and sore throat (referred to as outpatient influenza or ILI) are at 1.2%, which is about as low as it gets. 

The West, which is slightly above the national average, is still trending downward and is now at 1.4%, from 1.6% a few weeks ago. The Northeast is holding steady at 1.1%. The Midwest is experiencing the least ILI, below 1%. 

Severe illness remains low. Visits to the emergency department (ED) continue to hover around 0.2%. The West is at 0.3%, but still trending down. The weekly influenza hospitalization rate continues to be low at 0.1 per 100,000. The Midwest is the region experiencing the least percentage of severe illness, with hospitalizations nearing zero. Michigan and Minnesota contributed to this improvement.

Outpatient ILI for infants and young children under the age of 4 years is trending down towards 4%, while older kids and young adults remain steady at 2%. Activity for older adults (50+ years) is staying below 1%.

Covid-19

Activity for Covid-19 remains low across the country, with emergency department (ED) visits at 0.1% and hospitalizations are minimal. 

Force of Infection is now on the summer schedule, meaning national Outbreak Outlook updates are only available to paid subscribers. The winter schedule, including the free national version, will resume in October. To continue receiving reports during the summer, please upgrade to paid.

Influenza-like illness

Seasonal influenza remains very low in this off-season period. Trips to the doctor for symptoms like fever, cough, and sore throat (referred to as outpatient influenza-like illness or ILI) dropped a further notch and are now at 1.4% (from 1.6% last week). 

The West, which remains above the national average at 1.8%, experienced the most noticeable drop in ILI. All other regions also trended downward, with the Midwest lower than 1%.

Force of Infection is now on the summer schedule, meaning national Outbreak Outlook updates are only available to paid subscribers. The winter schedule, including the free national version, will resume in October. To continue receiving reports during the summer, please upgrade to paid.

Influenza-like illness

Seasonal influenza remains steady in this off-season phase. Trips to the doctor for symptoms like fever, cough, and sore throat (referred to as outpatient influenza-like illness or ILI) are holding at 1.6%, which is the same as last week.

At the regional level, the West is a touch higher at 2% ILI, while the Midwest is the lowest at 1%. 

Force of Infection is now on the summer schedule, meaning national Outbreak Outlook updates are only available to paid subscribers. The winter schedule, including the free national version, will resume in October. To continue receiving reports during the summer, please upgrade to paid.

Influenza-like illness

Seasonal influenza activity continues to trend down during this off-peak period. Trips to the doctor for symptoms like fever, cough and sore throat (referred to as influenza-like illness or ILI) have decreased slightly to 1.6% (down from last week’s 1.8%). 

At the national level, just 0.2% of visits to the emergency department (ED) are for influenza. ED visit rates are highest for young people between the ages of 5 and 17 years (0.7%) and lowest for adults 65 and older (0.1%). The weekly hospitalization rate last week was 0.1 per 100,000 people, down from 0.3 per 100,000 the previous week. 

Among infants and young children (ages 0–4), 5.2% of doctor visits are for fever, cough, and sore throat (influenza-like illness). For older children and young adults (ages 5–24), that figure is 2.3%. Both percentages have decreased slightly compared to last week.

Two influenza-associated deaths were reported this past week, for a total of 174 deaths this season. (Note: death reporting is often delayed, so these deaths may not necessarily be recent). Approximately 85% of reported pediatric deaths this season, according to the Centers for Diseases Control and Prevention, have occurred in either unvaccinated or not fully vaccinated children. 

Covid-19

There are some very early and preliminary indications of increased activity in a few Southern states (e.g., Florida, Texas). Activity is very low, so small increases are of little consequence. I mention it only because this time of year I begin to monitor for the first signs of the summer wave, and it's those states that typically tick up first. It could just be normal fluctuation. To 'call' the start of the wave, I need to see a few consecutive weeks of increase, over an expanding geographic area. We're not there yet.

It is that time of the year again! In the United States, Memorial Day weekend marks the unofficial start of the summer. That means longer days, beach trips, kids splashing in pools, picnics, barbecues, and lots of time outdoors. But staying safe is just as important as having fun, which is why every year I share a few first aid videos to remind readers of the basics. I specifically chose these videos because they are only 2-5 minutes long, so you can get through the entire set in about 15 minutes.

When an emergency happens, many of us freeze. It is a natural response. Our brains are hard-wired for the “fight, flight, freeze” response, an automatic reaction to perceived threats that can make it hard to think clearly. But learning a few basic skills ahead of time, can help you stay calm and feel more prepared if something

Force of Infection is now on the summer schedule, meaning national Outbreak Outlook updates are only available to paid subscribers. The winter schedule, including the free national version, will resume in October. To continue receiving reports during the summer, please upgrade to paid.

Influenza-like illness

We continue to navigate this off-season as expected. Trips to the doctor for fever, cough and sore throat (known as influenza-like illness, or ILI) are stable at 1.8%. 

At the regional level, the Midwest is reporting the lowest levels of ILI at 1%, which is nevertheless a slight notch higher than last week (0.9%; this is not a meaningful difference). The West continues to be a tad higher than the national average, but holds steady at 2.1%. 

Force of Infection is now on the summer schedule, meaning national Outbreak Outlook updates are only available to paid subscribers. The winter schedule, including the free national version, will resume in October. To continue receiving reports during the summer, please upgrade to paid.

Influenza-like illness

The off-season is in full swing. Trips to the doctor for fever, cough and sore throat (known as influenza-like illness, or ILI) remain steady at 1.8%. 

At the regional level, the Midwest is reporting the lowest levels of ILI at 0.9%, while the West continues to decline

This is the second installation in a series about respiratory viruses and their complexities. The first essay explained less common viruses like human metapneumovirus and adenovirus. Today, we're taking a deeper look at disease surveillance.

Why don’t I know what I have?

If you go to the doctor or hospital with what feels like a “cold,” there’s a set of decisions happening behind the scenes about whether to test you, and for what.

In most outpatient settings, testing is usually “targeted.” This means you might get a single test (for example, just for influenza), or a small “triplex” panel that checks for the most common viruses: SARS-CoV-2, flu, and RSV. These are the pathogens where a diagnosis can directly affect care or

A new Covid-19 variant has been making headlines lately, and this one has an unusual name. BA.3.2, nicknamed "cicada", has been detected in at least 25 U.S. states and 23 countries. Here's what we know so far.

Why "cicada"?

Cicadas are famous for spending years underground before emerging in enormous numbers, sometimes after 13 or 17 years of dormancy. BA.3.2 follows a loosely similar pattern: it was first identified in South Africa in November 2024, circulated at very low levels for over a year largely under the radar, and then emerged more forcefully in Europe last fall before

Force is growing, and so is the team. I'm excited to welcome Gage Moreno, PhD, as a contributing writer. Like our upcoming move to a standalone website, expanding the team is part of the plan to make this publication more valuable to you over the long term. This is the first explainer in a two-part series; Part II will cover how epidemiologists track these pathogens, and what future technologies might improve surveillance. -Caitlin

If you’ve ever been sick with “a cold,” yet tested negative for flu and Covid-19, you’ve already bumped up against a hidden world of viruses.

“A cold” isn’t a single illness it’s a label used for dozens of respiratory pathogens that circulate every year, most of which are rarely tested for. Even though they are largely invisible to patients, these viruses cause real illness, drive outbreaks, and shape

Yesterday, the U.S. CDC issued a Health Alert Network (HAN) advisory about New World screwworm cases on the Mexico side of the Texas-Mexico border. New World screwworm is primarily a disease of livestock, though humans can become infected. There are currently no human or animal cases in the United States, though it is an encroaching threat.

Against the backdrop of resurgent pertussis and measles, a recent infant botulism outbreak, and a changing vaccine schedule, screwworm feels like a distant concern. Yet clinicians have not received a HAN on these more pressing issues. The last advisory covering a disease with U.S. cases was in March, three HANs ago.

This is the gap I want to close with FOI Clinical, a new outbreak monitoring service I’m launching. There is no quick, easy way for front-line clinicians like pediatricians, family doctors, or emergency physicians to get a recurring,