Slowly but surely we’re moving through the 2023-2024 respiratory season. I’m also adding a measles section to the State of Affairs because… well… here we are in the 21st century.

Let’s dig in.

Influenza-like illnesses: Moderately stubborn

The rate at which people are going to the doctor with a fever, cough, or sore throat is stubborn—stalling at a very inconvenient rate. But a two- or three-hump season is very normal (i.e., in pre-pandemic times). This could stretch out to April or May.

Outpatient Respiratory Illness Visits (Source: CDC; Annotated by YLE)

Increased activity is driven by our kiddos. Outpatient visits among 0-24 year olds continue to increase, while visits among other age groups are receding.

Percent of Outpatient Visits for Respiratory Illness by Age Group (Source: CDC; Annotated by YLE)

Covid-19: High

Covid-19 wastewater levels are high nationally. And, in fact, higher than they were this time last year. Although national rates are declining, the South has a very weird pattern. We don’t know why.

Wastewater Viral Activity Levels (Source: CDC; Annotated by YLE)

Covid-19 hospitalization admissions are stalling after a nice decline. We remain at fewer hospitalizations than last year.

(Source: CDC; Annotated by YLE)

CDC and WHO are paying attention to another highly mutated variant in South Africa. However, there have only been 9 cases, with no impact on wastewater or hospitalization trends. This seems like a dud, which is great news. No other huge variants are on the horizon; JN continues to be king.

Flu: Still high and stabilizing

The rate of hospitalizations due to flu remained stable compared to last week. Flu can stretch out, sometimes to even May, so this is unsurprising. It’s not too late to get your flu shot!

Weekly rate of laboratory-confirmed influenza hospitalizations among cases of all ages, 2014-15 to 2023-24, MMWR Week 6(Source: CDC; Annotated by YLE)

RSV: Plummeting

RSV continues to go down nationally. It’s clear we’ve hit our season’s peak.

Percent positive RSV tests in the United States, by week (Source: CDC)

More good news with RSV: many babies (40%) got monoclonal antibodies this winter. This could certainly be improved, but given the rough access issues, it is a decent start.

Measles: More outbreaks

This may be a bad year for measles (see why in my previous post), so many epidemiologists are carefully watching the data.

So far, in 2024, we’ve had 20 cases across 11 states. This is about twice as many cases as this time last year.

Data is delayed, so this doesn’t include a few recent cases making the news:

• Ohio reported its second case of the year, which exposed a number of people at a grocery store.
• Washington also reported a case, which is likely from international travel.
• An elementary school outbreak in Florida has infected six so far. Florida allows non-medical vaccine exemptions, which has increased since 2021. And Florida is below the herd immunity threshold, with ~90% vaccination rate (we need 95%). The worst part is the Florida Surgeon General’s letter to parents ignoring standards of practice and suggesting schools and parents should “choose their own adventure” with measles containment. It is egregious. Expect a full YLE post on this soon, but here is my initial reaction. I wasn’t happy.

Other things I’m paying attention to:

• E. coli outbreak linked to raw milk cheese.
  • At least 10 cases across 4 states, with 4 people hospitalized and one developing a serious kidney condition.
  • There is a reason we pasteurize dairy, people. This method was developed 160 years ago to reduce the risk of bacterial contamination and foodborne illnesses. Please don’t fall for wellness misinformation. Raw milk has zero additional health benefits.
• Next week, ACIP—CDC’s external scientific advisory board—is meeting to discuss all vaccines. I will report back on Covid-19 and RSV. I have two big questions:
  • What is the spring plan for Covid-19 vaccines? U.K. (and local U.S. jurisdictions like Los Angeles) have announced that older people can get a spring Covid-19 vaccine. I assume this is coming for the U.S.
  • What does the safety profile look like for the older adult RSV vaccine? Some questions were brought up during clinical trials. We really need real-world data.

Bottom line

This respiratory season continues to march on with few surprises. Unfortunately, it’s happening amidst a backdrop of misinformation, which will increasingly cause a mess, like measles and e-coli outbreaks.

Vaccines. Masks. Ventilation. Tests. Treatment. Isolation. We can do things to keep ourselves healthy. For high-risk folks, this may also mean changing Spring Break plans to avoid a measles outbreak or two.

Love, YLE

“Your Local Epidemiologist (YLE)” is written by Dr. Katelyn Jetelina, M.P.H. Ph.D.—an epidemiologist, wife. During the day, she is a senior scientific consultant to several organizations, including CDC. At night, she writes this newsletter. Her main goal is to “translate” the ever-evolving public health world so that people will be well-equipped to make evidence-based decisions. This newsletter is free, thanks to the generous support of fellow YLE community members. To support this effort, subscribe below: