Although influenza-like illness (ILI) activity has been below baseline for weeks now, we are currently seeing a bump in influenza B activity. Unlike influenza A, which typically peaks during the winter months, flu B tends to circulate more in the spring.

Although the absolute number of reported flu B cases is low, the proportion has risen from 10% at the end of the calendar year to nearly 50% more recently. I think we’ll see more flu B in the weeks to come.

The overall level of ILI (influenca-like illness)activity is still below threshold, with 2.3% of visits to outpatient providers for fever and a cough or sore throat. Activity remains highest in children ages 0-4 at 7.4%.

The two jurisdictions with stubbornly elevated levels of overall ILI activity are New York City and Washington, D.C.

In New York City, 5% of visits to the doctor were for ILI. The proportion of influenza positive results that are type B rose again this week, signaling increased activity there (see figure). In Washington D.C., overall ILI activity is at 4%.

Reported influenza cases by type, NYC. Source.

Covid-19 activity is still declining. The number of weekly cases fell to around 121,00 compared to 137,000 the week before. The number of people hospitalized with Covid-19 is also falling. The number of weekly deaths rose slightly to 1,773, likely due to lags in data reporting.

RSV activity is low, but activity in the related virus metapneumovirus is still rising. Adenovirus activity is also still high, as is parainfluenza. In other words, there are still some respiratory pathogens circulating that are worth avoiding, so take advantage of the nicer weather and get some fresh air circulating indoors.

Norovirus activity is still high. It has likely peaked in the southern region according to CDC data, but there is no clear peak yet in the other three regions. Data from multiplex diagnostics company Biofire shows a clearer peak, so I’m hopeful that we’ll round the corner soon.

Before I go on to food recalls, let me just say that I know a lot of families, particularly those with small children, are still struggling with infections even though the winter flu season is ostensibly over. Just in the last week I’ve heard of adenovirus, stomach bugs, strep throat, and COVID-19 in my social network. Hang in there, better times are ahead.

Food recalls:

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

New this week:

• A variety of lettuce and salad kits sold by Revolution Farms in Midwestern states. (more info)

Reported in the last month:

• Raw flour (no brand identified yet). Unbaked flour is a common source of Salmonella food poisoning. Do not consume unbaked flour. (more info)
• Biltmore Smoked Wild Sockeye Salmon with best by dates of April 14. (more info)
• Frozen organic strawberries and tropical fruit mix sold to Costco, Trader Joe’s, Aldi, KeHE, Vital Choice Seafood, and PCC Community Markets. (more info)
• Boneless beef chuck packed in February and sold in many states. (more info)
• If you have food allergies, you may wish to review these FDA safety alerts for foods with undeclared allergens.

In other news

• A human case of H5N1 was reported in Chile, and several new cases of infection in companion animals have been reported in North America. As I wrote last month in Foreign Affairs, I would like to see CDC update its H5N1 risk assessment to reflect the latest scientific and epidemiological developments. The risk assessment was last updated in March 2022.

• There is still very little publicly available information about the outbreaks of Marburg in Equatorial Guinea and Tanzania. The outbreaks are unrelated to one another, but both are marked by an absence of detailed updates. According to the latest available information, the outbreak in Equatorial Guinea stands at 14 cumulative confirmed cases and 10 deaths. In Tanzania, 8 cases and 5 deaths have been reported. CDC issued a Health Alert Network dispatch this week warning clinicians to be alert for patients with symptoms such as fever, headache, muscle and joint pain plus relevant travel history.
• The end of the Public Health Emergency (PHE) is about one month away. Don’t forget to stock up on at-home antigen tests. Private insurers and Medicare are required to reimburse eight tests, per covered person, per month. That requirement will end on May 11, when the PHE ends. Clinical diagnostic testing will continue to be covered, but there may be cost sharing depending on your plan.
• I answered reader questions in the New York Times again this week, this time on rebuilding trust in public health and combatting misinformation. You know, the easy stuff. Let me know what you think in the comments.