Thread by @kerpen

Friday Fluday Thread: MMWR Week 13, ending April 3, 2021

United States Influenza testing, MMWR week 13.

CDC flu view. cdc.gov/flu/weekly/ind…

Five-year average: 3,853 cases; 15.33% positive

Last year: 708; 2.24%

This year: 20; 0.07%

docs.google.com/spreadsheets/d…

United States Influenza testing, season to date (27 weeks, MMWR 40 to 13)

Five-year average: 192,308 cases; 18.87% positive

Last year: 290,043; 21.47%

This year: 1,935; 0.15%

Season-to-date U. S. flu hospitalizations down 98.9% from last year.

Flu hospitalizations total (26 weeks) in FluSurv-NET catchment is 215 (+2 from last week). Through week 12 last year (25 weeks) it was 19,713.

Rate last year: 67.9 per 100K
This year: 0.7 per 100K

Influenza-Like Illness (ILI) continues to track well lower than the mild 2015-16 and 2011-12 seasons. Ticked up this week (HCoVs?).

Still just one U.S. pediatric flu death this season. (There are 132 pediatric deaths with COVID on the death certificates this season.)

Note that while the lab-confirmed pediatric flu death counts are 3-4x lower than CDC best estimates, the pediatric COVID death certificate total is likely overbroad.

https://twitter.com/andrewbostom/status/1379861668847566849

Latest U.S. non-SARS-CoV2 syndromic data from BioFire.

Lots of rhinoviruses and some adenoviruses all year.

Flu A, B, RSV, and PIV are all back at low levels.

syndromictrends.com/metric/panel/r…

Out-of-season HCoV surge continues after a year of absence as SARS-CoV2 recedes. HCoV-NL63 potentially post-peak HCoV-OC43 rise accelerating. HCoV-229E rising now too.

CDC surveillance confirms HCoV surge and potential HCoV-NL63 peak.
cdc.gov/surveillance/n…

HCoV-NL63 outbreak in Midwest (IA, IL, IN, KS, MI, MN, MO, ND, NE, OH, SD, WI) region. Peaked?
cdc.gov/surveillance/n…

Florida. Schools open all year. No lockdowns since September. Rhinoviruses and some adenoviruses but nearly no flu; PIV has reappeared. Rhino and PIV rose this week. RSV above baseline and rising but at a decelerating rate.
floridahealth.gov/diseases-and-c…

Sweden week 13. No masks, no lockdowns, no school closures under age 16 -- and a full year with no Flu A, Flu B, or RSV. HCoVs continue to rise.

karolinska.se/globalassets/g…

Germany week 13. Rhinoviruses and resurgent HCoVs continue to climb rapidly during lockdown. Still no flu. PIV is back.
influenza.rki.de/Wochenberichte…

Brazil. Very lax control measures, and a president who urges people to disregard them. A completely skipped flu season.
apps.who.int/flumart/Defaul…

The global flu chart from WHO.
apps.who.int/flumart/Defaul…

But flu did not disappear everywhere.
apps.who.int/flumart/Defaul…

It wasn't masks, which were never used in many countries where flu disappeared and have also been shown to be ineffective for stopping influenza in many, many studies.

apps.who.int/iris/bitstream…

Japan masks every year, and pushed masks hard in 2019 with no apparent effect. But in 2020-21 flu disappeared with low stringency COVID intervention.
apps.who.int/flumart/Defaul…

The idea mitigations worked but unmitigated SARS-CoV2 just has a higher R (popular now among the same crowd that said "twindemic!" when flu had been gone for months) is way too facile.

Outside of testing ramp up, I don't think we've seen R > 2, even in places without NPIs.

Rhinoviruses bounced right back despite lower R and RSV was gone until recently with comparable R to SARS-CoV2.

HCoVs were gone until SARS-CoV2 declined, then returned even with lockdown.

Plus, as Biden adviser Dr. Michael Osterholm points out, our mitigation just hasn't been very effective.

Maybe in places like Australia and New Zealand where mitigations stopped SARS-CoV2 they also stopped other viruses.

But in countries where SARS-CoV2 went wild? No.

Osterholm: "There is this viral interference"

Viral interference is a well-known (but poorly understood) phenomenon. Interference from rhinovirus is generally thought to have ended the swine flu epidemic in 2009.
thelancet.com/journals/lanmi…

This great short article from @m_soond explains the viral interference theory of this respiratory season:
medium.com/illumination-c…

Overall the season has been so mild that drug store chains took big losses.

Rite Aid CEO Heyward Donigan: "During the fourth quarter our industry was impacted by a historically soft cough, cold and flu season."

forbes.com/sites/brucejap…

Pediatric internships and residencies have to be extended because they just didn't have enough patients to gain the normal amount of clinical experience.

https://twitter.com/DrKristenW/status/1374095951170830336

We're seeing reports like this from all over the country. The empty pediatric wards usually used for respiratory disease have been converted to deal with the overflow child psychiatric admissions from lockdowns/school closures.

https://twitter.com/DrKristenW/status/1374911931681796098

We are now near the end of the *safest* respiratory season for children ever recorded. (And yes, that includes places where schools never closed.)

Yet many places locked children out of school, and some places are still doing so. It's a disgrace.