Thread by @kerpen

Friday Fluday Thread, MMWR Week 10

Please remember who told you we'd skip flu season and who screamed twindemic!

United States Influenza testing, MMWR week 10.

CDC flu view. cdc.gov/flu/weekly/ind…

Five-year average: 7,967 cases; 22.45% positive

Last year: 10,158; 22.38%

This year: 28; 0.09%

docs.google.com/spreadsheets/d…

United States Influenza testing, season to date (24 weeks, MMWR 40 to 10)

Five-year average: 166,096 cases; 18.47% positive

Last year: 262,224; 22.91%

This year: 1,822; 0.16%

Season-to-date U. S. flu hospitalizations down 98.9% vs. last year, which was a typical year.

Flu hospitalizations FluSurv-NET catchment through week 10:

Total:
Last year (23 weeks): 17,889
This year (24 weeks): 203

Rate:
Last year: 61.6 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; decline of recent weeks has ended.

Still just one U.S. pediatric flu death this season. (There are 107 pediatric deaths with COVID this season.)

CDC total estimates total pediatric flu deaths several times higher than these lab-confirmed counts. Not enough flu for estimates this year.
cdc.gov/flu/about/burd…

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.

HCoV-OC43 and especially HCoV-NL63 comebacks continue as SARS-CoV2 recedes.

syndromictrends.com/metric/panel/r…

Florida. Schools open all year. No lockdowns since September. Rhinoviruses and some adenoviruses but nearly no flu; PIV has reappeared. RSV rise has stalled around normal levels for this week.
floridahealth.gov/diseases-and-c…

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

Sweden week 10. No masks, no lockdowns, no school closures -- and nearly a full year with no Flu A, Flu B, or RSV. HCoVs have come back.
karolinska.se/globalassets/g…

Brazil. Infamously lax control measures, and a president who urges people to disregard them. Still no flu.
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.

Japan masked hard in 2019 and failed to stop a major flu outbreak. But in 2020 flu disappeared with only low stringency COVID intervention.

https://twitter.com/ianmSC/status/1365091758887997440

The idea mitigations worked but unmitigated SARS-CoV2 just has a higher R (popular now among the same crowd that said twindemic! when failed to notice 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 the last month when SARS-CoV2 declined.

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.

There was some hope flu would disrupt COVID. Looks like the opposite happened.

thelancet.com/journals/lanmi…

I share this great short article from @m_soond explaining the viral interference theory of this respiratory season every week. medium.com/illumination-c…

The bottom line is -- regardless of why we had the season we did -- we locked kids out of school during the *safest* respiratory season for children ever recorded.

The empty pulmonary wards became overflow for kids on *mental health* admissions.

That's a disgrace.