Thread by @kerpen

Friday Fluday Thread, MMWR Week 9

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

United States Influenza testing, MMWR week 9.

CDC flu view. cdc.gov/flu/weekly/ind…

Five-year average: 8,271 cases; 23.16% positive

Last year: 11,782; 25.57%

This year: 22; 0.08%

docs.google.com/spreadsheets/d…

United States Influenza testing, season to date (23 weeks, MMWR 40 to 9)

Five-year average: 152,516 cases; 17.88% positive

Last year: 245,227; 22.71%

This year: 1,764; 0.17%

Season-to-date U. S. flu hospitalizations down 98.8% from last year, which was a typical year.

Flu hospitalizations total (23 weeks) in FluSurv-NET catchment is 200. Through week 9 last year (22 weeks) it was 16,819.

Rate last year: 57.9 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, and is declining when it was rising in those years.

Still just one U.S. pediatric flu death this season. (There are 99 pediatric deaths with COVID this season.)

Influenza-Like Illness (ILI) Map

Week 9: 2021, 2020, 2019, 2018

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

Lots of rhinoviruses and some adenoviruses all year.

HCoV-OC43 and HCoV-NL63 comeback continues as SARS-CoV2 recedes.

Flu A and RSV reappear.

syndromictrends.com/metric/panel/r…

Florida. Schools open all year. No lockdowns since September. Rhinoviruses and some adenoviruses but nearly no flu. RSV returned in recent weeks and is rising toward normal levels.
floridahealth.gov/diseases-and-c…

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

Sweden week 9. 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.

But flu is not gone everywhere.
apps.who.int/flumart/Defaul…

I don't think it's masks, which have 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 low stringency COVID intervention.

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

The idea mitigations worked but unmitigated SARS-CoV2 just has a higher R is way too facile.

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 few weeks 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.

thelancet.com/journals/lanmi…

And H1N1 dominated other flu viruses that year -- a skipped seasonal flu season. No masks, lockdowns, or distancing needed.

https://twitter.com/Humble_Analysis/status/1365035607248969728

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. Shameful.

This short article from @m_soond is still the best theory in my opinion.
medium.com/illumination-c…