Flu Season Update

[willrod1989]

Hello, everyone. I hope you are all enjoying the New Year. I wanted to give you all an update about this year's flu season.

We are currently seeing a surge here in Southeast Michigan that is being driven by the new Subclade K of H3N2 influenza. I have been tracking several outbreaks in Metro Detroit and local public health authorities closed some schools early prior to the Christmas holiday break. Not surprisingly, flu is currently surging in over half of the United States, with the Rt ranging between 1.3 and 1.8 in states that are currently seeing this variant. The Rt value is similar to the basic reproduction number (R0) but is a dynamic "snapshot" of how many people get infected on average at any given time. To put things in perspective, most average flu seasons see an Rt close to 1. Additionally, at the national level, test positivity rates are around 25%. Anything above 10% is considered an epidemic. These numbers are similar to what was experienced at this point during the 2003-2004 flu season, which was the most severe on record in the 21st century. Anecdotally, I'm hearing of more severe infections in adults with more mild infections in children.

This year's influenza vaccine has a moderately weaker reaction against this year's strain but continues to provide excellent protection against severe disease. If you have not yet been vaccinated, it is never too late to do so. I would also recommend wearing a high-quality mask (preferably an N-95 or similar) in public spaces, at least for the time being. I will continue to monitor the situation and provide updates when appropriate.

 

[DEFCON Warning System]

I was just about to ask how effective this year's flu vaccine was against this year's flu variant.

 

[willrod1989]

It's not a good match against infection or symptomatic illness but appears to reduce the risk of severe illness by around 80%. The problem this year is the infectiousness of this particular strain. It's best to combine vaccination with non-pharmaceutical interventions such as masking and hand hygiene.

 

[Deleted account]

Our collective approach to influenza is actually a good example of how humans are terrible at judging risks. More specifically, we tend to fear things that, statistically speaking, pose minimal threat (such as terrorist attacks), and - conversely - don't fear things that are, in fact, really dangerous (such as nuclear proliferation).

As for flu, people shrug when they hear about it - when in fact it's a serious illness that can absolutely kill you if you happen to be in an at-risk demographic. Mental exercise: imagine a world where there's no flu - until, one day, a flu pandemic (of the sort that sweeps the world every year) breaks out. We'd literally be talking about nothing else and taking extreme measures to protect ourselves.

My humble recommendation is that we all reflect on our cognitive biases from time to time.

 

[willrod1989]

Our collective approach to influenza is actually a good example of how humans are terrible at judging risks. More specifically, we tend to fear things that, statistically speaking, pose minimal threat (such as terrorist attacks), and - conversely - don't fear things that are, in fact, really dangerous (such as nuclear proliferation).

As for flu, people shrug when they hear about it - when in fact it's a serious illness that can absolutely kill you if you happen to be in an at-risk demographic. Mental exercise: imagine a world where there's no flu - until, one day, a flu pandemic (of the sort that sweeps the world every year) breaks out. We'd literally be talking about nothing else and taking extreme measures to protect ourselves.

My humble recommendation is that we all reflect on our cognitive biases from time to time.

I definitely agree. The reason that I am so concerned about this season is how it behaved in Australia. They saw a record-breaking flu season in terms of laboratory-confirmed cases, and it's extrapolated to be similar to the 2003-2004 flu season, which was the worst flu season since the 1968 Hong Kong flu pandemic. If we were to look at how the 2003-2004 flu season behaved (which is likely a close analog to this developing flu season), one could easily make the argument that it was similar to a Category 2 pandemic on the Pandemic Severity Index.