Why so little flu this winter?

Translating science into effective action has always been a complicated business. For technology transfer, it took two centuries before Newtonian physics spread to engineering safer bridges and buildings. It took two generations to ban smoking in crowded places. But occasionally there are dramatic results that ought to create respect for expertise.

Last spring, we worried about a double hit on hospitals when the flu season arrived in the midst of the Covid-19 pandemic, a “twindemic.” There was, of course, a chance that pandemic precautions would also reduce the flu load — indeed, Covid precautions seemed to cut short the 2019–20 flu season by six weeks (dark green line in March). It certainly wasn’t something to rely upon in our planning. Mentioning it might have given President Trump another excuse to minimize government action.

US flu seasons since 2015–16. The red line is the current 2020–21. Source: Sciencemag.org

Now, halfway through the 2020–21 flu season (red line at bottom of both figures), there is data and it is far more impressive than I could imagine last spring. Flu has not vanished but the numbers are tiny when compared to the previous four flu seasons.

Numbers are just subtotals from a traditional group of monitoring stations around the world; total numbers would be far higher. Clipped from WSJ.

Before supporters can claim that Trump accomplished this, let me point out that it is a worldwide effect, not just the US (second figure).

Here we see the power of precautions like masks and handwashing for preventing the spread of other viruses. But there are other possible dampening factors in play for Covid that may have kept flu from spreading this year. Let me list the ones that occur to me:

  1. Reduced travel which involves many hours in compartments packed with people. There were few big conferences where people from around the world sat packed shoulder to shoulder for hours, and then flew back home.
  2. Ditto for conference room packing and going to the movies.
  3. Reduced clustering for schoolchildren as well as office workers (at least in the US; many other countries controlled spread so effectively that it was frequently business as usual, giving America’s trade competitors a big opportunity). One would have thought that business’s talking heads would have spoken about this all year, even before Trump became a loser.
  4. Reduced handshaking, hugging, and social kissing — as well as less shouting into someone’s ear, commonplace at noisy restaurants and loud parties. There are workplace regulations regarding noise levels for employees, but few for diner protection. The danger here is not so much from spread via touching doorknobs or via inhaling aerosols but from the third route that I talked about in the first of this pandemic series, spread via one invisible droplet packed with enough virus particles to start an infection all by itself. They are heavy enough to quickly fall to the floor or table, unlike the aerosols that hover. But in loud speech, a lot of such microdroplets will end up on the listener’s face, not far from nose and eyes, where a rub might deposit them.

The experts will get an opportunity to sort this out as we continue masks and handwashing but with some regions going back to international travel or normal packing density for parties, auditoriums, workplaces, and mass transit. Soon we ought to have some indicators of what are the most important actions for stopping flu and Covid-19 spread. We ought to be better able to judge “bang for the buck” issues.

There’s nothing like having a really dramatic example for what can stop flu spread; textbooks will celebrate it. But will it become easier to get the public to follow expert advice next time?

Perhaps in some countries, but recall that nearly half of Americans still voted to re-elect the President who ignored and belittled the experts for many months. Many of those same Americans, including a surprising number of governors, refused to wear a mask that protects others and even adopted this as a badge of tribal identity. They were not shunned, shamed, quarantined, or treated as aggressors as they would have been in many other countries. Reminding them that they were endangering their own relatives had little effect; they seemed to have blinders on, restricting them to the mindset served up on FOX.

Pandemic pushback shows us how big our problem is with getting the US to take quick action on climate, as there has been a strong overlap between Trump fans and climate denial. So, half of Americans may continue to be a hard sell, whatever the facts, giving other countries an excuse for shunning all Americans — provided that Trump’s Mob attacking Congress hasn’t done that already.

I am beginning to wonder if my efforts to promote a Manhattan Project for Climate ought to be directed at Europeans and Asians instead. Foot-dragging Americans are not a lost cause but time is of the essence when it comes to climate action. The time frame for effective climate action — the kind that can prevent the collapse of civilization — is the next decade, not the end of the century. And all we can seem to talk about are emission reductions that will be too little, too late. What it now takes is a CO2 cleanup that is big, quick, and sure to work (no time for a second try).

 by the author.



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William H. Calvin

William H. Calvin


President, CO2Foundation.org. Professor emeritus, University of Washington School of Medicine in Seattle. Author, many books on brains, human evolution, climate