Every flu season — and especially during the dire ones, like 2017-18 — health officials shift into overdrive, imploring employers and schools to disinfect doorknobs, use no-touch trash bins, and promote extended hand washing with soap.
Problem is, this advice falls far short.
Yes, the influenza virus is spread via surfaces, but just as often, it’s spread through the air. So while sanitizing doorknobs and handrails helps, containing this relentless and often deadly virus requires cleaning the air, too.
“Breathing, talking, coughing, and sneezing release influenza virus into air,” writes Werner Bischoff, author of a study conducted at Wake Forest University School of Medicine and published in The Journal of Infectious Diseases.
That’s right — merely breathing can send enough particles of flu virus airborne to infect anyone in the vicinity.
Bischoff’s team found that medical providers within 6 feet of infected patients can be exposed to infectious doses of the virus — even if patients are breathing normally, not hacking up a lung. That’s because the particles released via exhaling and talking are so small and light they can hover in the air indefinitely and travel significant distances.
Coughing and sneezing, by contrast, release large virus particles that typically sink in short order. Up to 89 percent of flu-carrying particles are of the small, nomadic variety, Bischoff’s team notes.
So even if every flu-infected person sneezed into a tissue and covered their mouths to cough — a pretty huge “if” — the virus would still wander freely. It’s not as if you can advise people to stop breathing.
As for handwashing, 70% admit they’ve bypassed the soap in public bathrooms, and most don’t wash for the recommended 20 seconds. One-third of adults concede they don’t even reliably wash up after using the restroom.
But even total handwashing compliance wouldn’t contain the flu. The virus only lives on human hands for 15 minutes, whereas virus particles can waft through the air for hours, even days.
What’s more, airborne flu particles have 8.8 times more flu virus than surface particles, a study in PLOS Pathogens found. And some flu patients are far more contagious than others. One study found that among hospital patients who released influenza into the air, 19% emitted up to 32 times more virus than other patients. There’s no way of identifying the extreme emitters walking and breathing among us.
If every flu patient wore a surgical mask — now, that would actually make a difference, according to the PLOS authors. But that’s hardly a containment strategy to rely on, especially since you can infect others with influenza a day before you even know you’re sick.
Vaccination, of course, is the best way to prevent flu epidemics, ideally immunizing folks from both surface and airborne virus particles. But even in a good year, vaccines only reduce the risk of contracting the flu by 40% to 60%, and they work better on certain strains of influenza than others. More than 30 strains of influenza A and B have been identified, and each year brings a new round of educated guessing, as the virus mutates rapidly.
“The virus has evolved to be a cunning vaccine-avoiding machine,” as one virus expert put it.
What can be done?
A large body of scientific literature has emerged in recent years confirming that airborne spread of influenza is a significant threat — and that ignoring this mode of transmission is risky business.
As the Wake Forest authors noted, “Millions have lost their lives to influenza in pandemics, and epidemics of varying severity occur worldwide each year.”
The flu afflicts tens of millions annually and kills up to 650,000, according to estimates by the United States Centers for Disease Control and Prevention (CDC) and World Health Organization (WHO). And that’s in an average year.
“Another pandemic is inevitable, and it will most likely be influenza,” a WHO spokesman recently told the Express. “The only known pathogen that will cause a pandemic with certainty is influenza.”
The burden on the U.S. healthcare system is so great that that the CDC tracks influenza severity with a weekly surveillance report. In the United States alone, the flu causes employees to miss 17 million workdays, at a cost to employers of $7 billion a year. Each year brings tragic stories of young, healthy people stricken by the virus and hospitals overflowing with patients in the hallways.
As one emergency-room doctor put it in 2018, “I do not think that we can overhype this right now. I do not think there is a level of caution that I would consider too extreme.”
A crisis as dire and predictable as the flu requires all hands on deck and all prevention and containment strategies deployed. Vaccination, handwashing, and surface cleaning won’t suffice; it’s time to get serious, too, about cleaning our indoor air.
Interested in learning more about the flu? Join us for a free webinar presented by Dr. Werner Bischoff, Associate Professor of Infectious Disease at Wake Forest School of Medicine.