The Case for a Humidifier and Other Cutting-Edge Research on the Flu

The Case for a Humidifier and Other Cutting-Edge Research on the Flu

The Case for a Humidifier and Other Cutting-Edge Research on the Flu

Every month, we get into a different health topic and explore the research. And now, ’tis the season: We’re looking into some of the most informative new studies on flu prevention and highlighting the key takeaways.


Prebiotics and Probiotics Boost the Effectiveness of the Flu Vaccine

Nutrients (2017)

Getting a flu vaccine is the single best thing you can do to protect yourself from the flu. It prevents anywhere between 70 to 90 percent of infections, depending on the virus strain. But if you want to be extra safe this season: Consider taking a prebiotic and a probiotic. At least that’s what a 2017 meta-analysis by researchers in Taiwan concluded. They analyzed nine studies that involved a total of 623 adults. And they found that participants who took probiotics or prebiotics before receiving the H1N1, H3N2, or influenza B flu vaccination were significantly more protected against contracting the viruses than participants who only received the vaccinations. The most commonly used probiotic was Lactobacillus casei or Lactobacillus paracasei, while the most commonly used prebiotic was fructooligosaccharide mixed with different oils or vitamins and minerals.

Vaccine effectiveness is measured by seroprotection (antibody levels that are at or above a specific cutoff that should render a low probability of infection) and seroconversion (development of antibodies in blood after vaccination). In the meta-analysis, the researchers found that the odds of seroprotection for the H1N1 vaccine were 83 percent higher and the odds of seroconversion were 52 percent higher for the pre- and probiotic users. The odds of seroprotection for H3N2 were 185 percent higher and the odds of seroconversion were 154 percent higher for the pre- and probiotic users. For the influenza B vaccine, the odds of seroconversion were 111 percent higher for pre- and probiotic users, but the seroprotection rate was not significantly different between the users and nonusers.

When the researchers analyzed results by age, they found that healthy older adults had the best response to influenza vaccines after prebiotic and probiotic supplementation.


Hand Sanitizer Doesn’t Kill Germs as Well as Handwashing

mSphere (2019)

Every winter, there is a national outbreak of the flu in the US—caused primarily by human influenza virus types A and B. We do what we can to keep ourselves and others protected: Stay up to date on flu vaccinations (because: herd immunity), avoid that sniffly coworker, and keep our hands clean.

The World Health Organization currently recommends washing hands frequently or, alternatively, applying hand sanitizer for thirty seconds. But a new study from researchers in Kyoto suggests that the hand sanitizer might not be cutting it.

The researchers applied mucus samples from people with influenza A virus to the fingertips of healthy people (we hope they were compensated well for this). Then they put hand sanitizer on the participants’ fingertips. After two minutes of hand sanitizer application, the researchers found that the virus was still active on the participants’ hands. It took almost four minutes of hand sanitizer use to completely deactivate the flu virus—about eight times longer than the current flu-prevention recommendations suggest you should apply hand sanitizer.

The researchers then repeated this experiment, this time allowing the mucus to completely dry before applying the hand sanitizer (which is the method most of the previous studies on flu prevention have used). After just thirty seconds of hand sanitizer application, the virus in the dried mucus was killed. So while hand sanitizers may be effective at killing dried mucus, they aren’t so good at killing fresh, wet mucus—say, when someone covers their cough and then touches the door handle right before you or, even worse, shakes your hand. There was good news though: Washing hands with soap and water deactivated the wet virus in just thirty seconds.

TL;DR: Soap and water are the MVPs for flu season.


The Case for a Humidifier

Proceeding of the National Academy of Sciences of the United States of America (2019)

There’s a reason the flu starts to go around in the winter: Colder temperatures and lower humidity are the ideal environment for viruses to spread. But how lower humidity affects the human body has so far been unknown. So researchers at Yale decided to study the effects of humidity on mice’s ability to contract influenza A virus. To do this, they exposed mice to influenza A virus and then put them in a chamber with either 20 percent relative humidity or 50 percent relative humidity, both held at a temperature of 20 degrees Celsius.

After seven days, the mice in the 20 percent relative humidity chamber had lost weight and had a decrease in body temperature, and more of them had died compared to the mice housed in higher humidity. The researchers analyzed the mice and found that the low-humidity mice had alterations to their trachea, mucus clearance, and tissue-repair function in the airways that likely hindered their ability to fight the virus.

The authors suggest that increasing ambient air humidity can be effective for reducing flu symptoms and helping you recover when you’ve contracted the flu.


Elderberry Helps with Upper Respiratory Symptoms

Complementary Therapies in Medicine (2019)

Elderberry has long been a staple in natural remedies to ward off sickness, typically taken in the form of a sweet, deep purple syrup. And now, conventional research has begun to catch up and verify what herbalists have long known: Elderberry is helpful during cold and flu season.

A meta-analysis published in 2019 analyzed all existing studies on elderberry for upper-respiratory symptoms (which, granted, totaled only four). In these studies, the eighty-nine participants who were randomized to take elderberry at the onset of symptoms had significantly reduced upper-respiratory symptoms compared to the ninety-one control subjects who did not take elderberry. The doses of elderberry in the studies were pretty variable: Participants took four tablespoons of elderberry syrup four times per day in two of the studies; 175 milligrams of an elderberry lozenge four times a day in one study; and 300 milligrams of elderberry extract four times a day in another study.

When the researchers separated the studies by the cause of respiratory symptoms for subanalysis, they found that elderberry was most effective at reducing the duration and severity of symptoms associated with the flu, rather than a cold (although there was only one study on colds, so this subanalysis may be biased). While more randomized, controlled trials on elderberry supplementation are still needed, the current research suggests that elderberry deserves a spot in our flu-prevention arsenal.

This article is for informational purposes only. It is not, nor is it intended to be, a substitute for professional medical advice, diagnosis, or treatment and should never be relied upon for specific medical advice. To the extent that this article features the advice of physicians or medical practitioners, the views expressed are the views of the cited expert and do not necessarily represent the views of goop.