Thread by @PeterKolchinsky

I’m a virologist & #1 question I got today was whether to gargle & with what. If SARS2 seems to infect throat before spreading to lungs, might gargling protect people from infection? (Thank you to my colleague @jrpritz for research!) Turns out, people have run studies and…

…results are mixed. Bottom line: it probably doesn’t work, but if it does, then water is enough, and it won’t hurt to try it IF YOU DON’T GARGLE WITH POISON. It’s important to know that gargling to kill & wash away bacteria isn’t the same as trying…

…to kill viruses, because viruses get inside of your cells. It would be like spraying high pressure water to remove a sticker on your arm vs a tattoo. You can remove a tattoo that way, but only by removing your skin. Most bacteria are like stickers that stay outside of cells…

…(though some do sneak inside cells, like viruses). But viruses must get into cells to hijack their machinery to make copies of themselves. So, theory is gargling might wash away or kill viruses on outside of your throat cells in hopes of keeping them from infecting cells.

Once they get in, which they can do quickly, hard to see what gargling could do. That means that if gargling were to work, you would have to do it frequently (probably more so when around others, which ordinarily is often but these days hopefully less so).

So does gargling work? Some people definitely think so. Japan widely believes gargling water multiple times a day can prevent upper respiratory tract infections & it is included as basic preventive measure for respiratory infection such as COVID-19…

...alongside hand-washing and mask-wearing. But is this based on data from proper clinical trials that compare infections for people who gargled vs didn’t? A Japanese group ran a trial in 387 volunteer & found gargling water 3-4 times a day…

...reduced the chance of getting an upper respiratory tract infection by 36% but gargling with Betadine (povidone-iodine) did not have any benefit. ncbi.nlm.nih.gov/pubmed/16242593

You might think, “great, so water works!”. Maybe, but we’ll get to that. Note that Betadine didn’t work, though it’s mostly water and the chemicals in it have been shown to inactivate virus, so you would think it should have been better.

But the researchers point out that Betadine also can damage cells, so maybe that counteracts the benefits of water, possibly making it easier for virus to infect. That’s just speculation. But gargling with Betadine certainly doesn’t look better than water.

But before we concluded that gargling with water worked, we looked for another trial to confirm that result. The only other controlled trial we found was large Canadian one (600 people) that saw no effect of gargling with water.

There were actually slightly more infections in those who gargled, but the difference was not statistically significant, so probably just a chance fluctuation in the data.
ncbi.nlm.nih.gov/pmc/articles/P…

We couldn’t find more controlled studies comparing gargling to no gargling to prevent upper respiratory tract infections. Maybe there are some out there, in which case please send them to me.

Some studies just have people gargle without comparing what happens to them to people who don’t gargle. This is called an “uncontrolled” trial. And you can’t really interpret the results of such trials, because...

...our chances of catching an infection vary from season to season, by different age groups, and by region (more in cities since more crowding). So what seems like a lower rate of infection in an uncontrolled study compared to what you see on average…

…might just be due to testing gargling in people who don’t have kids and so don’t deal with them bringing infections home from school, or maybe that year there were fewer colds or strep going around.

You need a control group of people and few studies bothered to include one. That’s not great science. Besides clinical studies, there are lab experiment. Eg, a German study showed Betadine (povidone-iodine) inactivated SARS & MERS in a test tube.

But we already know that didn’t turn out so well in a clinical study. Hydrogen peroxide and ordinary mouthwash (e.g. listerine) has been shown to inactivate coronaviruses & flu because it’s actually easy to disrupt their greasy outer coats (lipid membranes).

But there are no compelling clinical data that these work, and even if you believe the Japanese study showed water works, then there’s no evidence that other gargling solutions (dilute hydrogen peroxide, mouthwash, etc) are better than water.

Some think gargling should work by washing away dust mites that make protein-clipping enzymes that maybe activate viruses, letting them enter cells (kind of like cutting a tight rubber band makes it spring into action).
jstage.jst.go.jp/article/intern…

To be clear, dust mites do not make enzymes in order to activate viruses. They make enzymes that do things for themselves and that happen to resemble enzymes that our own cells make that viruses evolved to hijack for their own schemes.

Viruses are like MacGyver (American reference)… using what they find to survive and thrive. In any case, the dust mite hypothesis is just a wild guess. What matters are clinical data, and those don’t speak to whether dust mites are relevant.

So bottom line is there’s reason to think that one could inactivate or wash away viruses from the surface of one’s throat before the viruses could infect the cells, but whenever we’ve looked for evidence that this actually works, the evidence is, at best, weak.

Nevertheless, given the low cost & risk of harm from gargling with water, salt water, mouthwash, dilute hydrogen peroxide (1%), or (if one really must) even dilute betadine (1%), do it if it makes you feel better.

If you choose to gargle, here are some safe solutions: tap water, salt water (1/4-1/2 tsp salt in 8oz of water); 1% hydrogen peroxide (1 part 3% hydrogen peroxide, 2 parts water); 1% betadine (povidone-iodine). Note: never swallow a gargling solution.

ABSOLUTELY don’t use high concentrations of hydrogen peroxide! Pharmacies sell 3%. Food-grade stuff (35%) is not food! It can scorch your tissues, mix with stomach acid & make you foam from your mouth. Warning video: nowthisnews.com/videos/food/dr…

And finally, safe gargling (even if it did have some benefits) isn’t a substitute for everything else you need to do to stay healthy during this pandemic. It’s just an add-on to social distancing, hand washing, and, if you have to go out, masks.

This isn't the kind of research I thought we would be doing today, but it was somewhat interesting. In our search for new, often complex drugs, we sometime don't explore fully the simple solutions. Glad to see some researchers out there have. Probably merits one more study.

If you found this explanation easy to understand, I've tackled other aspects of COVID19 in other threads and in three articles on @CityJournal that many people have said they found easy to follow city-journal.org/contributor/pe…

And shortly before COVID19 took over our lives, I published a book that speaks plainly about our healthcare system, insurance, and drug affordability. When we misunderstand the root causes of a problem, we can't focus on the right solutions. check it out. thegreatamericandrugdeal.com