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Avoiding COVID in 2025

·6 mins

Sometimes it seems like we’re the only people still taking precautions to avoid COVID-19. We’re not; there’s a non-zero number of other people still masking, at least here in Minnesota. It’s clear, though, that for 99% of the population the approach to take is to pretend it’s over. If you’re one of those people, you can stop reading this post.

About a year ago we heard about a possible way to reduce the chances of coronavirus infection, including SARS-CoV-2. It’s cheap, safe, has no significant side effects, and can be combined with masking for increased protection.

This is where I insert the disclaimer that I am not a doctor of any kind.

This possible defense against coronaviruses is iota carrageenan. It’s a natural substance derived from algae or moss, used as a food supplement for its ability to thicken liquids, stabilize foams and create gels. Popular with molecular gastronomy enthusiasts, or so I’ve read.

In 2021, there were some scientific studies published suggesting that a solution of iota carrageenan in saline, used as a nasal spray, might help prevent infection by SARS-CoV-2, the virus that causes the disease COVID-19. By 2023, more studies had been carried out, and the evidence was starting to look pretty good by the time we learned about it.

Still, after the ivermectin debacle I was wary of reading too much into a small number of early research papers. I wrote a draft of this post, but decided against posting it online. We did quietly start using iota carrageenan nasal spray, though; we figured the risks seemed minimal, and it might work, so why not?

If that sounds like the sort of thing people said about hydroxychloroquine, ivermectin, household bleach and antibiotics as COVID cures, well, this is different, because iota carrageenan has a plausible method by which it might work. Horse dewormer, antibiotics and anti-malarial drugs have no mechanism by which they might be expected to fight off a virus. But the SARS-CoV-2 virus is known to infect people via the epithelial cells of the nasal cavity. Spraying the nasal cavity with iota carrageenan results in a gel-like film on the inside of the nose. This apparently affects the virus’s ability to bind to and infect the nasal cells.

Earlier this week I was listening to previous episodes of the BBC podcast Sliced Bread, and in an episode about cold defence nasal sprays they talked to Professor Ron Eccles, an Emeritus Professor and expert in common cold infection mechanisms. He said that yes, carrageenan sprays could help protect against the common cold and other coronaviruses by forming a protective barrier. He mentioned that he uses them himself when he might be exposed to airborne viral infection. That encouraged me to dust off this post, finish it off, and publish it.

Scientific papers #

I went back to PubMed and searched again, and found some more research papers in the last year. Here’s a selection from the full list I’ve found to date:

Because it seems to work by physically preventing infection, carrageenan also seems to be at least partially effective after exposure to the virus:

A total of 394 individuals were randomly assigned to receive I-C or placebo. Both treatment groups had similar baseline characteristics. The incidence of COVID-19 differs significantly between subjects receiving the nasal spray with I-C (2 of 196 [1.0%]) and those receiving placebo (10 of 198 [5.0%]). Relative risk reduction: 79.8% (95% CI 5.3 to 95.4; p=0.03). Absolute risk reduction: 4% (95% CI 0.6 to 7.4).

That’s just one study, but reducing risk from 5% to 1% seems pretty good to me if further research confirms it. Presumably prophylactic use is even more effective.

As an added bonus, it seems to help prevent winter colds, which are also generally caused by a coronavirus:

There are a couple more studies I found from scientists who admit financial links to a company that sells over-the-counter products containing iota carrageenan. That makes me more doubtful of those studies, but here are the links for completeness:

Caveats #

There are a few things to be aware of about iota carrageenan.

If you do get COVID, a carrageenan nasal spray might give you a false negative on your COVID test:

So isolate if you have the symptoms, even if you get a negative result.

This study suggests that a particular species of red seaweed might be required:

Also, iota carrageenan can cause inflammation of the gastrointestinal tract. Still, it’s found in ice cream, yogurt, canned meat, jams and jellies, baby milk formula, mayonnaise, soup… People are ingesting 100-250mg of it every day. I doubt the tiny amount you get from a nasal spray is going to cause inflammation. I guess if it irritates your nose, stop using it.

Is this news to you? #

I hadn’t heard about any of this. I checked various web sites that have information about COVID-19 precautions — CDC, Yale Medicine, WebMD, Mayo Clinic, healthline, WHO, NHS. No mentions I could find. Why not?

The obvious problem is that it’s hard to imagine anyone making a ton of money off of iota carrageenan nasal spray. Pfizer is selling a 5-day course of Paxlovid for $1390 retail; the negotiated government price was $529. I found an online store selling a quarter kilo of iota carrageenan for $71, so in the quantities needed for nasal spray it must cost basically nothing. So pharmaceutical companies aren’t going to be spending money researching it or publicizing it.

But beyond all that, it seems like almost everyone has lost interest in trying to avoid COVID-19. Articles about the dangers of long COVID don’t seem to make a difference. People won’t wear masks, they probably wouldn’t use a nasal spray either, so why bother to mention it?

If you’ve read this far, you’re probably one of the few still interested in not getting sick. In which case you might like to consider iota carrageenan in saline solution as a nasal spray. Ideally use it before exposure, but if you forget then it’s probably worth using it afterward. It’s not a cure for the virus, but it might help trap the virus before it manages to fully infect you.

I’m still not a doctor, and the above is not medical advice.