Is it “worth giving a try”?
Among the dozens of corona medicines that have been “advertised” recently as coronavirus treatment or effective in the diagnosis of covid-19, there is one that, at least in theory, has some scientific basis.
Social media is flooded with adverts for bogus COVID treatments. There was hydroxychloroquine first, followed by bleach, and then ivermectin – a cattle dewormer. The most recent addition is povidone-iodine, an antiseptic.
Some such people have claimed on social media that gargling with iodine can help prevent the spread and severity of a COVID infection, suggesting that it could be used in lieu of the vaccine.
For nearly two centuries, iodine has been used as an antiseptic, with povidone-iodine being a widely used modern preparation. It has been shown in laboratory studies to be effective against coronavirus, blocking it in as little as 15 seconds.
This led the researchers who made the discovery to propose that using povidone-iodine in the nose and mouth could significantly lower coronavirus transmission and severity of infection in those infected. This is based on the assumption that what occurs in the test tube will occur in humans, which is a significant leap of faith.
The concept of preventing infection in the mouth has existed for some time. Until the 1970s, the makers of Listerine mouthwash claimed that regular use of the product could help prevent colds and sore throats, but were forced to withdraw this claim due to a lack of evidence. Since then, trials examining the efficacy of gargling to prevent colds and flu have produced inconsistent results, with little evidence of any worthwhile benefit.
Gargling daily for hygienic reasons has been a widespread cultural discipline in Japan for centuries, involving everything from water to tea to antiseptics. In an August 2020 press conference, the state governor of Osaka prefecture suggested that gargling with povidone-iodine could help prevent COVID. When pressed on the strength of the scientific evidence, he averted the question, responding: “It’s worth giving a try.”
Similarly, oral-health experts in the United Kingdom have offered similar advice based on a hunch.
A recent review of studies sought to address the following question: Does povidone-iodine reduce COVID spread? The majority of this research was conducted in laboratories, with only a few trials conducted on humans.
While these patient-based studies indicate that povidone-iodine can temporarily inactivate coronavirus in the mouth – an unsurprising finding – there is no evidence to date that it can prevent coronavirus transmission or reduce the severity of disease in those who are already infected.
The “worth giving a try” argument is dubious. From a practical standpoint, many patients find it difficult to use povidone-iodine in the mouth and nose due to its taste and odour. While the majority of povidone-side iodine’s effects are tolerable, skin irritation is common and can be severe. Povidone-iodine can occasionally, but more seriously, cause an underactive thyroid gland, particularly in pregnant women.
The manufacturers of povidone-iodine are explicit in their warning that their products are not intended for gargling or inhalation to prevent COVID.
Apart from the immediate risks associated with the use of povidone-iodine inside the body, there is a negative effect associated with promoting pandemic treatments that are not based on reliable evidence, particularly when there are measurably effective alternatives. While gargling with iodine will not prevent you from contracting COVID, it may divert your attention away from something that will: vaccines.
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