Can nasal irrigation reduce the number of hospitalisations due to covid-19?

There is an article circulating on the internet signed by a person who identifies himself as Joseph Mercola stating that "nasal irrigation may help in preventing hospitalisations for covid", and that these conclusions are drawn from "a study" which "showed that people who irrigated (washed) their noses with normal saline were 19 times less likely to be admitted to hospital for COVID-19 than the national rate". This is UNVERIFIABLE at the moment. There is not enough scientific evidence to confirm or disprove this claim.

"Nasal irrigation could help prevent hospitalisations due to COVID".

The debate on whether frequently cleaning one's nose with salt can help prevent covid-19 infections or make them less frequent is not a new one. Since the start of the pandemic, a number of opinion articles have been written in several scientific journals suggesting the need to investigate this possibility, especially in a scenario such as last year’s, when vaccines were not yet available. 

However, the study reported by Mercola has not been published in a peer-reviewed journal, that is, it has not yet passed the independent filtering process that ensures that the paper he is talking about has minimum quality standards and is reliable. Therefore, until it has passed this screening, the results it shows must be left in doubt. 

The opinion of the WHO and the FDA

The position of the World Health Organisation (WHO) is clear: "There is no evidence that washing your nose with salt has protected people from becoming infected with the new coronavirus" and "there is some very limited evidence to suggest that it may help people recover more quickly from the common cold". 

In any case, they conclude, "regular wiping of the nose does not seem to prevent respiratory infections". 

In line with these affirmations are those of the US Food and Drug Administration (FDA), which in mid-September 2021 issued a statement insisting that "there is no nasal spray that has been shown to prevent covid-19". 

The statement came after such a product was being advertised in the Philippines, claiming it could help in reducing the severity of the disease: "These sprays contain substances that coat the nasal mucous membranes with substances that do not have a specific effect against pathogens" and are not made with "active pharmaceutical ingredients that directly treat, prevent or eliminate diseases".

Lack of good scientific evidence

What pushes scientists to investigate the possible potential of nasal saline irrigation as a preventive treatment for covid-19, and to add it to the list of measures that have been empirically proven to reduce transmission of the virus, such as the well-known face masks, safe distance and hand washing. 

Moreover, experts insist that it is a cheap and easily scalable option that has already been studied in other respiratory diseases, such as chronic rhinosinusitis, where it has been observed to reduce the symptoms of this ailment.