When a study has yet to be peer reviewed, you should take it with a proverbial grain of salt. But if new research out of U Mass proves to be correct, it offers another nice reminder of how the mouth is a window to the body.

Our earlier post about COVID severity and oral health noted how researchers had found that roughly half of COVID-related deaths didn’t seem to be related to the usual risk factors – age, obesity, high blood pressure, and so on. Might there be better biomarkers, ones that could more accurately predict COVID severity?

Yes, says the new U Mass study.

It is known that a viral infection of the lung has a long-term impact on the gut microbiome. The researchers, therefore, made use of this knowledge to predict the severity of COVID-19, relating it to other common measures. They tested the effect of using clinical variables only, intestinal microbiome composition only, oral microbiome composition only, the first two combined, and the first and third in combination.

Using “the largest COVID-19 patient cohort reported for microbiome studies,” the team found that bacteria in the mouth were about 10% more accurate than the usual biomarkers. Tests of bacteria in the gut were even more accurate. Overall, they were predictive more than 90% of the time.

This is a 122% and 111% improvement in accuracy, respectively.

When both microbiomes were considered together, accuracy jumped to 96%, “suggesting that the oral or gut microbiota are better at predicting COVID-19 severity.” Perhaps this isn’t surprising considering that oral and gut health are connected.

These findings come on the heels of related research on gut health and COVID, such as a recent study in the journal Gut which likewise found a relationship between dysbiosis (bacterial imbalance) and COVID severity.

Associations between gut microbiota composition, levels of cytokines and inflammatory markers in patients with COVID-19 suggest that the gut microbiome is involved in the magnitude of COVID-19 severity possibly via modulating host immune responses. Furthermore, the gut microbiota dysbiosis after disease resolution could contribute to persistent symptoms….

The U Mass study took the further step of identifying which bacteria seemed to be most predictive of COVID severity. In the gut, it was Bacteroides uniformis, Enterococcus faecalis, and Monoglobus pectinilyticus; in the mouth, Porphyromonas endodontalis, Veillonella tobetsuensis, and Bifidobacterium breve.

The best single predictors of severe COVID? E. faecalis, found in the gut, and P. endodontalis, found in the mouth. That bacterium, by the way, is associated with periodontitis, endodontic infections, gingivitis and tooth pulp necrosis, and is found mostly in symptomatic infections but may be found in asymptomatic infections, as well.

Yet another reminder to keep up your home hygiene and regular dental visits. A healthy mouth is required for a healthy body, after all.