COVID-19 patients have an increased risk of contracting bacterial co-infections. Triggers of this may include oral bacteria that accumulate in the oral cavity. They can spread from there to other areas of the body and cause infections. Older people are particularly vulnerable. In order to guard against this, it is important to practice thorough oral hygiene.
Viral respiratory tract infections make patients more susceptible to bacterial co-infections.  The co-infections in turn lead to increased disease severity and mortality. A Chinese study demonstrates that during the coronavirus pandemic, 50% of deceased COVID-19 patients had concurrent, secondary bacterial infections.  Another Chinese study identified both bacterial and fungal co-infections. 
Oral bacteria as triggers of co-infections
The development of co-infections in COVID-19 patients is promoted by oral bacteria that spread throughout the body. Analyses of genomic material from patients with SARS-CoV-2 showed high values of cariogenic and periodontal pathogenic bacteria. This confirms the view that there is a link between the oral microbiome and COVID-19 complications. 
In addition, there is evidence that periodontal pathogenic bacteria are involved in the onset and development of respiratory diseases associated with COVID 19. Moreover, these bacteria are associated with chronic-inflammatory systemic diseases including type 2 diabetes, hypertension and cardiovascular diseases. These diseases are therefore often comorbidities, which increase the risk of severe complications and death in cases of COVID-19. 
Oral hygiene is particularly important for the elderly
In contrast, other studies demonstrate that the clinical outcomes considerably improve and the mortality decreases for patients suffering from pneumonia when they implement improved oral hygiene.  One in ten pneumonia-related deaths among elderly care home residents aged 65 years and older are deemed avoidable thanks to improved oral hygiene. 
Conclusion: These connections illustrate just how important thorough oral hygiene is for infection prevention. Good oral hygiene is particularly vital for older patients and residents in nursing facilities in order to reduce the germs in the oral cavity and to prevent the spread of oral bacteria to other parts of the body.
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