The major impact of COVID-19 has been that the severity of respiratory symptoms require intensive hospital treatment. There is significant mortality and many of the survivors have a delayed recovery requiring intensive prolonged rehabilitation.

COVID-19 is a multi-systemic disease in which different mechanisms within the body are affected; including the 'Gut microbiome'. 'Gut microbiome' refers to the bacteria living in intestines. While some bacteria is harmful, many are extremely beneficial and necessary for a healthy body. Many patients have gastrointestinal symptoms and there is a major change in the gut micro flora (microbiome), which may have an adverse effect on the respiratory symptoms. The probiotic, Sivomix, was given to hospitalized COVID-19 patients was associated with a more rapid recovery in gastrointestinal symptoms on day 3 and 7, and an eight fold reduction in the requirement for mechanical ventilation in an open trial.

This is a randomized clinical trial, with a recruitment target of 60 patients admitted with COVID-19 symptoms to the general medical wards. Patients will be randomized to receive the probiotic, Symprove, or placebo in addition to their standard of care treatment. Patients will need take either probiotic/placebo daily for 3 months. All follow-up will be whilst they are an inpatient or as a telephone follow-up; they will not need to attend at the hospital to participate.

There is a biological sub-study incorporated into the protocol, but participation is optional. If patients consent to this, they will also need to provide blood, faecal and saliva samples at baseline, Day 7 and final visit (3 months after randomisation). Patients who consent to providing biological samples will need to visit the hospital at Day 7 and final visit.

Inclusion Criteria:

• Symptomatic patients who are hospitalised with respiratory COVID-19
• Ability to give informed consent
• Aged 20-85

Exclusion Criteria:

• Patients not meeting the inclusion criteria that have COVID-19
• Inability to consent
• Pregnancy
• Severe pre-existing mental health disorders or addictions