Participants were required to take 2 mL of early harvest olive oil (normal early harvest olive oil) twice a day for three months and went through a clinical questionnaire at days 15, 30, 60 and 90. Participants were sent an envelope closed with instructions and informed consent. The primary outcome was to determine the effect of high polyphenolic olive oil on Coronavirus disease incidence, duration and severity. This study was approved by the independent ethic committee of the Hospital Nuestra Señora del Prado in Talavera de la Reina, belonging to the National Health System in Spain, and conducted in accordance with Declaration of Helsinki and Good Clinical Practice guidelines. Written informed consent was obtained from all patients. This questionnaire consisted in asking about having symptoms of SARS-CoV-2 infection, fever, low fever, malaise, headache, loss of smell, runny nose, sore throat.

Participants were required to complete a questionnaire at days 15, 30, 60 and 90 of the study. This questionnaire consisted in asking about having symptoms of SARS-CoV-2 infection, fever, low fever, malaise, headache, loss of smell, runny nose, sore throat.

High polyphenolic olive oil is normal olive oil obtained from early harvest olives, this early harvest olive oil has been widely used for culinary purposes for centuries. The investigators wanted to study if oromucosal immunoprophylaxis with small quantities of high polyphenolic olive oil (2 mL of olive oil equivalent to 5 mg of polyphenols) adiministered twice a day could have clinical mitigating effects on the disease caused by SARS-CoV-2 infection.The primary outcome was to determine the effect of high polyphenolic olive oil on Coronavirus disease incidence, duration and severity.

High polyphenolic olive oil immunoprophylaxis intervention and incidence of COVID-19.

Time to resolution of symptoms of COVID-19 in participants versus normal population.

Differences in severity of symptoms of COVID-19 between participants and control group.