An expert panel has written a white paper with a set of recommendations regarding the diet and micronutrient supplement needs of the Swiss and wider European population in order to support immunity during the COVID-19 pandemic.
Their recommendations (page 8 of the white paper) include:
Vitamins C and D, DHA and EPA, Selenium and Zinc.
For EPA and DHA, they suggest 500mg /day but this is wrong as we have explained here.
The strange thing is that they quote this paper of Calder et al which suggests a daily intake of EPA and DHA of 250mg/day but in their own white paper, they feel that 250mg is low and they double it to 500mg/day.