For policies issued after 6 November 2020 Snowcard provides cover for certain claims for Covid-19 as detailed on https://www.snowcard.co.uk/content/coronavirus-covid-19-information
If you have a European Single Trip Policy and you are travelling against FCDO advice you will be covered for certain Covid19 risks as detailed on the above link. For worldwide travel and for annual multi trip policies, cover for Covid19 is only provided if you are travelling to a country the FCDO are advising it is safe to visit.