As recently announced in the Guidelines on the progressive restoration of transport services and connectivity, European Union Aviation Safety Agency (EASA) has published COVID 19 Aviation Health Safety Protocol.
The Protocol is a joint effort by EASA and European Centre for Disease Prevention and Control (ECDC), defining measures to ensure safety and health of both airline passengers and all aviation frontline staff.
The measures are divided by categories, each category representing a part of the journey, and are meant to be flexible, thus allowing tailor made solutions for each Member State, airport or airline.
COVID 19 Aviation Health Safety Protocol can be found here: https://www.easa.europa.eu/document-library/general-publications/covid-19-aviation-health-safety-protocol