Madam Chair, thank you for the question.
We have adopted procedures to ensure that people are properly isolated and don't pick up threat vectors as they are about to embark on a mission like this. In spite of our best efforts, there was a concern that someone may have been in contact with a person with COVID-19 as they moved as a group towards the point of embarkation in the aircraft. It was then deemed appropriate for the plane to return and have proper measures put in place.