I recall many years ago when DVT hit the news big time the advice to people taking long haul flights was to wear compression socks, get up and walk around to get the blood flowing and (as goldfish first stated) take an asprin as you board the plane.
When I got the 1st AZ shot last month my doctor told me to watch for symptoms (numbness, severe headaches) around day 3 as evidence showed this was the time it took to develop.
What I can't understand and has goldfish has been tryin to explain is why don't they tell people "GET THE AZ SHOT AND POP AN ASPRIN ON DAYS 1 AND 2"