Bingo!
FYI...received this, in a United Airlines email....
...
In the air
Our aircraft are equipped with state-of-the-art circulation systems, similar to those found in hospitals, which use a high-efficiency (HEPA) filter to circulate the air and remove more than 99% of airborne particles. We’re also adjusting our inflight service to limit person-to-person contamination. This includes handing beverages directly to customers instead of allowing customers to touch a tray and ensuring all flight attendants wear gloves during service.