I can completely believe this. Unfortunately we can't prove any of this but personally I think my team was at least exposed to Covid in early 2020 as well. We had a guy in our (small) team room out sick from Thursday to Monday and he reported being 'floored' and coughing his lungs out. His SO got the same a few days after. Nobody else really got sick but given the close quarters and what we know about aerosol spread and incubation periods now, I think we were practically bathing in virus soup.