I learnt a long time ago not to respond to SMS messages like "How are you today?". But when I was off work for a day feeling sick and I got a message "Are you going in to work today?" I was only 80% confident it was fake.
And I responded and it was fake.
So now I don't know if "Are you going into work today?" is just a standard message that gets blasted out in the hope that it catches sick people by chance, or whether someone (an AI?) had seen my mention of testing positive for Covid here and somehow connected that to my phone number. Probably the former.