I would not worry for one minute. I am the same as you. I never pick up the phone unless I know who it is.
My guess, going by the Indian/Pakistani accent, is fraud, or something just as credible. They probably have their phone ID set up so people answer, and you’re right....Health and Human Services would not just call you. The fact that there was silence, then you heard the phone bank and then her saying “Hello?” tells me it was a scam call. Back when I used to bother answering, just in case, as soon as I realized I was waiting for those few seconds of silence, that’s when I’d hang up.
I’d make that your rule going forward.....when you pick up and say hello and just hear the silent pause, hang up!
Agree it was scam of some sort
They want to get on tape your voice and answers to makes up a tape of you to be utilized in their attempt to reduce your money - wherever it is