No, but it may as well be considered sterile for normal purposes. Boiling doesn’t actually kill everything - endospores and also fungal spores are ridiculously hardy, and you’d need to autoclave (steam at high pressure) in order to really kill everything. And microbes are everywhere, so the tea is going to get colonized again really quickly unless you pay special attention to making sure that that doesn’t happen. Don’t attempt to can or store the tea, if that’s what you’re trying to do. Also, if you’re attempting to use unsanitary water to make tea, be aware that some bacteria and fungi make toxins that can’t be destroyed by boiling, so even if you manage to kill off the microbes, you can still get sick.