Are they RNA based?
Do they alter your DNA at all?
I don't think any will be the actual mark of the beast, as the Bible says you will know that you are taking it and will have to do so willingly, so more than likely will know that you are worshipping the image of the beast, but they could be doing a trial run for another event, like another deadly disease that is much worse than Covid that kills many more people. And so many will take the mark as they will be scared of dying and will do so willingly even though that means worshipping the image of the beast.
Some say that the mark will alter your DNA. There is plenty speculation that the mark will include a vaccine and it could be (well, no it would be) a trojan horse as the Bible says that boils form on the skin of those who take the mark and worship the beast. Now the boils could be a result of the mark itself, but we do know that it signifies those who took the mark and those who worship the beast's image.
REVELATION 16:2
And the first went and poured out his vial upon the earth; and there fell a noisome and grievous sore upon the men who had the mark of the beast and upon them that worshipped his image.