Truthfully, I really doubt that the mark will be a vaccination. Reason being is that, if we stay with the clues in Revelation, then the mark will be localized in the hand or the forehead and will be used to allow people to buy and sell. Putting that into perspective for today, buying and selling would be electronic crediting and debiting of ones bank account. Here's the scripture:
"And the second beast required all people small and great, rich and poor, free and slave, to receive a mark on their right hand or on their forehead, so that no one could buy or sell unless he had the mark—the name of the beast or the number of its name. (Rev.13:16-17)
Regarding this, Sweden and her sister countries are way ahead of the US in that, they have been pretty much a cashless society using only bank cards for making purchases. Since 2015, their citizens have been receiving RFID chip implants underneath the skin between the index finger and thumb. Now, more more people are being chipped and instead of using bank cards, they are now having their hands scanned to pay things such their train tickets and food purchases.
A vaccination is not stationary, but travels throughout the body and therefore it does not fit the criteria of the mark which will be located on either the hand or forehead. It is this mark, which will be some type of miniature device which will allow a person to perform crediting and debiting to their bank account. I believe that this current RFID technology will evolve into something smaller and more applicable in preparation for the coming beast.
Another thing is that, this mark will not be something that is forced upon anyone against their will, but must be receive by personal choice of the individual. Otherwise, God could not hold them accountable for receiving the mark. The only way that this can work, is by making all other methods of buying and selling obsolete, so that there is only one valid way of access ones money, ergo the false prophet forces all people. I'd be kind of like living out in the boonies where there is only one cable company. Either you buy their cable or you won't have any. It will be the same with the mark, anyone who does not receive the mark, will have no way to access their money. Check out the following secular video the RFID chipping in Sweden:
I Put A Payment Chip In My Hand To Replace My Wallet - Bing video
Why human microchipping is so popular in Sweden | ITV News - Bing video