This is a pretty reasonable interpretation. The world really is itching for and inching toward a digital currency. Even the stimulus package that was recently passed in the U.S. included some language about disbursing it through a digital wallet (to make the transactions easier to monitor). Look at the history of money from large, heavy gold bars in the Babylonian empire to coins of lesser metal (like silver, copper, bronze), then paper money, then credit cards, smart cards (with a chip), internet banking, phone banking, and now tap-and-pay is becoming the new standard. The pattern of money changing over time is undeniable and there's plenty of evidence that the changes we're seeing in the world economy are leading toward an implantable version of tap-and-pay technology.
There are so many conveniences including instantly accessible information like medical, permits of various kinds, immigration or citizenship status, and of course banking which is beneficial for the banks because they'll be able to skim a fraction from every transaction and it's good for governments because they'll not need to waste capital on printing physical money and tax collection will become much more efficient. You can't lose the implant. You can't forget it. And it can't easily be stolen. Crime which relies on cash will be dramatically reduced or eliminated altogether.
I agree with what some others have shared here that there's no need to be afraid, but there is definitely good reason to be wary. You can find the prophecy about the mark in Revelation 13:16-17 and it pretty clearly states that the purpose of the mark will be to control buying and selling. People who try to explain-away that important fact are probably doing so because they themselves have never really confronted their reliance on money. Some other people here have shared that the true purpose of the mark will be to demonstrate worship, but our reliance on buying and selling is not mutually exclusive to what it means to worship.
In other words, we show who we worship by who we give our time to. In the gospels Jesus criticized people over and over again for paying lip service to him, but not taking him seriously. He said, "why do you call me Lord, but do not obey me"? In another place he said, "The wise man is the one who hears my teachings and obeys them". In another place he quoted Isiah when he said, "This people draw near to me with their lips, but their heart is far from me".
It's easy to make a show of worship, but God looks at our actions. If we depend on the beast and his system to provide us with our daily bread, then our action demonstrates that we're not depending on God. Revelation 1:1 says the book is a revelation of Jesus Christ; he is the ultimate subject of all the prophecy. In Revelation 19:10 an angel confirms this by saying, "The spirit of prophecy is the testimony of Jesus" and in the testimony of Jesus we see a teaching which is practically the mirror of what the mark says about buying and selling. He says we cannot work for both God and money at the same time without cheating one or or the other. He says we should not let fear about food and clothing stop us from stepping out in faith and that all the world chases after these things, but that we should not be like them. He says our new, full time job is to seek God's kingdom first and God will provide the things we need as a result (Matthew 6:24-34).
In other words, the Beast will not need some special ceremony or pledge of allegiance from us to demonstrate our loyalty to him; our dependence on money as our provider is already doing that for him. If we want to put food on the table or pay the bills, we'll need to depend on him. It's a lie, of course, but an extremely effective one, which is why Paul warned that there will be great deception in the last days. Professing Christians all over the world will end up taking the mark because they've never really confronted their reliance on money (and in particular using our time to get money). They'll convince themselves that the real mark will be some kind of overt, religious display rather than simply going along with an economic system which is ever-so-slowly diversifying the method through which we preform such mundane actions as buying our daily bread. You cannot take a gold coin in to WalMart to buy food. Even though the gold has value, the system is not set up to process it properly. In the same way, a time is quickly coming when this will be true for the cash we use today.
While the medicine in a vaccine itself is not a problem, the question is whether the disease+vaccine combo will be used as a vehicle to get people over their fears of a microchip implant for the purpose of buying and selling. One way this could be achieved is to define the implant as a "certificate" to verify that one has indeed received the vaccine; (it's just that this particular certificate will have all these other benefits to it as well). If the vaccine is combined with a universal microchip containing a unique, scannable number which can be linked to a data base of information including all the stuff I reference above, in such a way that you cannot get the vaccine without also taking the chip, then it would be better to refuse.
Please note I am not saying you should not get a vaccine; I have no problem with medicine. I'm only saying that if the vaccine is combined with an implant in a way where you must take one to get the other, then you should say no.
However, as you've suggested, it is possible that the implant could be quite small, or perhaps just kept quiet in such a way that it won't be common knowledge that it's included with the vaccine. We'll need to be pretty wise as we go forward. It would be foolish to reject genuine medicine because we're too afraid to think straight, but so too would it be even more foolish to end up taking the mark of the beast because we didn't think enough.