Perhaps it is a scam?

I'm sure people are planning one. That doesn't mean they will be successful. Most of the people with enough money to do this are alert for scams (though they might decide it is 80% chance of scam and decide to risk it anyway), so they will be looking to see if they will get the vaccine in the end, and if they don't think you will deliver they won't go. I would expect anyone who gets a "black market" vaccine gets one of the not approved (yet) vaccines. That supply is sitting around and probably not tracked as much. Break into a warehouse (often with insider help, possibly at high levels such that most people in the company help you because your alibi checks out), get a supply, then send it to your black market buddies. Pfizer has a legal market now and will do everything to ship to that market. Moderna is close enough that they won't risk it. The Oxford vaccine has a lot of companies who can make it and an uncertain future (60% effective when there is a 95%?) so it is the most likely candidate, for this. Russia also is making a vaccine that they might be willing to sell like this. China might as well, but I find it unlikely as they have other markets. Of course this whole paragraph is pure speculation: anything is possible.