I think it’s a safe bet that vaccines will prevent serious illness and death. By blocking travel from Europe a few weeks after a long ban, the Biden administration will damage relations with the EU and airlines will once again take a hit. I don’t believe he sees that the benefits here outweigh the risks.
Besides, some European countries report no cases (yet), such as Sweden, Finland and countries outside the EU (Hong-Kong, Israel and Australia) have several cases. They would need to be banned too then. On top of that, two were found in Canada yesterday.