What are the current official guidelines regarding COVID-19 vaccination for patients with cancer or for hematologic conditions?

There are a number of resources available to guide clinicians on these decisions. I recommend the COVID-19 Resources webpage curated by the American Society of Hematology (COI, I'm the editor of that website).

https://www.hematology.org/covid-19

This website includes guidance on immunizations in the immunosuppressed as well as for patients with other hematologic conditions, like sickle-cell disease. There are FAQ sections for each disease as well as for vaccines.

Additionally, the NCCN has recently published guidance, which is closely aligned with the ASH guidance.

ASCO has a variety of resources available on their site, including specific information about the COVID-19 vaccines in patients with cancer.

In addition, I have been working with Cancer.Net to update a blog post (daily since March 3, 2020) on what patients with cancer should know about COVID-19. The audience for this blog post are patients and the lay public. Vaccine information is highlighted in blue at the top of the post.