As far as I know, there has been no credible sources to provide proof of such. It seems to have come from sources that are of a more speculative and conspiratory in nature. I don’t want to say it is fake news, but we need concrete data. There have just been way too many theories out there lately.
The bigger question regarding the currently available covid-19 vaccines has rather to do with the fact that in various ways each brand of vaccines has employed some usage of cell lines derived from aborted material either in the stage of research and testing, and for at least one vaccine even as part of the production process. To this both the Vatican Congregation for the Doctrine of the Faith as well as the Canadian Catholic Bioethics Institute have issued statements. See:
– from CDF:
https://www.vatican.va/roman_curia/congregations/cfaith/documents/rc_con_cfaith_doc_20201221_nota-vaccini-anticovid_en.html
– from CCBI:
http://www.ccbi-utoronto.ca/2020/12/04/ccbi-resources-for-covid-19-december-4-2020/
At least by name, Pfizer vaccine was mentioned to be considered acceptable under the circumstances listed. Personally, I would counsel staying away from those vaccines that actively use aborted material in their production, if there are better vaccines available.