CDC recently announced that the rare side effects that resulted in 57 cases and 9 deaths due to thrombosis with thrombocytopenia syndrome and 278 preliminary reports of Guillain-Barré Syndrome from 16.9 million doses of the Johnson and Johnson/Janssen COVID-19 vaccine have encouraged the Advisory Committee on Immunization Practices to update the recommendations on vaccine use.
Clinical preferences now lean towards mRNA vaccines such as Pfizer/BioNTech and Moderna over J&J/Janssen since vaccine stocks are plentiful. However, they emphasize that a J&J vaccine is still better than no vaccine at all.
Read the CDC media statement here, and the adverse events report here.