We are in the post-pandemic era of HCoV-OC43 despite not having a vaccine. It is very similar to SARS-CoV-2 and there is circumstantial evidence that it caused the pandemic of 1889. The only reason it kills few people today is that most of us are infected as youths and build up immunity.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7252012/