Chambers 1908 has an adj sense: "pertaining to or derived from cows; of or relating to vaccinia or vaccination". Equinox ◑ 21:45, 12 May 2019 (UTC)
The origin of vaccine (en) from vacca (lat) sounds very strange to me. Since the medical discovary way about the virus ('variolae vaccinae) and not about the cow. There is also less transformation from vaccinae (lat) to vaccine (en) compared to the postulated origin from vacca/vaccinus (lat). See also this explanation from 1798, which sounds more resonable than the non-existing explanation saying vaccine (en) is originated from the Latin word for cow. "In 1798, Jenner published a lengthy report called ‘An Inquiry into the Causes and Effects of the Variolae Vaccinae’. Jenner translated the term ‘vaccinae’ from the Latin for ‘cow pustules’. Which, in turn, came from the Latin words ‘vacca’ (cow) and ‘vaccinus’ (from cows). "
https://quicksilvertranslate.com/12964/the-etymology-of-the-word-vaccine https://www.bartleby.com/38/4/1.html