From a purely manufacturing perspective the idea of saline in batches is an ongoing question in my mind.. why would the pharmacy have saline vials stored w vaccines since the only use for that I know is dilute a specialized injectable like recombinant Factor VIII and those are boxed together w both vials in a box.. to clear a central line it's Heparin so it should make us ask if drug stores should be playing doctor.. head scratcher to see folks given a "wrong jab" returned for another stab at it.. thanks for the reminder saline is a player! :~)

https://web.archive.org/web/20210419092458/https://www.charlotteobserver.com/news/state/north-carolina/article250765274.html

https://web.archive.org/web/20210812094453/https://www.bbc.com/news/world-europe-58186032

https://web.archive.org/web/20211001013701/https://www.abc.net.au/news/2021-10-01/melbourne-deepdene-saline-pfizer-covid-vaccine-injection-mistake/100506516