Covid 19 coronavirus: Canterbury District Health Board races to use extra 1400 vaccine doses 14 Apr, 2021 04:24 AM 3 minutes to read The Pfizer-BioNTech Covid-19 vaccine must be kept at a very low temperature and expires after a few days out of the freezer. Photo / Ministry of Health The Pfizer-BioNTech Covid-19 vaccine must be kept at a very low temperature and expires after a few days out of the freezer. Photo / Ministry of Health RNZ A Christchurch GP was surprised to hear that Canterbury District Health Board (CDHB) staff were making personal Facebook posts to advise people there were spare Covid-19 vaccines up for grabs.