Five or six doses? Controversy over Pfizer Covid-19 vaccine vials

The US pharmaceutical giant Pfizer, which is manufacturing the Covid-19 vaccine developed by Germany's BioNTech, now considers each vial contains six doses compared to five previously.

The difficulty in obtaining that sixth dose in practice means many countries are at loggerheads with Pfizer and facing a drop in supply.
 

Until recently, each vial of the BioNTech-Pfizer vaccine was considered to officially contain five doses.
 

After being thawed, the contents of each vial are diluted with 1.8 ml of saline solution, creating a total of 2.25 ml of injectable solution. With each dose 0.3 ml, in theory there are just over