Pfizer is asking Health Canada to consider boosting the number of doses it extracts from each vial of the coronavirus vaccine from five to six, a move that would allow the company to send fewer vials to Canada while still meeting its contractual obligations to send 40 million doses to Canadians.“We will fulfill our supply commitments in line with our existing agreement – which are based on delivery of doses, not vials – and in accordance with Health Canada approved labeling,” Christina Antoniou, director of corporate affairs for Pfizer Canada, confirmed in an emailed statement.The request comes amid a fervent demand for the coronavirus vaccine around the world, a hunt that has become heightened as vaccine nationalism has started to take.