Japan is scrambling to secure special syringes to maximise the number of Covid-19 vaccine shots used from each vial, but manufacturers are struggling to ramp up production quickly, raising fears that millions of doses could go waste.Japan, with a population of 126 million, last month signed a contract with Pfizer Inc to procure 144 million doses of its vaccine, or enough for 72 million people, with the vaccination campaign set to start on Wednesday.Also Read | Inside the five-year battle food companies have fought to resist stricter labelling normsOne vial is meant for six shots, Pfizer says, but it takes special syringes that retain a low volume of solution after an injection to extract six doses, while only five shots can be taken with.