Most of the candidates currently on the market, or in development, are designed to be administered over two doses. These doses are generally spaced apart by around 2-4 weeks, with efficacy increasing after the second dose.
Some vaccines can be given in just a single dose. The upcoming Johnson & Johnson vaccine and CanSino’s vaccine are two high-profile examples. A single dose vaccination presents several advantages. Not only can the vaccines be administered more quickly, but a sufficient number of jabs can also be purchased for less money – as only half as many doses are needed.