The Sputnik V vaccine is a two-dose adenoviral vector vaccine using two different adenoviruses for each dose, with doses administered 21 days apart. With this type of vaccine, an adenovirus is altered so that it can deliver a piece of genetic material from the virus that causes Covid-19 into the body and get cells to express the spike induce found on the virus and induce an immune response. It's an approach similar to the vaccines developed by AstraZeneca and Johnson & Johnson.
The authors say that using a different adenovirus vector for the booster vaccination may help create a more powerful immune response.
One advantage of adenoviral vaccines is that they do not need to be stored and transported in extremely cold temperatures, scientists say. Sputnik V only needs to be refrigerated and costs $10 per dose, according to Russian Direct Investment Fund, which funded vaccine production and is responsible for selling it globally.
"This is a useful addition to the published data on Covid-19 vaccine effectiveness," Dr. Julian Tang, clinical virologist at the University of Leicester.
But he highlighted that "median follow up was 48 days from the first dose, so the study cannot assess the full duration of protection."