Heterologous prime-boost vaccine:
A promising aspect of Sputnik V [the Russian-developed Covid-19 vaccine] is that it is a “heterologous prime-boost” vaccine, which means the first and second doses differ. Each dose uses a different adenovirus vector to get the coronavirus spike protein DNA into human cells. This should prevent the second shot from amplifying an immune response to the vector used in the first shot rather than to the target spike protein of the SARS-CoV-2 virus.
Heterologous prime-boost immunisation is seen as a possible way to squeeze an even bigger response from existing vaccines. [“Sputnik V: Russia’s vaccine is going global – how well does it work?” Graham Lawton, NewScientist (24 April 2021, paywall)]
