Sputnik V vaccine is a vaccine that uses what is known as ‘human adenoviral vector’ technology. Adenoviruses cause a wide range of illnesses ranging from fevers, coughs, and sore throats to pink eye, diarrhoea, and bladder infections. The adenovirus is modified and weakened so that it cannot replicate in the human body. Instead, it will act like a Trojan Horse, carrying instructions for the cells in the human body to produce the spiky outer layer (spike protein) of SARS-CoV-2, the virus that causes Covid-19.

This is expected to help the body recognise the spike protein as a foreign substance and build an immune response against it so that it can tackle the real virus when it tries to infect.

Sputnik V uses two different genetically modified adenoviruses to carry the spike protein. The vaccine containing the second adenovirus is given 21 days after the first one, and is expected to “boost” the body’s immune response and build “long-lasting immunity”.

HOW ADENOVIRAL VECTOR-BASED VACCINES WORK

“Vectors” are vehicles, which can induce a genetic material from another virus into a cell. The gene from adenovirus, which causes the infection, is removed while a gene with the code of a protein from another virus spike is inserted. This inserted element is safe for the body but still helps the immune system to react and produce antibodies, which protect us from the infection.

The technological platform of adenovirus-based vectors makes it easier and faster to create new vaccines through modifying the initial carrier vector with genetic material from new emerging viruses that helps to create new vaccines in relatively short time. Such vaccines provoke a strong response from a human immune system.

Human adenoviruses are considered as some of the easiest to engineer in this way and therefore they have become very popular as vectors.