Sputnik V vaccine developed by Russia is a two-dose vaccine. The unique feature of the vaccine is that the first and second dose are different from each other. In Sputnik Light a single dose is sufficient.
Sputnik V
Sputnik V is also known as Gam-COVID-Vac. It uses heterogenous recombinant adenovirus approach. Meaning, Sputnik V is a two-vector vaccine. It uses Adeno Virus 26 in the first dose and Adeno Virus 5 in the second dose. These Adeno Viruses are the carriers.
Conjugate Vaccine
A Conjugate Vaccine is a vaccine that uses a weak antigen with a strong antigen as a carrier. It is informally called a carrier vaccine. Sputnik V is a Conjugate Vaccine.
Why a double dose earlier?
Adenoviruses are common. They are ubiquitous (commonly found everywhere) in the environment that is contaminated by human faeces or sewage. They cause common cold and fever. This means that Adeno virus is commonly found in the humans. This is one of the main reasons why adeno virus based COVID-19 vaccines are single dose vaccines. However, Sputnik V was a double dose vaccine. This was done to booster the immune response compared to use the same vector twice.
Why a single dose now?
Sputnik V vaccine was sold at 10 USD in other markets. In India it is facing difficulties to compete with AstraZeneca Vaccine, also called COVISHIELD, which is sold at 2 USD per dose. The price of COVISHIELD is low in India as it is manufactured locally by the Serum Institute of India. On the other hand, Sputnik V is imported. It is marketed by Dr Reddy’s Laboratories. Now, to compete with COVISHILED and capture the market, the price has to be reduced, which is, highly impossible as the vaccine is being imported. Thus, a single dose vaccine is being launched. India is planning to launch this single dose vaccine.