Fact check: How effective is the Sputnik V coronavirus vaccine?

Russia's COVID-19 vaccine, Sputnik V, has been approved for use in dozens of countries, and it's also under review by the European Medicines Agency. But the vaccine remains controversial.

President Vladimir Putin has touted Sputnik V as "the best vaccine in the world," and the Russian media have regularly touted the vaccine's record exports abroad.

However, is it actually a safe and effective inoculation against COVID-19? DW tries to separate the facts from the propaganda.

What is Sputnik V?

Developed by the state-run Gamaleya Research Institute of Epidemiology and Microbiology in Moscow and financed by the Russian Direct Investment Fund (RDIF), Gam-COVID-Vac is a viral vector vaccine, similar to those developed by AstraZeneca and Johnson & Johnson (J&J). Vector vaccines are easier to manage than mRNA vaccines, which need to be stored at very low temperatures.

In a vector vaccine, harmless viruses, such as inactive cold viruses, deliver the genetic code for spike proteins — which the SARS-CoV-2 pathogen uses to attach itself to human cells — into the body. The body of a vaccinated person will recognize them as alien substances and react by creating antibodies and specific T-cells, which are both important for immunity.

What's unusual about Sputnik V, however, is that two different types of cold virus, or adenovirus, are used for the first and second shots — rAd26 (which J&J also uses) and rAd5, respectively. This combination is supposed to prevent the second shot from neutralizing the immunization effect from the first and preventing the desired booster effect.

How effective is Sputnik V?

In principle, it's possible to use two different vectors because this promises a higher vaccine efficacy. The efficacy of other vector vaccines such as AstraZeneca (76%) and J&J