The vaccine was met with widespread controversy and skepticism after it was rolled out before reliable data had been published. But now, scientists say its benefit has been demonstrated.

The Sputnik V vaccine is about 91% effective against the original COVID-19 strain, interim data on 20,000 people in Russia shows. There were no serious reactions linked to the vaccine, making it comparable to the Pfizer or Moderna vaccines.

“The development of the Sputnik V vaccine has been criticised for unseemly haste, corner cutting, and an absence of transparency,” write British scientists Ian Jones and Polly Roy in an accompanying commentary. “But the outcome reported here is clear and the scientific principle of vaccination is demonstrated, which means another vaccine can now join the fight to reduce the incidence of COVID-19.”

The vaccine had been approved for use on August 11 with much fanfare. It was the first approved vaccine, even as large-scale data wasn’t available until now.

The virus works in a similar way to the AstraZeneca jab, using a cold virus engineered to be harmless. The modified virus carries a small fragment of the novel coronavirus SARS-CoV-2 (but not the whole virus) to the body. The body reacts to the threat and learns to fight it off without any risk of becoming ill. The vaccine can be stored at fridge temperature and will cost around $10, making it among the cheaper vaccines (but not the cheapest).

However, unlike other vaccines, Sputnik V doesn’t use two identical doses — it uses slightly different versions. Both target the virus’ spikes, but according to developers, different formulas can boost the immune system for longer. It’s unclear if this is the case.

“The immunity required to prevent disease arose within 18 days of the first dose. That protection applied to all age groups, including those older than 60 years, and the anecdotal case histories of those vaccinated but infected suggest that the severity of disease decreases as immunity develops,” Roy and Jones’ commentary notes. “No serious adverse events considered related to the vaccine were recorded.”

It’s also unclear how well the vaccine deals with the new variants such as the ones from the UK, South Africa, or Brazil. Many researchers feel we’ll be stuck playing a game of whack-a-mole as vaccination will struggle to keep up with new strains.

At any rate, the vaccine comes at a time when we have several vaccines in the fray, but we’re still struggling on the production and distribution side. Having another effective vaccine is excellent news despite its early misgivings.

The production of Sputnik V will span multiple countries, including India, China, South Korea, and Brazil. The vaccine will also be distributed (or is already distributed) to several countries: Argentina, Venezuela, Hungary, UAE, Iran, and Palestinian territories.