Russian President Vladimir Putin announced on Tuesday that he will approve the first covid-19 vaccine, Sputnik V, after less than two months of testing on humans. This has raised alarm among health experts worldwide, as, without complete clinical trial data, it is “difficult to trust the vaccine”.

With the intention of being the first in the global race to develop a vaccine against covid-19, Russia has yet to carry out large-scale trials in order to have sufficient scientific evidence to prove whether it is effective – something that immunologists and specialists in infectious diseases they say it could be a “reckless” step.

“Russia is essentially carrying out a large population-based experiment,” Ayfer Ali, a specialist in drug research at Warwick Business School in the United Kingdom, told Reuters.

According to Ayfer Ali, such a rapid approval could mean that the potential adverse effects of the vaccine are not detected, and although they may be rare, they can be serious, he warned.

Sputnik V has not yet gone through the third phase of clinical trials, which would show, for example, whether the vaccine has adverse effects and whether it can, in fact, be administered on a large scale.

However, Vladimir Putin said the vaccine, developed by the Gamaleya Institute in Moscow, was safe and had even been administered to one of his daughters.

“I know it is very effective, it creates strong immunity and, I repeat, passed all the necessary tests,” he said on state television.

Francois Balloux, an expert at University College London’s Genetics Institute, says it’s “an unwise and foolish decision”.

“Mass vaccination with a poorly tested vaccine is unethical,” he said. “Any problem with the Russian vaccination campaign would be disastrous, due to the negative health effects and because it would further delay the acceptance of vaccines in the population.”

Health experts say that the lack of published data on the Russian vaccine – including how it is done, details on safety, immune response, and whether it can effectively prevent infection – leaves many doubts to scientists, health authorities and the population.