A hacker group known as “KelvinSecurity” has leaked hundreds of documents that allegedly contain information on the development of Russian Sputnik V COVID-19 vaccine, including data on deaths of participants in the vaccine's clinical trials.

The group’s representative told the news site Cybernews that the goal of the leak was to show that the vaccine “is not efficient and it was only Russian government propaganda.”

The Russian authorities touted the Sputnik vaccine (Gam-COVID-Vac) developed by the Gamaleya Research Institute of Epidemiology and Microbiology as “the world's first registered COVID-19 vaccine" in 2020. Sputnik was authorised in Russia before any clinical studies were published, and subsequent trial results proved controversial, casting doubt on the efficacy of the vaccine.

According to KelvinSecurity, the data came from “the review of the mailboxes of the developer company,” indicating a possible breach at the Gamaleya Research Institute.

Clinical trials where patients had allegedly died included countries like Ghana and Egypt, KelvinSecurity said. The leaked dataset also includes classified documents containing information on the vaccine's development phases, funding, and quality, as well as some specific cases pertaining to clinical trials.

In one instance a “subject” experienced a “spontaneous abortion” one month after getting vaccinated on 17 February 2022, although it’s unclear whether the vaccination and pregnancy loss were related.

Some documents reviewed by Cybernews contain invoices and refer to the costs of research papers, with one priced at seven million roubles (~$93,000). There is also information on different laboratories that produced the vaccine and their yield levels.

Besides internal emails, the leak is said to contain external communication. For example, an email from a Swiss company says it was “enthused by the research path chosen by your institute,” asking if it could import Sputnik V vaccines to Switzerland. Most of Europe, including Switzerland, has never authorized the vaccine, Cybernews notes.